Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 SEMICONDUCTOR DEVICES FOR PARTICLE IDENTIFICATION CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present patent application claims priority benefit to U.S. Provisional Patent Application No. 63/544,567, filed on October 17, 2023, the entire content of which is incorporated herein by reference. All references cited anywhere in this specification, including the Background and Detailed Description sections, are incorporated by reference as if each had been individually incorporated. FEDERAL FUNDING [0002] This invention was made with Government support under grant nos. CHE2018176 and 1807292, awarded by the National Science Foundation. The Government has certain rights in the invention. BACKGROUND 1. Technical Field [0003] The currently claimed embodiments of the present invention relate to devices and methods for particle detection and identification, and more particularly to devices and methods for detection and identification of suspended particles by functional groups of the particles. 2. Discussion of Related Art [0004] There are many methods for detecting the presence and concentration of particles in the environment, especially from pollution. There are also methods for collecting particles and analyzing them in offsite laboratories using expensive infrastructure. There are no methods for
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 real time detection and identification of suspended particles by their functional groups. Therefore, there remains a need for improved devices and methods for particle detection and identification. SUMMARY [0005] A device for detection and identification of suspended particles by functional groups of the particles according to an embodiment of the current invention includes a first detector element, a second detector element, and a processor configured to communicate with the first and second detector elements. The first detector element includes a first electrode, a second electrode space apart from the first electrode, and a first organic semiconducting layer extending between and in contact with the first and second electrodes. The second detector element includes a first electrode, a second electrode space apart from the first electrode, and a second organic semiconducting layer extending between and in contact with the first and second electrodes. The first and second organic semiconducting layers differ in at least one of chemical composition or morphology so as to have different electrical responses to different functional groups of particles to be detected, and the processor is configured to indicate a detection and identification of the suspended particles by functional groups of the particles based on the different electrical responses to different functional groups of particles to be detected. BRIEF DESCRIPTION OF THE DRAWINGS [0006] Embodiments of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0007] FIG. 1 is a schematic illustration of a device for detection and identification of suspended particles by functional groups of the particles according to an embodiment of the current invention. [0008] FIGS. 2A-2I show (a) Chemical structure of SCPs. (b) Chemical structure of CCPs. (c) Chemical structure of ACPs. (d) Chemical structure of P3HT. (e) Chemical structure of PDPP4T. (f) Chemical structure of PQT12. (g) Chemical structure of PT-COOH. (h) Schematic image of the carbon particulates exposure method. (i) Schematic image of OFETs measurement setup. [0009] FIGS 3A-3E show: (a) Current ratios change after particle exposure of OFETs with PDPP4T layers. (b) SEM image of 5mg/ml SCPs attached PDPP4T films. (c) SEM image of 5mg/ml CCPs attached PDPP4T films. (d) SEM image of 5mg/ml ACPs attached PDPP4T films. (e) XRD spectra for plain PDPP4T film, 5 mg/ml SCPs attached PDPP4T film, 5 mg/ml CCPs attached PDPP4T film, and 5 mg/ml ACPs attached PDPP4T film. [0010] FIGS. 4A-4F show: (a) Current ratios change after particle exposure of OFETs with P3HT layers. (b) Microscope image of 5 mg/ml CCPs attached P3HT film. (c) SEM image of 5 mg/ml SCPs attached P3HT films. (d) SEM image of 5 mg/ml CCPs attached P3HT films. (e) SEM image of 5 mg/ml ACPs attached P3HT films. (f) XRD spectrums for plain P3HT film, 5 mg/ml SCPs attached P3HT film, 5 mg/ml CCPs attached P3HT film, and 5 mg/ml ACPs attached P3HT film. [0011] FIGS. 5A-5F show: (a) Current ratios change after particle exposure of OFETs with PQT12 layers. (b) SEM image of 