WO2014122071A1

WO2014122071A1 - Increasing the lifetime of an organic phosphor by using off-maximum excitation

Info

Publication number: WO2014122071A1
Application number: PCT/EP2014/051900
Authority: WO
Inventors: Rifat Ata Mustafa Hikmet; Dirk VELDMAN; Ties Van Bommel; Johan Lub
Original assignee: Koninklijke Philips NV
Current assignee: Koninklijke Philips NV
Priority date: 2013-02-11
Filing date: 2014-01-31
Publication date: 2014-08-14
Anticipated expiration: 2015-08-11

Abstract

The invention provides a lighting device comprising (i) a source of light for generating light source light having a spectral distribution with a maximum intensity at a first wavelength (λ1) within the visible wavelength range, (ii) a light converter comprising an organic luminescent material, wherein the light converter is transmissive for at least part of the light source light, wherein the organic luminescent material is configured to provide upon excitation with the light source light luminescent material light having a wavelength within the visible wavelength range, wherein the organic luminescent material has an excitation spectrum having a maximum excitation intensity at a second wavelength (λ2), and wherein λ1≠λ2.

Description

Increasing the lifetime of an organic phosphor by using off-maximum excitation

FIELD OF THE INVENTION

The invention relates to a lighting device comprising a source of light and a luminescent material.

BACKGROUND OF THE INVENTION

The use of organic luminescent materials for lighting applications is known in the art. WO2012046175, for instance describes a light-emitting arrangement comprising a light source adapted to emit light of a first wavelength, a wavelength converting member comprising an organic wavelength converting material adapted to receive light of said first wavelength and to convert at least part of the received light to light of a second wavelength, said wavelength converting member and said light source being mutually spaced apart; and a sealing structure at least partially surrounding said wavelength converting member to fonn a sealed cavity containing at least said wavelength converting member, the gas pressure within said sealed cavity being 1 * 10 ⁵ bar ( 1 Pa) or less. At such pressure, the organic phosphor has been found to have particularly good stability, thus resulting in a longer life time of the phosphor. The organic luminescent material or organic phosphor may for instance include a perylene derivative.

WO2012/042434 describes a light-emitting arrangement with organic phosphor, especially a light-emitting arrangement, comprising: a light source adapted to emit light of a first wavelength; a wavelength converting member comprising an organic wavelength converting compound adapted to receive light of said first wavelength and to convert at least part of the received light to light of a second wavelength, said wavelength converting member and said light source being mutually spaced apart; and a sealing structure at least partially surrounding said wavelength converting member to form a sealed cavity containing at least said wavelength converting member, said sealed cavity containing an inert gas and oxygen gas, the concentration of oxygen gas being in the range of from 0.05 to 3 % based on the total volume within said sealed cavity.

WO2012/ 140542 describes a luminescent converter, a phosphor enhanced light source or a luminaire having a CRI larger than 80, especially a luminescent converter a phosphor-enhanced light source and a luminaire are provided. The luminescent converter comprises a first organic luminescent material, a second organic luminescent material and a third inorganic luminescent material. The first organic luminescent material, the second organic luminescent material and the inorganic luminescent material absorb a portion of light emitted by the light source and/or absorbs a portion of light emitted by at least one of the other luminescent materials. The first organic luminescent material converts at least a part of the absorbed light into light of a first color distribution. The second organic luminescent material converts at least a part of the absorbed light into light of a second color distribution. The inorganic luminescent material converts at least a part of the absorbed light into a third color distribution to compensate self-absorption of light by at least one of the first organic luminescent material and the second organic luminescent material

EP0227980 describes fluorescent aroxysubstituted 3,4,9.10- perylenetetracarboxylic acid-dumides and their use for the concentration of lights in small areas.

SUMMARY OF THE INVENTION

Organic phosphors (herein also indicated as organic luminescent materials) are currently being considered for (remote) phosphor applications where blue light emitting diodes arc used for pumping green to red emitting phosphor in order to obtain white light. Organic phosphors have a large number of advantages as compared with inorganic phosphors. The position and the band width of the luminescence spectrum can be designed with ease to be anywhere in the visible range to obtain high efficacy.

One of the drawbacks of the organic phosphor may be their lifetime during irradiation. During irradiation by the pump wavelength the molecules bleach. It is usually assumed that irradiation with shorter wavelengths has a negative influence on the lifetime of the molecules as compared to irradiation at longer wavelengths.

Hence, it is an aspect of the invention to provide an alternative lighting device which makes use of an organic luminescent material, (but) which preferably further at least partly obviates the above-described drawback.

It was surprisingly found that the bleaching (of the organic luminescent material) depends on the absorbed light per molecule. In other words when the molecules are irradiated at a wavelength where the extinction coefficient is lower, the lifetime of the molecule increases. For example it was found that a molecule showing a lower extinction coefficient in blue part of the spectram than in yellow, when irradiated with a blue source of light showed a factor of 7 longer lifetime than when irradiated by a yellow source of light.

Hence, it is suggested using molecules and configurations for decreasing the absorbed light per molecule. For example, this can be done by designing molecules with a low extinction coefficient at the wavelength of absorption (i.e. wavelength of (main) excitation). One can (thus) also use wavelengths to excite the molecule where the extinction coefficient of the molecule is lower. In the case of multi phosphor systems, strategies for reducing phosphor-phosphor interactions for increased lifetime are suggested.

Hence, in an aspect the invention provides a lighting device comprising (i) a source of light for generating light source light having a spectral distribution with a maximum intensity at a first wavelength (λΐ) within the visible wavelength range, (ii) a light converter comprising an organic luminescent material, wherein the light converter is transmissivc for at least part of the light source light, wherein the organic luminescent material is configured to provide upon excitation with the light source light luminescent material light having a wavelength within the visible wavelength range, wherein the organic luminescent material has an excitation spectrum having a maximum excitation intensity at a second wavelength (λ2), and wherein λϊ≠ λ2.

With such lighting device, lifetime of the organic luminescent material may substantially be increased. Hence, especially the invention uses the application of a sub- optimal excitation to increase lifetime of an organic luminescent material. Thereby, also the lifetime of the lighting device is increased.

The phrase "wherein the organic luminescent material is configured to provide upon excitation with the light source light luminescent material light having a wavelength within the visible wavelength range" indicates that the organic luminescent material is excitable by the light source light of the source of light. Hence, though not having maximum excitation intensity at λΐ , the organic luminescent material will especially have at λΐ a nonzero excitation intensity (i.e. ε will in general be non-zero). However, the excitation intensity is not at maximum at λΐ but lower than the maximum (excitation intensity) at X2. Hence, the organic luminescent material is configured to provide luminescent material light having a wavelength within the visible wavelength range upon excitation with the light source light.

Preferably, the source of light is a source of light that during operation emits (light source light) at least light at a wavelength selected from the range of 200-600 ran, especially a source of light that during operation emits at least light at wavelength selected from the range of 400-600 ran, such as in the range of 400-500 nm, even more especially in the range of 440-490 nm. Hence, for instance the source of light may generate light source light with a spectral distribution with a maximum in the range of 440-490 rim. This does however not exclude the presence of light source light in other wavelength ranges. The light source light especially has somewhere in the spectral distribution of the light a maximum at a specific wavelength though other wavelengths are not excluded. This wavelength is indicated as λΐ ; λΐ is especially in the blue wavelength range. In a specific embodiment, the source of light comprises a solid state light source, such as a light emitting diode (LED) or a laser, for instance a blue light emitting diode (LED).

The term "source of light" may especially relate to an electronic source, such as a LED light source. In such instance, also the term "light source" may be applied. In specific embodiments, however, the source of light may also be a luminescent material (that is excited by another source of light, especially e.g. a LED light source). In such instance, there is a cascade, wherein the light source excited a luminescent material, wherein the luminescence of the luminescent material is at least partly be used by another luminescent material as excitation light. Note however that the present invention especially uses the principle of direct excitation for organic luminescent materials, even when there is a plurality of organic luminescent materials available. However, an organic luminescent material may optionally be applied herein as source of light for an inorganic luminescent material. Hence, the organic luminescent material is essentially excited by the (light source light of the) source of light only. In other words, the lighting device is especially configured to allow the organic luminescent material being essentially excited by the (light source light of the) source of light only. Hence, in embodiments the organic luminescent material may derive especially at least 90% of the excitation (energy) from the (light source light of the) source of light only, especially an LED light source, and not by other light sources. In an embodiment, a combination of different types of sources of light are applied.

This light source light may partially be used by the organic luminescent material (see further also below). Hence, in a specific embodiment, the source of light is configured to generate blue light. In a specific embodiment, the source of light comprises a solid state LED light source (such as a LED or laser diode). The term "source of light" may also relate to a plurality of sources of light, such as 2-20 (solid state) LED source of lights. Hence, the term LED may also refer to a plurality of LEDs.