5mg/ml SCPs attached PQT12 films. (c) Microscope image of 5 mg/ml SCPs attached PQT12 film (d) SEM image of 5mg/ml CCPs attached PQT12 films. (e) SEM image of 5mg/ml ACPs attached PQT12 films. (f) XRD spectrums for plain PQT12 film, 5 mg/ml SCPs attached PQT12 film, 5 mg/ml CCPs attached PQT12 film, and 5 mg/ml ACPs attached PQT12 film. [0012] FIGS. 6A-6E show: (a) Current ratios change after particle exposure to OFETs with PT-COOH layers, the inset is the current ratios change for SCPs and CCPs attached PT-COOH. (b) SEM image of 5 mg/ml SCPs attached PT-COOH films. (c) SEM image of 5 mg/ml CCPs attached PT-COOH films. (d) SEM image of 5 mg/ml ACPs attached PT-COOH films. (e) XRD
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 spectrums for plain PT-COOH film, 5 mg/ml SCPs attached PT-COOH film, 5 mg/ml CCPs attached PT-COOH film, and 5 mg/ml ACPs attached PT-COOH film. [0013] FIGS. 7A-7C show: (a) Current ratios change after Si-SO3H particle exposure to OFETs with P3HT layers (b) XRD spectrums for plain P3HT film and 5 mg/ml Si-SO3H particles attached-P3HT film. (c) SEM image of 5 mg/ml Si-SO3H particles-attached P3HT films. [0014] FIGS. 8A-8F show: (a) Current ratios change after particle exposure of OFETs with porous PQT12 layers. (b) Current ratios change after particle exposure of OFETs with porous P3HT layers. (c)Microscope image of porous PQT12 film. (d)XRD spectrums for porous PQT12 film, 5 mg/ml SCPs attached porous PQT12 film, 5 mg/ml CCPs attached porous PQT12 film, and 5 mg/ml ACPs attached porous PQT12 film. (e) Microscope image of porous P3HT film (f) XRD spectrums for porous P3HT film, 5 mg/ml SCPs attached porous P3HT film, 5 mg/ml CCPs attached porous P3HT film, and 5 mg/ml ACPs attached porous P3HT film. [0015] FIGS. 9A-9F show: (a) is the laser microscope image of pristine PDPP4T film. (b ) to (f) are laser microscope images of different concentrations of SCPs-treated PDPP4T, from 0.25 mg/mL to 5 mg/mL. [0016] FIGS.10A-10F show: (a) is the laser microscope image of pristine P3HT film. (b) to (f) are laser microscope images of different concentrations of SCPs particles-treated P3HT, from 0.25 mg/mL to 5 mg/mL. [0017] FIGS.11A-11F show: (a) is the laser microscope image of pristine PQT12 film. (b ) to (f) are laser microscope images of different concentration of SCPs-treated PQT12, from 0.25 mg/mL to 5 mg/mL. [0018] FIGS. 12A-12F show: (a) is the laser microscope image of pristine PT-COOH film. (b) to (f) are laser microscope images of different concentrations of SCPs-treated PT-COOH, from 0.25 mg/mL to 5 mg/mL. [0019] FIGS. 13A-13E show: (a) to (e) are laser microscope images of different concentrations of CCPs-treated PDPP4T, from 0.25 mg/mL to 5 mg/mL.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0020] FIGS. 14A-14E show: (a) to (e) are laser microscope images of different concentrations of CCPs-treated P3HT, from 0.25 mg/mL to 5 mg/mL. [0021] FIGS. 15A-15E show: (a) to (e) are laser microscope images of different concentrations of CCPs-treated PQT12, from 0.25 mg/mL to 5 mg/mL. [0022] FIGS. 16A-16E show: (a) to (e) are laser microscope images of different concentrations of CCPs treated PT-COOH, from 0.25 mg/mL to 5 mg/mL. [0023] FIGS. 17A-17E show: (a) to (e) are laser microscope images of different concentration of ACP- treated PDPP4T, from 0.25 mg/mL to 5 mg/mL. [0024] FIGS. 18A-18E show: (a) to (e) are laser microscope images of different concentration of ACPs-treated P3HT, from 0.25 mg/mL to 5 mg/mL. [0025] FIGS. 19A-19E show: (a) to (e) are laser microscope images of different concentration of ACPs-treated PQT12, from 0.25 mg/mL to 5 mg/mL. [0026] FIGS. 20A-20E show: (a) to (e) are laser microscope images of different concentration of ACPs- treated PT-COOH, from 0.25 mg/mL to 5 mg/mL. [0027] FIGS. 21A-21D show: (a) to (d) are laser microscope images of 5 mg/mL concentration SCPs-treated polymer films. The polymers are PDPP4T, P3HT, PQT12, and PTCOOH. [0028] FIGS. 22A-22D show: (a) to (d) are laser microscope 3D images of 5 mg/mL concentration CCPs-treated polymer films. The polymers are PDPP4T, P3HT, PQT12, and PTCOOH. [0029] FIGS. 23A-23D show: (a) to (d) are laser microscope 3D images of 5 mg/mL concentration ACPs-treated polymer films. The polymers are PDPP4T, P3HT, PQT12, and PTCOOH.