The lighting device may especially be configured to generate white light. This may in an embodiment be created by the combination of the source of light emission (i.e. light source light of the source of light), which especially includes blue light, and the emission of the organic luminescent material, which may e.g. include one or more of green, yellow, orange and red light. Optionally, also other luminescent materials may be used in the lighting device to provide (white) (lighting device) light (see also below). The term white light herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K, and for backlighting purposes especially in the range of about 7000 K and 20000 K, and especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

The terms "violet light" or "violet emission" especially relates to light having a wavelength in the range of about 380-440 run. The terms "blue light" or "blue emission" especially relates to light having a wavelength in the range of about 440-490 ran (including some violet and cyan hues). The terms "green light" or "green emission" especially relate to light having a wavelength in the range of about 490-560 nm. The terms "yellow light" or "yellow emission" especially relate to light having a wavelength in the range of about 540- 570 nm. The terms "orange light" or "orange emission" especially relate to light having a wavelength in the range of about 570-600. The terms "red light" or "red emission" especially relate to light having a wavelength in the range of about 600-750 nm. The term "pink light" or "pink emission" refers to light having a blue and a red component. The terms "visible", "visible light" or "visible emission" refer to light having a wavelength in the range of about 380-750 nm.

The light converter comprises a material that is able to convert the light source light and/or optionally light of another source (such as another luminescent material) into emission light of the luminescent material. Hence, the light converter may also be indicated as wavelength converter. The light converter is especially a transmissive material that includes an organic luminescent material. This organic luminescent material may be molecularly dispersed therein. Hence, the material of the light converter may also be indicated as host material. This host material hosts the organic luminescent material.

Especially, the light converter comprises a polymeric material (or polymeric host). In an embodiment, the light converter comprises one or more materials selected from the group consisting of PE (polyethylene), PP (polypropylene), PEN (polyethylene napthalate), PC (polycarbonate), polymethylacry!ate (PMA), polymethylmethacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), silicone, polyvinylchloride (PVC), polyethylenctcrcphthalatc (PET), (PETG) (glycol modified polyethyleneterephthalate), PDMS (polydimeihylsiloxane), and COC (cyclo olefin copolymer). Such materials are herein also indicated as host material and may also be indicated as matrix material. The light converter comprises thus in embodiments a host (or matrix) (materia!) comprising an organic luminescent material. In a specific embodiment, the light converter comprises polyethyleneterephthalate (PET) as material. In a specific embodiment, the light converter is transparent. In a specific embodiment, the light converter highly transmissive and shows a low degree of back scattering thus transmits light to a large extent. However, the light converter may optionally also be translucent, such as due to surface structure and /or volume scattering. Especially however, in an embodiment the light converter is configured to allow transmission of at least part of the light source light, especially blue light (from a source of light generating (at least) blue light).

Especially, the material has a light transmission, even more especially outside the range where the organic luminescent molecule absorbs, in the range of 50-100 %, especially in the range of 50-90%, such as in the range of 70-90%. Hence, back scattering is especially in the range 10-50% and most preferentially in the range 10-30%. The

transmission or light permeability can be determined by providing light at a specific wavelength with a first intensity to the material and relating the intensity of the light at that wavelength measured after transmission through the material, to the first intensity of the light provided at that specific wavelength to the material (see also E-208 and E-406 of the CRC Handbook of Chemistry and Physics, 69th edition, 1088-1989).

Hence the phrase "transmissive for at least part of the light source light" especially indicates that when providing light source light to one side (face) of the light converter part of the light will be transmitted through the light converter and can be found at another side (face) of the light converter (downstream). Further, part of the light may be absorbed by the light converter. When absorption occurs, the extent in which is absorbed may- depend on the wavelength of the light offered to the light converter. Hence, the spectral distribution of the light of the light source light that is transmitted through the light converter may in embodiments differ from the spectral distribution of the light source light. Hence, in an embodiment the light converter is configured in the device in a transmissive configuration, i.e. with the source of light at one side of the light converter and lighting device light escaping at the other side of the light converter. In an alternative configuration, see also below, the light converter is configured in the device in a reflective configuration. As indicated above, the light converter is especially transmissivc. Hence, the invention is especially directed to those type of devices wherein a light source generates light, with the light converter arranged downstream of the light source, and with light escaping from the light converter at an other side of the light converter, i.e. especially light travels through the entire light converter. In general, the light converter will be a layer or a plate, with a light source at one side, and lighting device light escaping downstream from the light converter. However, optionally the light converter may also be configured in reflective mode. Hence, in a further aspect the invention also provides a lighting device comprising (i) a source of light for generating light source light having a spectral distribution with a maximum intensity at a first wavelength (λΐ) within the visible wavelength range, (ii) a light converter comprising an organic luminescent material, wherein the organic luminescent material is configured to provide upon excitation with the light source light luminescent material light having a wavelength within the visible wavelength range, wherein the organic luminescent material has an excitation spectrum having a maximum excitation intensity at a second wavelength ( 2), and wherein λΙ≠ 12, and wherein especially the light converter is arranged in a reflective configuration.

The light converter may especially be radiationally coupled to the source of light, i.e. they are functionally coupled. The term "radiationally coupled" especially means that the source of light and the luminescent material (i.e. the organic luminescent material comprised by the light converter) are associated with each other so that at least part of the radiation emitted by the source of light is received by the luminescent material (and at least partly converted into luminescence).

In an embodiment, the light converter is arranged remote from the source of light. Especially, the organic luminescent materials are arranged remote from the LED die (i.e. not in physical contact with the LED). The shortest distance between the source of light (exit surface), such as a LED (die), and one or more of the luminescent materials, preferably all luminescent materials, may be larger than 0 mm, especially equal to or larger than 0.1 mm, such as 0.2 or more, and in some embodiments even equal to or larger than 10 mm, such as 10-100 mm, A remote application may further increase lifetime. However, the present invention also includes applications wherein the light converter is in physical contact with the LED die (or other light source (surface)). At a non-zero distance, but remote from the light source may also be indicated as "in the vicinity".

The term light converter may refer to a system that is configured to convert light from a first wavelength into light of a second wavelength. Especially, UV and or blue light (excitation wavelength) may be (at least partially) converted into visible light (of higher wavelength than the excitation wavelength).

The light converter may be in the form of for instance particles, flakes, a film, a plate, etc. In a specific embodiment, the term light converter may include a self supporting layer.

Hence, in an embodiment, the light converter is selected from the group consisting of a coating, a self supporting layer, and a plate; which light converter is thus especially solid at room temperature, especially even up to 100 °C, especially even up to 150 °C, especially even up to 200°C). The light converter may be flexible or may be rigid.

Further, the light converter may be flat or curved (in one or two dimensions). Further, optionally the light converter may comprise outcoupling structures at at least part of the external surface of the light converter.

The light converter may comprise one or more parts, like layers on top of each other. Such parts may comprise different luminescent materials or luminescent materials in different concentration. However, at least part of the light converter comprises the (red) organic luminescent material.

The matrix may especially comprise a matrix material and the above indicated materials such as the organic luminescent material, and optionally inorganic luminescent material, etc. The organic luminescent material(s) and optionally other luminescent materials may in an embodiment especially be evenly distributed throughout the matrix. However, the light converter may also comprise two or more segments, wherein two or more segments have different compositions at least with respect to the luminescent material(s), e.g. with respect to type and/or concentration of the luminescent materiai(s).

As indicated above, the light converter comprises an organic luminescent material. The organic luminescent material can be any organic luminescent material, but is especially selected from the group consisting of organic luminescent materials that have emission in the visible. However in specific embodiments (organic) luminescent material may have emission in near red and infrared. Thus, especially the organic luminescent materials is configured to provide luminescent material light (upon excitation by (light source light of) a source of light, especially the source of light), having a wavelength within the visible wavelength range. Again, this does not exclude the existence of emission in other wavelength ranges, though preferably substantially all the emission (energy) is within the visible wavelength range. The organic luminescent material has an excitation spectram. This excitation may comprise one or more maxima. The highest maximum is at a second excitation wavelength λ2. As indicated above, λ\≠ λ2, leading to an excitation of the organic luminescent material that is shifted relative to the maximum excitation wavelength. This is in contrast to general considerations, wherein the organic luminescent material and source of light should be chosen to obtain maximum efficiency. The choice of the present invention may include that relatively more organic luminescent material is needed. However, the lifetime of the device increases. Examples of specific organic luminescent materials can be found below. Note that the term "organic luminescent material" may in embodiments also relate to a plurality of different organic luminescent materials (see also below).

in a specific embodiment, the spectral distribution of the light source light of the source of light and the excitation spectrum of the organic luminescent material have a (normalized) spectral overlap SO in the range of 0<SO<0.4, such as 0.01 <SO<0.4. wherein the normalized spectral overlap is defined as:

wherein Ι(λ) is the intensity of the source of light as a function of wave length, wherein ε(λ) is the extinction coefficient as a function of wavelength based on the excitation spectrum, wherein e_max is the maximum extinction coefficient in the wavelength range of 350-900 nm (i.e. λχ- Xy) , based on the excitation spectrum, and wherein λ_χ and X_y define the wavelength range of 350-900 nm. For instance, the normalized spectral overlap may be 0.35 or less, such as in the range of 0.1-0.3. Especially, the above equation is applied for the wavelength range(s) of 400-900 nm (i.e. λ_χ=400 and λ_γ=900 nm).

a specific embodiment, the organic luminescent material is selected from the group consisting of:

10

10

Therefore, especially the organic luminescent material is especially a material according to formula (I):

in which:

Gi and G_f, independently comprise a group selected from a linear alkyl, a branched alkyl, an oxygen-containing alkyl, a cycloaikyl, a naphtyl, and Y;

- wherein each of A, B, C, J and Q independently comprise a group selected from hydrogen, fluorine, chlorine, isopropyl, t-butyl, methoxy, an alkyl with up to 16 carbon atoms, and an oxygen containing alkyl with up to 16 carbon atoms;

G₂, G3, G4 and G5 independently comprise a group selected from hydrogen, fluorine, chorine, isopropyl, t-butyl, methoxy, alkyl with up to 16 carbon atoms, and oxygen- containing alkyl with up to 16 carbon atoms, and X;

- wherein each of D, E, I, L and M independently comprise a group selected from hydrogen, fluorine, chlorine, isopropyl, t-butyl, methoxy, alkyl with up to 16 carbon atoms, and an oxygen-containing alkyl with up to 16 carbon atoms;

and in which (in a specific embodiment)

at least two selected from G2, G3, G4, and G5 at least comprise X, wherein (in a specific embodiment) independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine, especially fluorine.

Especially, at least two of said at least two selected from G2, G3, G4, and G5 comprise two or more groups selected from fluorine and chlorine, especially fluorine.

However, chlorine groups appear to provide good results as well. Desired optical properties may especially be obtained when all G2-G5 at least comprise X (and at least two, especially all four, comprise a fluorine subsiituent). Hence, in an embodiment G2-G5 are each independently X.

The linear alkyl, branched alkyl, oxygen containing alkyl (see also below), cycloalky!, and the naphtyl, as defined above for especially Gl and G6, may especially comprise up to 44 carbon atoms. The alkyl (or naphty!) may also be substituted with fluorine.

In an embodiment, Gl and G6 are each independently C_nH?_n+i._mF_m with n < 44, and m < 2n+l . Other substitoents are not excluded. Especially, the alkyl comprises up to 20, such as up to 10, like up to 8 carbon atoms.

The oxygen containing alkyl, with especially up to 44 carbon atoms, as defined above for especially Gi and G6, may in an embodiment especially relate to

C_tftn+iOn,, with n being an integer from 1 to 44 and m < n/2. The oxygen containing alkyl, with especially up to 44 carbon atoms, may also be substituted with fluorine. Other

substituents are not excluded. The oxygen containing alkyl may be linear, branched, or cyclic, or may be a combination of two or more thereof. The oxygen containing alkyl especially comprises an alcohol or an ether, such as an oh go ethylene oxide. Especially, n is up to 20, such as up to 10, like up to 8.

Gl and G6 may be the same or may be different (see also below). The alkyl with up to 16 carbon atoms, as defined above for A, B, C, J, Q, G2, G3, G4 and G5, D, E, I, L and M, especially relate to CJHb_n+i , with n being an integer from 1 to 16. The alkyl may be linear, branched, or cyclic, or may be a combination of two or more thereof. The alkyl with up to 16 carbon atoms may also be substituted with fluorine (see below). Other substituents are not excluded. Especially, the alkyl comprises up to 10, such as up to 8 carbon atoms.

The oxygen containing alkyl with up to 16 carbon atoms, as defined above for A, B, C, J, Q, G2, G3, G4 and G5, D, E. I, L and M, especially relates to C_nH_2n+iO_m, with n being an integer from 1 to 16 and with m < n/2. The alkyl may be linear, branched, or cyclic, or may be a combination of two or more thereof. The oxygen containing alkyl with up to 16 carbon atoms may also be substituted with fluorine (see below). Other substituents are not excluded. Especially, n is up to 10, such as up to 8.

Hence, in an embodiment, the alkyl with up to 16 carbon atoms may at least partially be substituted with fluorine, and may in an embodiment especially relate to C_nH_2n+i- _mF_m with n being an integer from 1 to 16 and with m < 2n+l . The fluorine substituted alkyl may be linear, branched, or cyclic, or may be a combination of two or more thereof. Other substituents are not excluded. Especially, n is up to 10, such as up to 8. A, B, C, J, Q may independently be chosen. G2, G3, G4 and G5 may independently be chosen. D, E, I, L and M may independently be chosen.

In a further aspect, the invention also provides a light converter per se, especially a light converter comprising a matrix containing an inorganic luminescent material and an organic luminescent material as defined by formula (I), with

Gi,G2,G3,G4,G5,G6,X,Y,A,B,C,D,E,I,J,M,L as defined above (and farther below).

In yet a further aspect, the invention also provides such organic luminescent material per se, especially an organic luminescent material as defined by formula (I), with G1,G2,G3,G4,G5,G6,X₃Y,A,B₅C,D,E,1_!J,M,L as defined above (and further below).

Advantageously, such organic luminescent material may have a red luminescence (upon UV and/or blue excitation) with does not extend far in the red and has a cutoff at a relative short wavelength (compared to most of the state of the art red luminescent materials similar to formula I phosphors).

The above described organic luminescent material is of the perylene type. Perylenes are known in the art and are for instance described in US 4,845,223, US

2003/011 1649, WO 2010/1 16294 (Incorporated herein by reference), and WO 2012/1 13884.

The phrase "at least two selected from G2, G3, G4, and G5 at least comprise X, wherein independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine" indicates amongst others that from the four groups G2, G3, G4, and G5, at least two of these, but in embodiments also three of these, or all of these, comprise a group X as defined herein. Especially, two of these, or in embodiments three or all four of these, are X. From this group of at least two X groups, at least two X groups are each independently at least substituted with one fluroine or chlorine, especially at least substituted with one fluorine. This may thus include embodiments where two of G2-G5 comprise X, or even especially are X, with each of them one or more halogen substitutions, but this may also include embodiments where three or four of G2-G5 comprise X, or even especially are X, with two of the three, or three of the three, or two of the four, or three of the four, or four of the four, respectively, are substituted with one or more halogens. In an embodiment, two of G2-G5 comprise

(especially consist of) X. in yet another embodiment, four of G2-G5 comprise (especially consist of) X. Hence, the phrase "at least substituted with one fluorine" and similar phrases may indicate that there is at least one substituent F, though there may (thus) be more. As indicated above, the available X-groups in two or more of G2, G3, G4, and G5, may especially comprise two or more groups selected from fluorine and chlorine, i.e. contain two or more halogen substituents.

The phrase "independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine" also indicates that the X groups available are independently of each other substituted. Hence, one of the X groups may e.g. have a fluorine at the D or M position and one of the X groups may have a fluorine at the E or L position, or a chlorine at one more of the D,E,I,L,M position, etc. Especially, the two groups that at least comprise X, or more espeically the two groups that in an embodiment are X, are identical. When the four groups comprise X, or are X, especially there are two sets of identical X, but the sets are mutually different, or there is one set of identical X (all four G2-G5 are identical).

It appears that with the inclusion of a halogen in X the emission wavelength shifts to the blue (less far red). For instance, including two X groups each comprising one fluorine substitution, there may be a blue shift of about 10 run relative to the unsubstituted X groups. With two X groups each comprising two fluorine substitutions, the shift to the blue may be in the range of 20 nm relatieve to the unsubstituted X groups. Hence, in a specific embodiment independently at least two of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise groups selected from fluorine and chlorine. Hence, assuming 2-4 of G2-G5 comprising, or especially consisting of X, at least two of these (i.e. two of two, two of the three, or three of the three, or two of the four, or three of the four, or four of the four) have two or more halogen groups. The distribution of these two or more halogens over D, E, I, L and M for each of these at least two G2-G5 may independently be chosen. However, as indicated above, when the two groups at least comprise X, or more espeically, when two groups are X, these two groups are in an embodiment especially identical. When the four groups comprise X, or are X, especially there are two sets of identical X (especialy one or more of G2=G5 and G3-G4 applies), but the sets are mutually different, or there is one set of identical X (all four G2-G5 are identical).