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0030] FIGS.24A-24F show: (a) is the laser microscope image of porous P3HT film. (b) to (f) are laser microscope images of different concentration of SCPs-treated porous P3HT films, from 0.25 mg/mL to 5 mg/mL. [0031] FIGS. 25A-25F show: (a) is the laser microscope image of pristine porous PQT12 film. (b) to (f) are laser microscope images of different concentration of SCPs-treated porous P3HT films, from 0.25 mg/mL to 5 mg/mL. [0032] FIGS. 26A-26E show: (a) to (e) are laser microscope images of different concentrations of CCPs-treated porous PQT12 films, from 0.25 mg/mL to 5mg/mL. [0033] FIGS. 27A-27E show: (a) to (e) are laser microscope images of different concentrations of CCPs-treated porous P3HT films, from 0.25 mg/mL to 5 mg/mL. [0034] FIGS. 28A-28E show: (a)to (e) are laser microscope images of different concentrations of ACPs-treated porous PQT12 films, from 0.25 mg/mL to 5 mg/mL. [0035] FIGS. 29A-29E show: (a) to (e) are laser microscope images of different concentrations of ACPs-treated porous P3HT films, from 0.25 mg/mL to 5 mg/mL. [0036] FIGS. 30A-30D show: (a) EDS analysis of pure PQT12 film. (b) EDS analysis of porous PQT12 film. (c) EDS analysis of pure P3HT film. (d) EDS analysis of porous P3HT film. [0037] FIGS. 31A-31C show: (a) 13C solid NMR spectrum of SCPs. (b) FT-IR spectrum of SCPs. (c) EDS spectrum of SCPs on PQT12 film. [0038] FIGS.32A-32C show: (a) 13C solid NMR spectrum of CCPs. (b) FT-IR spectrum of CCPs. (c) EDS spectrum of CCPs on PQT12 film. [0039] FIGS.33A-33C show: (a) 13C solid NMR spectrum of ACPs. (b) FT-IR spectrum of ACPs. (c) EDS spectrum of ACPs on PQT12 film. [0040] FIGS.34A-34F show: (a) Transfer curve of PDPP4T-based OFET. (b)Transfer curve of P3HT-based OFET (c) Transfer curve of PQT12-based OFET. (d) Transfer curve of PT-
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 COOH-based OFET. (e) Transfer curve of porous PQT12 OFET. (f) Transfer curve of porous P3HT OFET. [0041] FIGS.35A-35F show: (a) Output curve of PDPP4T-based OFET. (b) Output curve of P3HT-basedOFET (c) Output curve of PQT12-based OFET. (d) Output curve of PT-COOH-based OFET. (e) Output curve of porous PQT12 OFET. (f) Output curve of porous P3HT OFET. [0042] FIGS. 36A-36C show: (a) Experimental and simulative transfer curves of 5 mg/ml SCPs, CCPs, and ACPs-treated P3HT. (b) Experimental and simulative transfer curves of 5 mg/ml SCPs, CCPs, and ACPs-treated PDPP4T. (c) Experimental and simulative transfer curves of 5 mg/ml SCPs, CCPs, and ACPs-treated PQT12. [0043] FIGS.37A-37B show: (a) FT-IR spectrum of Si-SO3H particles. (b) EDS spectrum of Si-SO3H on P3HT film. [0044] FIGS. 38A-38E show: (a) to (f) are laser microscope images of different concentrations of Si-SO3H particles-treated P3HT, from 0.25 mg/mL to 5 mg/mL. DETAILED DESCRIPTION [0045] Some embodiments of the current invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. A person skilled in the relevant art will recognize that other equivalent components can be employed, and other methods developed, without departing from the broad concepts of the present invention. All references cited anywhere in this specification are incorporated by reference as if each had been individually incorporated. [0046] The term “organic semiconducting layer” is intended to have a broad definition to include materials in which the Fermi level for the majority carrier can be modulated to be closer to or farther from the energy at which the carriers are transported. This can also include the case of a good conductor where interaction with the particles might make it a poorer conductor and thus give a signal. That is the case in one of the examples shown below where amino groups are the functional group and holes are the carriers. This also can include the case of a semiconductor
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 with a bandgap, where the modulation causes small increases in the number of carriers at the transport energy, but the original number of carriers at the transport energy is so small that this causes a large increase in conductivity. In the examples below, PQT12 would be a semiconductor with a large bandgap, and PT-COOH is a good conductor (because it is doped by the COOH groups). On the other hand, a true metal such as metallic gold, silver copper, platinum, etc. is not intended to fall within this definition because there are so many carriers at the transport level that they can't be significantly modulated. Furthermore, the organic semiconductor layer can be a layer of small molecules and/or polymers. [0047] The term “layer” can refer to a thin film in some embodiments, but the general concepts