In an embodiment, the following conditions apply: (I) with respect to Y: (la) A,C = isopropyl and B,J,Q = hydrogen; or (lb) A,Q = t-butyl and B,J,C = hydrogen; and (II) with respect to X: (Ila) D,M = isopropyl and E,I,L = hydrogen or (lib) one or two of

D,E,I,L,M = fluorine or chlorine and the remaining hydrogen. This is indicated in below table: Y X

A B C J Q D E I L M

la isopropyl H isopropyl H H Ila isopropyl H II H isopropyl la isopropyl H isopropyl H H lib one or two of D,E,I,L,M = fluorine or chlorine and the remaining hydrogen lb t-butyl H H t- Ila isopropyl H H H isopropyl butyl

lb t-butyl H H H t- lib one or two of D,E,I,L,M = fluorine or butyl chlorine and the remaining hydrogen

The options Ila and lib especially independently apply to at least two of G2, G3, G4 and G5, More especially, the conditions lib especially apply to at least two, especially all four, of G2, G3, G4 and G5 (i.e. at least two of G2, G3, G4 and G5 are X, with the conditions lib).

Note that such conditions for Y may apply to one or both Y groups. The conditions for X may apply to both X comprising groups selected from G2-G5, but may optionally apply to three or four of these four groups. This also applies for the below indicated embodiments. In a specific embodiment, two of the groups G2,G3, G4 and G5 are hydrogen and the two X comprising groups are identical.

In a further specific embodiment, G2=G5= X, with D=E= F and I=L=M= hydrogen, and wherein G 1 =G6 = Y, with A=C= isopropyl and B=J -Q= hydrogen. This is a specifc embodiment of the combination I a- 1 lb as indicated in the table. Such embodiment may especially show a desired luminescence.

Likewise, a further desired embodiment is wherein G2=G3=G4=G5 are X, with at least one of A or B is a fluorine or chlorine, and wherein C,J,Q are independently selected from F, CI, or H.

Alternatively, G2-G5- X, with D=E= F and I=L=M= hydrogen, and wherein G 1 =G6 = Y, with at least one of A or B is a fluorine or chlorine, and wherein C J,Q are independently selected from F, CI, or H. In such embodiment, G3 and G4 may especially be hydrogen.

Alternatively, G2=G4= X, with D=E= F and I=L=M= hydrogen, and wherein G1=G6 = Y, with at least one of A or B is a fluorine or chlorine, and wherein C,J,Q are independently selected from F, CI, or H. In such embodiment, G3 and G5 may especially be hydrogen. Another specific embodiment is wherein G2=G5= X, with D=E= F and I=L=M= hydrogen, and wherein G1-G6 = Y, with A=C= isopropyl and B=J=Q= hydrogen. In such embodiment, G3 and G4 may especially be hydrogen.

Alternatively, G2=G4= X, with D=E= F and I=L=M= hydrogen, and wherein G1 =G6 = Y, with A=C= isopropyl and B=J=Q= hydrogen. In such embodiment, G3 and G5 may especially be hydrogen.

With respect to Gl and G6, it may be advantageseous (with respect to optical properties (of especially the light converter)) when either A=C= isopropyl and B=J=Q= hydrogen, or when A=Q= t-butyl and B=J=C= hydrogen.

The red emitting (organic) luminescent material preferably emits 70% of the energy (Watt) below 650 nm (at RT), even more especially at least 70% of the energy below 645 nm (at RT).

The above described organic luminescent material may be well excitable in the blue and/or UV and/or even in the green and/or yellow. Hence, in further embodiments, the organic luminescent material may be excited by a source of blue light, such as a blue LED light source, but alternatively or additionally, the organic luminescent material may also be excited by a source of green and/or yellow light. Examples of the latter may e.g. green and/or yellow emitting luminescent materials like cerium containing garnet systems (such as YAG:Ce; see also below) or an organic yellow emitter.

In a further aspect, the compound herein indicated with reference 17 (see also fig. 2b) is used in a remote (from the light source) configuration. In yet another embodiment, the compound herein indicated with reference 17 is embedded in a matrix comprising PET. Especially, this PET matrix may be arranged remote (from the light source / source of light).

In a specific embodiment, one or more of Gl , G2, G3, G4, G5, and G6, especially one or more of Gl and G6, comprise a covalent link with the matrix. This may for instance be obtained by providing one or more of these groups, such as one or more of Gl and G6, with a curable group or a polymerizable group. As indicated above, the matrix may e.g. PMMA or PET, especially PET.

The term "formula (1)" may also be indicated as "chemical formula (I)".

However, the light converter may also comprise a plurality of organic luminescent materials according to formula I. Hence, in an embodiment, the term "organic luminescent material" may relate to a combination of different organic luminescent material all complying with formula (I). Further, the light converter optionally comprises an inorganic luminescent material (see further below). However, the light converter may also comprise a plurality of inorganic luminescent materials. Hence, in an embodiment the light converter may comprise one or more organic luminescent materials according to formula I, and optionally one or more other organic luminescent materials, and preferably one or more inorganic luminescent materials. The light converter may further comprise one or more scattering materials (e.g. Ti0₂, AI2O3 and/or BaSO.; particles) , and optionally other materials.

In a specific embodiment, two of the groups G2,G3, G4 and G5 are hydrogen and the two X comprising groups are identical, the inorganic luminescent material comprises a quantum dot based luminescent material, and the matrix comprises polyethylene

terephthalate (PET) (see also above).

In a variant, at least two selected from G2, G3, G4, and G5 at least comprise X, wherein independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group as defined above, including optionally, but not necessarily, selected from fluorine and chlorine. Hence, in such variant, one or more of G2, G3, G4, and G5 may be halogen free. For instance, for each of G2, G3, G4, and G5 (at least comprising X) one or more of D, E, I, L and M may comprise independently comprise a group selected from hydrogen, isopropyl, t-butyl, methoxy, alkyl with up to 16 carbon atoms, and an oxygen-containing alkyl with up to 16 carbon atoms. Other perylene derivatives may be of interest as well.

It is further referred to US patent application 61/763025, filed February 11' 2013, and European patent application 13175123.2, filed July 4, 2013. which are

incorporated herein by reference.

Other organic luminescent materials that may be applied, such as those that do not include halogenated groups are indicated below. For instance, in an embodiment the organic luminescent material is selected from the group comprising:

As indicated above, also a combination of two or more different organic materials may be applied.

In addition to the above-mentioned organic luminescent material the lighting device may further comprise a second luminescent material. This second luminescent material is not necessarily comprised by the light converter. However, in an embodiment, the second luminescent material is comprised by the light converter. In an embodiment, the second luminescent material comprises a second organic luminescent material. For such second organic luminescent material the same conditions and (preferred) embodiments as described herein for the (first) organic

luminescent material may apply. Hence, in a specific embodiment the second (organic) luminescent material is configured to provide upon excitation with the light source light

(second) luminescent material light having a wavelength within the visible wavelength range, wherein the second (organic) luminescent material has an excitation spectrum having a maximum excitation intensity at a third wavelength (λ3), and wherein λ\≠ 13.

However, additionally or alternatively, the second luminescent material comprises an inorganic luminescent material, such as one or more of a cerium doped garnet material and a quantum dot based material. Again, as indicated above, also combinations of two or more luminescent materials may be applied. Such luminescent materials may be applied as adjacent layers or as mixtures. However, they may also be arranged remote from each other. In addition to the one or more organic luminescent materials, also other luminescent materials may be applied. The other luminescent material may be contained in the matrix as well. Alternatively or additionally, the other luminescent material may be present as coating on the light converter. Alternatively or addtionally, the luminescent material may be arranged anywhere else in the lighting device. Also the other luminescent mateiral may especially be configured to convert at least part of the light source light into visible converter light. Especially, the other luminescent material is configured to provide one or more of blue, green, yellow and orange light, more especially at least one or more of green and yellow light. Several options are possible, including

(Ca,Sr,Ba)(Al,Ga,ln)₂(0,S,Se)4:Eu , a thiogallate, especially such luminescent material at least composing Sr, Ga and S, such as SrGa₂S : Eu . These type of luminescent materials may especially be narrow band green emitters. Optionally or alternatively, the other luminescent material may comprise a

(garnet material), wherein M is selected from the group consisting of Sc, Y, Tb, Gd, and Lu. wherein A is selected from the group consisting of Al and Ga. Preferably, M at least comprises one or more of Y and Lu, and wherein A at least comprises AL These types of materials may give highest efficiencies. Embodiments of garnets especially include M3A5O12 garnets, wherein M comprises at least yttrium or lutetium and wherein A comprises at least aluminum. Such garnet may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with at least Ce. Particularly suitable luminescent materials, however, are Ce doped Yttrium aluminium garnet (YAG, Υ3ΆΙ5Ο12) and Lutetium- Aluminium-Garnet (LuAG).

Additionally or alternatively, the other luminescent material may comprise one or more of selected from the group consisting of divalent europium containing nitride luminescent material or a divalent europium containing oxonitride luminescent material, such as one or more materials selected from the group consisting of (Ba,Sr,Ca)S:Eu,

(Mg,Sr,Ca)AlSi ^T3:Eu and (Ba,Sr,Ca)2Si5N₈:Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation, especially in the range of about 0.5-10%, more especially in the range of about 0.5-5% relative to the cation(s) it replaces. The term ": Eu" or ":Eu²⁺", indicates that part of the metal ions is replaced by Eu (in these examples by Eu²⁺). For instance, assuming 2% Eu in CaAlSiNj :Eu, the correct formula could be (Cao ^Euo o.?)AlSi 3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba. The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca);

especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Further, the material

can also be indicated as wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and/or Ba.

As second luminescent material, also quantum dot based materials may be applied, or other (inorganic) luminescent materials may be applied. Hence, in an embodiment the second luminescent material comprises one or more materials selected from the group comprising quantum dots, quantum rods or quantum tetrapods, nano-crystals, a rare earth metal based luminescent material, and an inorganic luminescent material. The may be configured to show line emission (f-f transitions) and/or broad band emission(s) (f-d transitions). Additionally or alternatively, the second luminescent material comprises an inorganic luminescent material. The inorganic luminescent material may comprise quantum Dots (QDs). Amongst other narrow band emitters quantum dots are highly suitable for this purpose. Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. This means that by using quantum dots any spectrum can be obtained as they are narrow band emitters.

Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CulnS2) and/or silver indium sulfide (AgInS₂) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore, the emission color can easily be tuned by adapting the size of the quantum dots.

The quantum dots or luminescent nanoparticles, which are herein indicated as light converter nanoparticles, may for instance comprise group II- VI compound

semiconductor quantum dots selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS. CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe. In another embodiment, the luminescent nanoparticles may for instance be group III-V compound semiconductor quantum dots selected from the group consisting of GaN, GaP, GaAs, A1N, A1P, AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, A1NP, AINAs, AlPAs, In P, InN As, InP As, GaAlNP, GaAlNAs, GaAlPAs, Galn P,

GalnNAs, GalnPAs, InAlNP, InAlNAs, and InAlPAs. In yet a further embodiment, the luminescent nanoparticles may for instance be I-III-VI2 chalcapyrite-type semiconductor quantum dots selected from the group consisting of CulnS₂, CuInSe₂, CuGaS₂, CuGaSe₂, AglnSi, Agln5e₂, AgGaS₂₎ and AgGaSe₂. In yet a further embodiment, the luminescent nanoparticles may for instance be I-V-VI2 semiconductor quantum dots, such as selected from the group consisting of LiAsSe₂, NaAsSe₂ and KAsSe₂. In yet a further embodiment, the luminescent nanoparticles may for instance be a group IV-VI compound semiconductor nano crystals such as SbTe. In a specific embodiment, the luminescent nanoparticles are selected from the group consisting of InP, CuInS₂, CuInS¾, CdTe, CdSe, CdSeTe, AglnS? and AglnSe₂. In yet a farther embodiment, the luminescent nanoparticles may for instance be one of the group II-VI, III-V, I-III-V and IV-VI compound semiconductor nano crystals selected from the materials described above with inside dopants such as ZnSe:Mn, ZnS:Mn. The dopant elements could be selected from Mn, Ag, Zn, Hu, S, P, Cu, Ce, Tb, Au, Pb, Tb, Sb, Sn and Tl. Herein, the luminescent nanoparticles based luminescent material may also comprise different types of QDs, such as CdSe and ZnSe:Mn. It appears to be especially advantageous to use II-VI quantum dots. Hence, in an embodiment the semiconductor based luminescent quantum dots comprise II-VI quantum dots, especially selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTc, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CriZnS, CdZnSe, CdZnTe, Cdi lgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, even more especially selected from the group consisting of CdS, CdSe, CdSe/CdS and CdSe/CdS/ZnS.

In an embodiment, Cd-free QDs are applied. In a specific embodiment, the light converter nano-particles comprise III-V QDs, more specifically an InP based quantum dots, such as a core-shell InP-ZnS QDs. Note that the terms "InP quantum dot" or "InP based quantum dot" and similar terms may relate to "bare" InP QDs, but also to core-shell InP QDs, with a shell on the InP core, such as a core-shell InP-ZnS QDs, like a In -ZnS QDs dot-in- rod.

In an embodiment, nanoparticles can comprise semiconductor nan crystals including a core comprising a first semiconductor material and a shell comprising a second semiconductor material, wherein the shell is disposed over at least a portion of a surface of the core. A semiconductor nanocrystal including a core and shell is also referred to as a "core/shell" semiconductor nanocrystal.

For example, the semiconductor nanocrystal can include a core having the formula MX, where M can be cadmium, zinc, magnesium, mercury, aluminum, gallium, indium, thallium, or mixtures thereof, and X can be oxygen, sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony, or mixtures thereof. Examples of materials suitable for use as semiconductor nanocrystal cores include, but are not limited to, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe, GaAs, GaN, GaP, GaSe, GaSb, HgO, HgS,

HgSe, HgTe, InAs, InN, InP, InSb, AlAs, A IN, A1P, AlSb, TIN, TIP, TIAs, TISb, PbO, PbS, PbSe, Pb^'fe, Ge, Si, an alloy including any of the foregoing, and/or a mixture including any of the foregoing, including ternary and quaternary mixtures or alloys.

The shell can be a semiconductor material having a composition that is the same as or different from the composition of the core. The shell comprises an overcoat of a semiconductor material on a surface of the core semiconductor nanocrystal can include a Group IV element, a Group II-VI compound, a Group II-V compound, a Group III- VI compound, a Group III-V compound, a Group IV- I compound, a Group I-III-VI compound, a Group ll-IV-VI compound, a Group II-IV-V compound, alloys including any of the foregoing, and/or mixtures including any of the foregoing, including ternary and quaternary mixtures or alloys. Examples include, but are not limited to, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, MgS, MgSe, GaAs, GaN, GaP, GaSe, GaSb, HgO, HgS, HgSe, HsTe, InAs, inN, InP, InSb, AlAs, AIN, A1P, AiSb, TIN, TIP, TIAs, TISb, PbO, PbS, PbSe, PbTe, Ge, Si, an alloy including any of the foregoing, and/or a mixture including any of the foregoing. For example, ZnS, ZnSe or CdS overcoatings can be grown on CdSe or CdTe semiconductor nanocrystals.

Examples of semiconductor nanocrystal (core)shell materials include, without limitation: red (e.g., (CdSe)ZnS (core)shell), green (e.g., (CdZnSe)CdZnS (core)shel!, etc.), and blue (e.g., (CdS)CdZnS (core)shell (see further also above for examples of specific light converter nanoparticles, based on semiconductors.

Therefore, in a specific embodiment, the light converter nanoparticles are selected from the group consisting of core-shell nano particles, with the cores and shells comprising one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS. CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgScTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, I lgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgS eS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, GaN, GaP, GaAs, AIN, AIP, AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AINP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaA As, GaAlPAs, GalnNP, GalnNAs, GalnPAs, InAlNP, InAlNAs, and InAlPAs.

In general, the cores and shells comprise the same class of material, but essentially consist of different materials, like a ZnS shell surrounding a CdSe core, etc.

When a combination of two or more luminescent materials is applied, and when there are one or more organic luminescent materials, embodiments of the lighting device may be configured to substantially prevent that the one or more organic luminescent materials are excited in their maximum. Especially, all one or more organic luminescent materials are excited off-maximum. Even more especially, all one or more organic luminescent materials are directly excited by a light source, such as a LED, and are not substantially excited by another (organic) luminescent material. The lighting device may include specific sets of one or more organic luminescent materials and sources of light, such that each set is optimized with respect to excitation wavelength and light source light.

The lighting device may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, green house lighting systems, horticulture lighting, or LCD backlighting. The invention also provides in a further aspect a luminaire comprising a lighting device as defined herein.

As indicated above, the lighting device may be used as backlighting device in an LCD display device. Hence, the invention provides also a LCD display device comprising the lighting device as defined herein, configured as backlighting device. The invention also provides in a ftirtlier aspect a liquid crystal display device comprising a back lighting device, wherein the back lighting device comprises one or more lighting devices as defined herein.