of the current invention are not limited to only thin films. [0048] Accordingly, some embodiments of the current invention can provide improved devices and methods for particle detection and identification. In some embodiments, the devices and/or methods can provide detection of particles in real time and provide information about their surface chemistry to help identify their source and possible toxicity. This could inform medical responses to exposures and environmental remediation, for example. In other embodiments, there are many industries where particle monitoring is needed. Although some embodiments can provide devices and methods for real-time detection and/or identification, the broad concepts of the current invention are not limited to only real-time devices and methods. [0049] The term “particle” is intended to have a broad meaning as used herein. A particle can be a solid, a liquid droplet and/or a mixed phase material for example according to some embodiments of the current invention. [0050] The term “real time” is intended to refer to devices and methods that can be used in the field, laboratory, factory, etc. to provide results without having to send a sample off for testing. In some embodiments, “real time” can include substantially continuous monitoring over a period of time. [0051] FIG. 1 is a schematic illustration of a device 100 for detection and identification of suspended particles by functional groups of the particles according to an embodiment of the current invention. The device 100 includes a first detector element 102, a second detector element 104, and a processor 106 configured to communicate with the first and second detector elements
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 (102, 104). The processor 106 can be an electrical and/or electronic circuit, for example. In some embodiments the processor can be or can include one or more computers. The processor 106 is shown very schematically in FIG.1. It can further include a lookup table containing information of responses of the detector elements to types of particles of interest, for example. [0052] FIG. 1 includes a schematic illustration of one possible embodiment of detector elements for clarity. Using this example for illustration, each of the at least two detector elements 102, 104 has at least a first electrode 108, a second electrode 110 space apart from the first electrode 108, and an organic semiconducting layer 112 extending between and in contact with the first and second electrodes (108, 110). In this example, the detector elements are shown with a third electrode 114 with dielectric layer 116 in the form of an organic field effect transiter (OFET). However, the general concepts of the current invention are not limited to only this example. The devices can be two-electrode devices, three electrode devices, or even devices with more than three electrodes. The organic semiconducting layer of the first detector element and the organic semiconducting layer of the second detector element differ in at least one of chemical composition or morphology so as to have different electrical responses to different functional groups of particles to be detected, and the processor is configured to indicate a detection and identification of the suspended particles by functional groups of the particles based on the different electrical responses to different functional groups of particles to be detected. [0053] Some embodiments can include a coating (not shown in FIG.1) of a layer of a material film on the organic semiconducting layer such that particles would still produce an electronic response, but the coating would decrease the adhesion of particles so that gentle air flow or agitation, for example, could dislodge particles so that the sensing device could be reused. A thin (<10 nm) film of low-surface-energy material, such as, but not limited to, a perfluorinated alkyl compound, can be a suitable coating material. [0054] Although FIG. 1 shows an example with two detector elements, the general concepts of the current invention are not limited to only two detector elements. There could be three, four or even more than four detector elements in some embodiments. In addition, each detector element can have two, three, or more than three electrodes. In the three-electrode cases, the detector elements can be in the form of a field effect transistor, for example.