The term "substantially" herein, such as in "substantially all light" or in "substantially consists", will be understood by the person skilled in the art. The term

"substantially" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term "comprise" includes also embodiments wherein the term "comprises" means "consists of. The term "and/or" especially relates to one or more of the items mentioned before and after "and/or". For instance, a phrase "item 1 and/or item 2" and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, arid that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figs, la-l f schematically depict some embodiments of the lighting device; these drawings are not necessarily on scale;

Figs. 2a-2j schematically depict some organic materials that were made;

Figs. 3a-3b show some emission spectra of some of these organic materials; Figs. 4a-4b schematically show some synthesis schemes;

Fig. 5 schematically shows different excitation options;

Fig. 6a-6c schematically show some excitation spectra and an emission spectrum of a number of organic luminescent materials;

Figs. 7a-7d schematically depict several configurations as well as the impact on the stability. DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 a schematically depicts a lighting device 1 with a light converter 100, which in this embodiment at least comprises the organic luminescent materia! 140 according to formula I. The organic luminescent material 140 is in this embodiment embedded in a (polymeric) matrix, such as PET. As can be seen, a remote version is shown, with a non-zero distance d between the luminescent material (in the light converter 100) and the light source(s), indicated with reference(s) 10. The lighting device 1 comprises one or more light sources 10 which are configured to provide light source light 1 1, especially blue and/or UV light. The lighting device 1 may comprise a plurality of such light sources. When lighting device light, indicated with reference 2, of a white nature is desired, it may be necessary to us an RGB concept, wherein the red color, or at least part thereof, is provided by the red luminescent material 140, and the blue and green light are provided by one or more of the light source and a combination of the light source and another luminescent material, especially the inorganic luminescent material. The inorganic luminescent material is indicated with reference 130, and provides inorganic luminescent material light 131.

The organic luminescent material 140 according to formula I provides upon excitation by the light source light 1 1 and/or by emission of one or more other luminescent materials, such as e.g. the inorganic luminescent material light 131 , organic luminescent material light 141. Here, the light converter 100 is remote from the light source 10, and the organic luminescent material, which is embedded in the light converter 100, is thus also remote. The optional inorganic luminescent material 130 can also be arranged remote, see below, but is by way of example close to the light source 10, such as in a dome and/or as layer on the LED die.

Just by way of example, one light source has been depicted without the inorganic luminescent material 130. However, in another embodiment, all light sources 10 may be configured with at least inorganic luminescent material 130. Also, by way of example three light sources 10 have been depicted. However, more or less than three light sources may be applied.

Note that the light source 10 may provide blue and/or UV light. The inorganic luminescent material 130 may especially, upon excitation (by said light of the light source 10) provide one or more of blue, green, and yellow light. Optionally, the inorganic iuminescent material 130 may also provide red light, but especially the inorganic luminescent material 130 has a cutoff equal to or below 600 run (such as especially having a spectral distribution with at least 70% of the energy below 600 nm). Fig. l a, and other figures, schematically depict a device with a light chamber 170, with an enclosure 171, at least partly enclosing a cavity 172, which has a transmissive part 173.

Especially, the reflectivity (except for a transmissive part or window) of the mixing chamber is preferably > 80%, more preferably 90%, most preferably > 95%, especially for light in the visible. This may also apply for other herein described and/or schematically depicted embodiments.

In an embodiment, the transmissive part 173 comprises the light converter 100, or may especially consist of the light converter 100. The surface of the non-transmissive part of the enclosure is indicated with reference 171. At least part of the surface 171 may comprise a reflector, such as a reflective coating.

The light converter 100 provides upon excitation light converter light 1 1 1 , which at least comprises organic luminescent material light 141 but may optionally comprise other luminescence light as well (see below). The lighting device light, indicated with reference 2, at least comprises light converter light 1 1 1 / organic luminescent material light 141 , but may optionally comprise one or more of the light source light 1 1 , inorganic luminescent material light 131 , and light of other luminescent materials (not depicted).

Fig. 1 b schematically depicts an embodiment wherein the light converter 100 may comprise an upstream layer with inorganic luminescent material 130. Optionally, this may be a light converter comprising two layers comprising the same matrix, but comprising different luminescent materials. The distance of the layer with inorganic luminescent material 130 to the light source is indicated with dl . This distance is in this embodiment non-zero, in contrast to the embodiment schematically depicted in fig. l a. The terms "upstream" and "downstream" relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the first source of light), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is "upstream", and a third position within the beam of light further away from the light generating means is

"downstream".

Fig. l c schematically depicts an embodiment wherein the light converter 100 comprises the inorganic luminescent material 130, e.g. in the form of quantum dots, and the organic luminescent material 140 according to formula I. Both the organic luminescent material 140 and the inorganic luminescent material 130 are in this embodiment embedded in the (remote) light converter, i.e. embedded in the (polymeric) matrix of the light converter 100, Figs, lb and lc schematically show embodiments in a transmissive configuration, i.e. with the source of light at one side of the light converter and lighting device light escaping at the other side of the light converter.

Fig, Id schematically depicts an embodiment wherein the transmissive part 173 comprises at least two types of segments, with volumes over 0.25 cm³, wherein the two types of segments comprise different weight ratios organic luminescent material and inorganic luminescent material. For instance, first segments only comprise the organic luminescent material 140 as luminescent material and second segments only comprises inorganic luminescent material 130 as luminescent material. The organic luminescent material 140 may also in this embodiment be embedded in a (polymeric) matrix, such as PET. Likewise, also the inorganic luminescent material 130 may be embedded in a

(polymeric) matrix, such as PET.

Fig. 1 e schematically depicts an embodiment wherein the enclosure 170 comprises a transmissive diffuser 160 (as transmissive part 173) and the light converter is applied to at least part of the non-transmissive part of the enclosure 171 . Here, the light converter 100 is arranged in a reflective configuration.

Fig. If schematically depicts a reflective configuration. As mentioned above, the organic luminescent material 140 and optionally the inorganic luminescent material 140 may (both) be embedded in a (polymeric) matrix. Here, the light converter 100 is arranged in a reflective configuration.

Figs. 2a-2j schematically depict some organic luminescent material that have been made of the perylene type, especially embodiments of the organic luminescent material 140. Especially molecules 68, 65, 53, 52, 63, 64, xl, and x2 are desired because of their optical properties, especially those having at least two halogen atoms at each X group. Optical properties of some of the luminescent materials are shown in figs. 3a and 3b. These graphs show emission spectra, with amongst others emission curve of material 2 as comparison. When measuring the spectral distribution of the emission energy (power) as a function of the emission wavelength under 450 nm excitation in the range up to 750 run, then the ratio of e.g. below 645 nm emission to the total emission can be calculated.

Most of the materials were made according to scheme 1 depicted in fig. 4a or according to scheme 2 depicted in fig. 4b. EXAMPLES

Synthesis of 53. See scheme l .N,N^?-Bis-(2,6-diiso ropylphenyl)-l ,6J,12- tetrachloroperylene-3 ,4,9, 10-tetracarboxdiimide B.

l ,6,7, 12-Tetrachloroperylene-3,4:9, 10-tetracarboxylic dianhydride; (A, 10.0 g, 19.0 mmol) was finely suspended in propionic acid (250 mL). Then, 2,6-diisopropylaniline

( 16.7 g, 40 mmol) was added and the mixture was refiuxed under nitrogen for 17 fa. After cooling to room temperature, water was added to the mixture and the precipitate was filtered, washed extensively with water and then with heptane and dried under vacuum to give 9 g (56% yield) of compound B as an orange solid.

N,N'-Bis(2,6-diisopropylphenyl)- l , 6,7, 12-tetra(3-fluorophenoxy)perylene- 3,4:9, 10-tetracarboxdiimide 53.

A mixture of A', N'-Bis-(2,6-diisopropylphenyl)- 1 ,6,7, 12-tetrachloroperylene-

3,4,9,10-tetracarboxdiimide (B, 4 g, 4,7 mmol), 2-fluorophcnol (2.5 mL, 28.2 mmol) and K;>CC>3 (4.3 g, 31.0 mmol) in NMP (80 mL) was stirred at 1 10°C under nitrogen for 3h. Then, the contents of the flask were poured into a mixture of water and acetic acid and stirred for 2h and the precipitated solid was filtered, washed neutral with warm water and vacuum dried at 60°C. The compound was recrystallized from methanol then from a EtOAc / heptanes mixture (2 x) then from a DCM / heptanes mixture (3 x) and the red solid collected was washed with warm heptane and dried under vacuum. Pure compound 53 (1.6 g, 1 % yield) was obtained as a red solid. ¹⁹F-NMR (282 MHz, in CDC¾): 8=4 l Oppm. Mass (TOF-ESI, m/z): Calculated for

1 151.39, Found: 1 151.61. _max (ethyl

acetate)=558nm, ε=45600. λ (em) (ethyl acetate) 586nm.

Molecule 53 is depicted in fig. 2D. As can be seen form this figure, at least two selected from G2, G3, G4, and G5 at least comprise X, wherein independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine. Here, G2, G3, G4 and G5 comprise X, with each of these four comprise a (single) fluorine. Note that not necessarily all four of G2, G3, G4 and G5 comprise identical groups.

Synthesis of N,N^,-Bis(2,6-diisopropylphenyl)-l ,6,7,12-tetra(2,3-difluorgphenoxy) ...perylene- 3.4.9.10-tetracarboxdiimide 65. See scheme 1.

A mixture of A^* /V'-Bis-(2,6-diisopropylphenyl)- l ,6,7, 12-tctrachioroperylene-

3, 4,9, 10-tetracarboxdiimide (B, 5.4 g, 6.4 mmol), 2,3-difluorophenol (5.0 g, 38.4 mmol) and ₂C0₃ (5.7 g, 41 ,6 mmol) in NMP (100 niL) was stirred at 110°C under nitrogen for 5h. Then, the contents of the flask were poured into acetic acid. After 2 minutes, 2 N aqueous HC1 was added and stirred for 10 minutes and the precipitated solid was filtered, washed neutral with warm water and vacuum dried at 60°C. The residue was coated on silica gel and purified by column chromatography (Si0₂, eluent: DCM/Heptane 1/1). The compound was purified again by two recrystallizations from methanol then from a DCM / heptanes mixture (3 x). The red solid collected was washed with warm heptane and dried under vacuum. Pure compound 65 (2.1 g, 27% yield) was obtained as a red solid. ^{I 9}F-NMR (282 MHz, in CDCI3): δ =-154ppm and δ =- 1 35ppm. Mass (TOF-ESI, m/z): Calculated for C₇2H5 iF₈N₂0g⁺ ([M- H]⁺): 1223.36, Found: 1223.29. (ethyl acetate)=548nm₅ ε =53400. λ (em) (ethyl acetate) 576nm.

Molecule 65 is depicted in fig. 2C. As can be seen form this figure, at least two selected from G2, G3, G4, and G5 at least comprise X, wherein independently at least one of D, E, 1. L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine. Here, G2, G3, G4 and G5 comprise X, with each of these four comprise a fluorine (in fact each comprise two fluorine substituents). Note that not necessarily all four of G2, G3, G4 and G5 comprise identical groups.

Synthesis of N.N'-Bis(2.6-diisopropvlphenvl)- 1.6.7.12-tetra(^'2.6-difluorophenoxv) pervlene- 3A J 0-tetracarboxdiimide 71. See scheme 1.

A mixture of NN-Bis-(2,6-diisopropylphenyl)- 1,6,7, 12-tetrachloroperylene- 3,4,9, 10-tetracarboxdiimide (B, 4.2 g, 5.0 mmol), 2.6-dit uorophcnol (5.0 g, 38.4 mmol) and K2CO3 (5.3 g, 38.4 mmol) in NMP (80 iriL) was stirred at 1 10°C under nitrogen overnight. Then, the contents of the flask were poured into a cold 20% acetic acid solution in water. After 5 minutes, 2 N aqueous HCl was added and stirred for 10 minutes and the precipitated solid was filtered, washed neutral with warm water and vacuum dried at 60°C. The residue was coated on silica gel and purified by column chromatography (Si<¾, eluent:

DCM/Heptane 2/1 ). The compound was purified again by a recrystallization from methanol then from a DCM / heptanes mixture (3 x). The red solid collected was washed with hot heptane and dried under vacuum. Compound 71 (3.5 g) was obtained as a red solid. ¹⁹F-NMR (282 MHz, in CDCI₃): δ—126 ppm. Mass (TOF-ESI, m/z): Calculated for

([M-Hf^' ): 1223.36, Found: 1223.86. λ,_ωχ (ethyl acetate)=556nm, ε =60460. λ (em) (ethyl acetate) 576nm. Compound 71 is depicted as compound XI in fig. 21. Synthesis of N,N^,-Bis(2,6-diisopropylphenyl)-l,6,7,12-tetra(2,5-dichlorophenoxy) perylene- 3.4.9.10-tetracarboxdiimide 72. See scheme 1.

A mixture of NN^'-Bis-(2,6-diisopropylphenyl)- 1 ,6,7.12-tetrachloroperylene- 3,4,9, 1 Q-tctracarboxdiimide (B , 4.0 g, 4.7 mmol), 2,5-dichlorophenol (5.0 g, 30.5 mmol) and K₂C0₃ (4.3 g, 31.0 mmol) in NMP (80 ml.) was stirred at 1 10°C under nitrogen overnight. Then, the contents of the flask were poured into a cold 20% acetic acid solution in water. After 5 minutes, 2 N aqueous HQ was added and stirred for 10 minutes and the precipitated solid was filtered, washed neutral with warm water and vacuum dried at 60°C. The residue was coated on silica gel and purified by column chromatography (SiO% eluent:

DCM/Heptane 1/1 to 2/1). The compound was purified again by a recrystallization from a DCM / heptanes mixture (3 x). The red solid collected was washed with hot heptane and dried under vacuum. Compound 72 (1.5 g) was obtained as a red solid. Mass (TOF-ESI, m/z): Calculated for

([ -H] ^'): 1355.1 1 (100%), Found: 1355.36 (100%). λ™* (ethyl acetate)=550nm, ε =47430. λ (em) (ethyl acetate) 576nm. Compound 72 is depicted as compound X2 in fig. 2J.

Synthesis of 68. See scheme 2.

1.7,-dibromoperylene-3,4,9, 10-letracarboxylic dianhydride D. , Perylene- 3,4,9, 10-tetracarboxylic dianhydride C (40.0 g, 101.9 mmol), iodine (1 .0 g, 4.0 mmol) and sulphuric acid (96%, 470 mL) was premixed and stirred for 2 h at room temperature. The reaction temperature was set to 80°C and bromine (15.5, 301.7 mmol) was added dropwise. The mixture was reacted further at 80°C for 20 h. The reaction mixture was cooled to room temperature and the excess Br? was displaced by nitrogen. The product was precipitated by addition of ice-water and collected by filtration. The precipitate was washed with water several times until the aqueous layer became neutral. Drying in the oven at 60°C for 3 days gave crude product used for the next step without further purification.

NN'-Bis-(2,6-diisopropylphenyl)-l ,7,-dibromoperylene-3,4,9, 10- tetracarboxdiimide E. A mixture of 1 , 7, -dibromoperylene-3,4,9, 10-tetracarboxylic dianhydride D (see above), 2,6-diisopropylaniline (41.5 mL, 220 mmol) in propionic acid (1 L) and NMP (500 mL) was retluxed for 2,5 days under nitrogen. The mixture was cooled to RT and the product was precipitated by addition of water and collected by filtration. The precipitate was washed with water several times until neutral and dried. The product was first purified by column chromatography (SiCb, eluent: DCM Heptane 2/1 to DCM) to obtain a mixture of the isomeric diimides. The mixture was washed with EtOH (300 mL) and toluene (300 mL) and then heated at 80°C in toluene (300 mL) over night, The diimide 2386 was recrystallized from the hot toluene solution. The solid was collected through hot filtration and dried under vacuum to give compound 3 (18 g, 20% yield) as an orange powder. N,N'-Bis(2,0-diisopropylphenyl)~l ,7-bis(2.3-difluorophenoxy) pervlene-3.4.9, 10- tetracarboxdiimide 68.

A mixture of N,N'-Bis-(2,6-diisopropylphenyl)-l,7,-dibromoperylene-3,4,9,10- tetracarboxdiimide (E, 1.5 g, 1 ,7 mmol), 2,3-difluorophenol (675 mg, 5.2 mmol) and ₂C(¾

(956 mg, 6.9 mmol) in NMP (70 mL) was stirred at 1 10°C under nitrogen for 5h. Then, the contents of the flask were poured into acetic acid. After 2 minutes, 2 N aqueous HC1 was added and stirred for 10 minutes and the precipitated solid was filtered, washed neutral with warm water and vacuum dried at 60°C. The residue was coated on silica gel and purified by column chromatography (Si0₂, eluent: DCM/Heptane 1/1). The compound purified again by two recrystallization from a DCM / heptanes mixture (3 x). The red solid collected was washed with warm heptane and dried under vacuum. Pure compound 68 ( 770 mg, 47% yield) was obtained as a red solid. ¹⁹F-NMR (282 MHz, in CDC1₃): δ =-155ppm and δ =- 134ppm. Mass (TOF-ESI, m ^'y. Calculated for C72H₅iF_sN₂( ([ -Hf): 967.33, Found: 967.30. X _max (ethyl acetate)=528nm, ε =57200. λ (em) (ethyl acetate) 550nm.

Molecule 68 is depicted in fig. 2A. As can be seen form this figure, at least two selected from G2, G3, G4, and G5 at least comprise X, wherein independently at least one of D, E, I, L and M of at least two of said at least two selected from G2, G3, G4, and G5 comprise a group selected from fluorine and chlorine. Here, G2 and G5 comprise X, with each of these two comprise a fluorine (in fact each comprise two fluorine substituents).