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0055] In some embodiments, the second sensing element can be sensitive to a gaseous environment, such as but not limited to the atmosphere, but not to the particles being detected by the first sensing device that is sensitive to both the particles and to the atmosphere, so as to cancel the atmospheric response by the two devices, leaving the response to the particles as the predominant sensing output signal. One way to accomplish this is to have a filter placed in the pathway that delivers the particle-containing atmosphere to the second sensing device. The filter could be in contact with the sensitive material or could otherwise block the approach of particles to the second device but allow gaseous components of the atmosphere to reach the second sensing device. Similar embodiments can include more than two sensing elements, without limitation. [0056] In some embodiments, the particles can include droplets of substantially nonvolatile liquid material in addition to solid material. An example would be a medium chain organic acid, such as what could be generated during cooking, or a partially oxidized molecular fragment of fuel molecules being exhausted from an engine. [0057] The following examples describe embodiments in which carbon particles are functionalized. However, the broad concepts of the current invention are not limited to only functionalized carbon particles and are not limited to the specific functionalization shown as examples. Furthermore, the general concepts are not limited to only the organic semiconductor materials described in the examples. Data is presented below to help describe some concepts of the current invention. [0058] The following describes a new mechanism for particulate matter detection and identification. In the examples, three types of carbon particles were synthesized with different functional groups to mimic the real particulates in atmospheric aerosol. After exposing polymer- based organic field effect transistors (OFETs) to the particle mist, the sensitivity and selectivity of the detection of different types of particles is shown by the current changes extracted from the transfer curves. The results indicate that the sensitivity of the OFETs is related to the structure and functional groups of the organic semiconducting layers, as well as the morphology. The predominant response was simulated by a model that yielded values of charge carrier density increase and charge carriers delivered per unit mass of particles. The research points out that OFETs have the ability to selectively detect particles with multiple functional groups, which reveals an approach for selective detection of particulate matter.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0059] The following examples help illustrate some embodiments of the current invention for detecting carbon particles, which can provide selective detection of particulate matter in aerosols. The sensing mechanisms behind the selectivity and sensitivity, and how to optimize the sensing responses and distinctions are also discussed. The OFETs can be a platform for accurate and efficient particulate detection. 1. Introduction: [0060] Air pollution can be a ubiquitous environmental challenge, and particulate matter (PM) can be a main contributor to air pollution. [1-3] Particulate matter can be defined as a suspension of microscopic particles in the gas phase, which originate from biomass combustion, volcanic eruption, and so on. It will not only degrade human health but also be harmful to the whole ecosystem. [4-9] The sizes of the particulates can range from smaller than 0.1 micrometers to larger than 100 micrometers, and they have diverse constituents including inorganic materials biological compounds, organic carbon, and so forth. [10-12] To largely monitor and control the negative effects of the particulates, multiple types of particulate sensors have been developed.