As indicated above, it was surprisingly found that the bleaching depends on the absorbed light per molecule. Thus when the molecules are irradiated at a wavelength where the extinction coefficient is higher the lifetime of the molecule decreases. Fig. 5 shows in the upper part an excitation (EX) and emission (EM) spectrum of a schematical system. In the lower curve, different options (non-exhaustive) or shown of different types of excitation of a source of light, such as a LED or laser diode. Curve "a" substantially overlaps with the excitation curve. A shift of the curve, as shown with curves "b" and "c" will lead to a sub- optimal overlap of the curves. On the y-axis the intensity and on the x-axis the wavelength is indicated. When the organic molecules are irradiated at a wavelength where their extinction coefficient is lower the lifetime of the molecule increases. It is therefore suggested using molecules and configurations for decreasing the absorbed light per molecule.

In a first embodiment, we suggest molecules with a low extinction coefficient at the wavelength of absorption, i.e. situations wherein the source of light and organic luminescent material is chosen such that the excitation light of the source of light is not in the maximum of the excitation curve of the organic luminescent materials as is the case with curves a and c in fig. 5. In a specific embodiment, the light source emission peak is substantially in between the phosphor absorption peak and the phosphor emission peak (Fig. 5, curve c).

Note that the source of light, of which by way of example some potential emission curves are shown in the lower part of fig, 5, may in an embodiment be electronic light sources, such as LED or laser light sources. However, optionally such source(s) of light may also be one or more other (organic) luminescent materials.

In order to show the effect of extinction coefficient one can compare the lifetime of a molecule irradiated using various sources having the same intensity. We shall use spectral overlap for a given molecule irradiated using various sources as a measure of dose/per molecule. Spectral overlap (SO) for a given molecule is defined as

Here Ι(λ) is the intensity of the light source as a function of wave length and ε( λ) is the extinction coefficient as a function of wavelength and z_mm corresponds to the maximum extinction coefficient (derived from the excitation spectrum of the organic luminescent material). λ_χ and Xy defines the wavelength range for the integral and it corresponds to the range of the emmision and excitation spectra. In the table below the values for the overlap integral is calculated using the equation above.

There is a clear relation between spectral overlap and lifetime (for the same molecule), see the Table below. For all molecules the spectral overlap is larger for the yellow excitation source. Molecule Excitation Spectral Lifetime (10% bleaching at 0.016 W/cm²

Color overlap excitation) in hours.

Molecule 2 Blue 0.34 73000 (80 °C, uniaxially stretched) (fig- 2E)

Molecule 2 Yellow 0.54 55000 (80 °C, uniaxially stretched)

Molecule 17 Blue 0.05 74000 (80 °C, uniaxially stretched) (fig- 2B)

Molecule 17 Yellow 0.32 9000 (80 °C, uniaxially stretched)

Molecule XI Blue 0.36 27700 (80 °C)

(fig. 21)

Molecule XI Yellow 1Ϊ45 ^* ' 27000 (80 °C)

In Figure 6a the extinction coefficient (in fact excitation spectrum) of the molecule 2 is shown; E_max is at about 560 rim. At about 560 Em maximum excitation intensity is found; in other words: at the specific emission wavelength of which the excitation spectrum is measured, at this excitation wavelength maximum emission signal is found. For instance, at about 430 ran, the value for ε is about a third of e_max, and thus the emission intensity of the monitored emission will be about 1/3 lower tha at excitation wavelength of about 560 nm When irradiated with blue and yellow light sources (of the same power density) having the spectra shown in Figure 6b we found that contrary to the expectations the molecule showed an 1 .33 times longer lifetime under illumination by blue light than yellow light. The lower light sensitivity at blue than at yellow excitation is explained by the lower spectral overlap between blue light and the extinction coefficient spectrum of Molecule 2 (0.34) compared to that with yellow light (0.54).

In Fig. 6c we show the extinction coefficient (in fact excitation spectra) of molecule 17 is shown; e_roax is at about 550 rim. Here as compared to molecule shown above the extinction coefficient per molecule in the blue part is much lower than in the yellow part of the spectrum. As a result the lifetime is a factor of 7 longer when irradiated blue light as compared with irradiation with yellow light.

Figs. 7a/7b schematically depict two configurations. On the left, 7a, a combination of a second luminescent material 120, here a europium doped thiogallate (green), excited with a blue source of light 10, with blue light 11 , and an (first) organic luminescent material 110 (here e.g. molecule 2), excited with (light source light of) the same source of light with blue light. On the right, a structure is chosen wherein the organic luminescent material 110 is also at least partly excited by the luminescence of the thiogallate luminescent material 120. The two different configurations shown in Figs. 7a/7b are configured to create white light on the black body line with a color temperature of 4000K under excitation from blue LED light. The excitation spectra are shown in Fig. 7c, with, EX 1 10 being the excitation of the organic luminescent material and EX 120 being the excitation curve for the second luminescent material 120, here the thiogallate.

After 9000 hr of irradiation by blue light with an intensity of 0.32W/crn2 the left configuration is still white, whereas the right configuration deviates from the BBL, see also fig. 7d: in this figure show the color coordinates are shown for the light sources 7a and 7b before and after illumination with blue light. The round point in the middle shows the staring color point. It can be seen that in configuration 7b, indicated as a triangle point, there is a large shift in the color point. In the case of situation 7a, indicated as a square point, the color point shift only slightly and stays within the 5 SDCM (standard deviation of colour matching) circle.

Claims

CLAIMS:

1. A lighting device (1) comprising (i) a source of light (10) for generating light source light (1 1 ) having a spectral distribution with a maximum intensity at a first wavelength (λΐ) within the visible wavelength range, (ii) a light converter (100) comprising an organic luminescent material, wherein the light converter is transmissive for at least part of the light source light, wherein the organic luminescent material is configured to provide luminescent material light having a wavelength within the visible wavelength range upon excitation with the light source light, wherein the organic luminescent material has an excitation spectrum having a maximum excitation intensity at a second wavelength (λ2), and wherein λ\≠ λ2.

2. The lighting device (1) according to claim 1 , wherein the spectral distribution of the light source light of the source of light and the excitation spectrum of the organic luminescent material have a spectral overlap SO in the range of 0<SO<0.4, wherein the normalized spectral overlap is defined as:

wherein Ι(λ) is the intensity of the light source light of the source of light as a function of wave length, wherein ε(λ) is the extinction coefficient as a function of wavelength based on the excitation spectrum, wherein e_m3K is the maximum extinction coefficient in the

wavelength range of 350-900 mil, based on the excitation spectrum, and wherein λ_χ and _γ define the wavelength range of 350-900 ran.

3, The lighting device (1) according to any one of the preceding claims, wherein the light converter comprises one or more materials selected from the group consisting of PE

(polyethylene), PP (polypropylene), PEN (polyethylene napthalate), PC (polycarbonate), polymethylacrylate (PMA), polymethylmethacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), silicone, polyvinylchloride (PVC), polyethylene terephthalate (PET). (PETG) (glycol modified polyethylenetercphthalate), PDMS

(polydimethylsiloxane), and COC (cyclo olefin copolymer),

4. The lighting device (1) according to claim 3, wherein the light converter comprises pol yethyl eneterephthal te (PET) as material.

5. The lighting device (1) according to any one of the preceding claims, wherein the light converter is arranged remote from the source of light.

6. The lighting device (1) according to any one of the preceding claims, wherein the source of light is a solid state light source such as a light emitting diode (LED) or laser diode.

7. The lighting device (1) according to any one of the preceding claims, further comprising a second luminescent material.

8. The lighting device (1 ) according to claim 7, wherein the second luminescent material is comprised by the light converter.

9. The lighting device (1 ) according to any one of claims 7-8, wherein the second luminescent material comprises a second organic luminescent material.

10. The lighting device (1 ) according to claim 9, wherein the second luminescent material is configured to provide upon excitation with the light source light second

luminescent material light having a wavelength within the visible wavelength range, wherein the second luminescent material has an excitation spectrum having a maximum excitation intensity at a second wavelength (λ3), and wherein λί≠13.

1 1. The lighting device (1) according to any one of claims 9-10, wherein the organic luminescent material is essentially excited by the light source light of the source of light only.

12. The lighting device (1) according to any one of claims 9-11, wherein the organic luminescent material is selected from the group consisting of:

10

Ġ 10

13. The lighting device (1) according to any one of claims 9-12, wherein the organic luminescent material is selected from the group consisting of:

14. The lighting device (1) according to any one of claims 7-13,

wherein the second luminescent material comprises one or more materials selected from the group comprising quantum dots, quantum rods or quantum tetrapods, nano-crystals, a rare earth metal based luminescent material, and an inorganic luminescent material.

15. A lurninaire comprising a lighting device according to any one of the above claims.