[13] Gravimetric sensors signal the weight of the particulate matter. By weighing the mass discrepancy before and after the particulate matter attachment on the filter in a certain time interval, the concentration of the particulate matter can be estimated. This method has been widely used because of its accuracy, but the drawbacks of this method are its inefficiency and high cost. [13-15] Optical particulate matter sensors are either based on light scattering or 2D matrix cameras. The sensing signal for scattering-based sensors is represented by the light intensity change, while the sensing signal for the camera-based sensors requires an image processing process. The advantages of these types of sensors are the low cost and timely response, but the accuracy of the sensors can be influenced by the environment. [13,16-20] Electrochemical methods have also been used in particulate matter detection. The aerosol can flow through electrochemical cells and the size and concentration of the particulates can be reflected through electrical signal changes. [21-25] [0061] Some embodiments of the current invention provide a new possibility for electrochemical particulate sensors based on organic field effect transistors (OFETs) which do not require electrochemical cells. OFETs are three-terminal devices, with a source, drain, and gate, and also have organic semiconductors (OSCs) as semiconducting layers and a separate insulating layer. [26,27] The π-conjugated structure and the functional groups in the OSCs offer sensitivity to
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 external stimulation and make them a promising platform as sensors.[28-33] The OFET configuration has been used for biosensors, chemical sensors, temperature sensors, gas sensors, and so on. [34-41] We have been previously interested in gas sensors since hazardous gases such as nitrogen dioxide and ammonia are also important components in air pollution. [42,43] It has been shown that the OSCs can interact with the gas molecules during the absorption and desorption process and will transduce the interaction through the OFETs platform. The sensitivity of the OFET sensors can be determined by various factors including the compositions of the OSCs, the means of OSC deposition, the morphology of the OSCs, and so on. [44-49] Although OFET-based gas sensors have been widely studied, to our knowledge, OFET-based particulate matter sensors have not been previously reported. The following examples describe how the OFET platform can provide a detection platform for airborne particulates. [0062] In the following examples, we mainly focus on carbon particulate detection, which could encompass elemental carbon or organic carbon.[51] To approximately mimic the particulate carbon in the atmosphere and have a better understanding of the sensing mechanism, we synthesized three types of carbon particles: hydrogen sulfite functionalized carbon particles (SCPs), carboxylic acid functionalized carbon particles (CCPs) and amine-functionalized carbon particles (ACPs). Illustrative structures of the carbon particles are illustrated in FIGS. 2A-2C. For the semiconducting layers of the OFETs, we chose four contrasting polymers: poly(3- hexylthiophene-2,5-diyl), regioregular (P3HT), Poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4- c]pyrrole-1,4(2H,5H)-dione -3,6-diyl)-alt-(2,2’;5’,2’’;5’’,2’’’-quaterthiophen-5,5’’’-diyl)] (PDPP4T), Poly[bis(3-dodecyl-2-thienyl)-2,2'-dithiophene-5,5'-diyl](PQT12) and poly [3-(4- carboxybutyl)thiophene-2,5-diyl] regioregular(PT-COOH); their structures are shown in FIGS. 2D-2G. [0063] These four types of polymers were used as the OSC layers as well as sensing layers to make the OFET-based particle sensors. The backbones of the polymers comprise diketopyrrolopyrrole (DPP) rings and/or polythiophene chains. These backbones were chosen because some polymers with such backbones have been shown to have hazardous gas sensitivity. [48,49] The sidechains of the four polymers are also not the same, for PDPP4T, P3HT, and PQT12, the side chains were hydrocarbon chains with different lengths, while PT-COOH has carboxylic acid groups in its side chains. The four polymers were chosen also to compare the effect of the side chains: nonpolar, polar, and acidic. The OFETs were exposed to the carbon particulate mist
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 for a certain amount of time, and the current changes extracted from the transfer curves were reported as the sensing signals (details described in the materials and methods section). FIGS.2H and 2I show the exposure and measurement setup. The three types of carbon particulates have different acidities; the SCPs should have the highest acidity and ACPs have the lowest. By attaching the three types of carbon particulates to the four different polymers, we are able to have a better understanding of the interaction mechanisms between the particulates and the OSCs. Besides using different polymers, we also tried to change the morphology of the organic semiconductor layers to make them more porous and followed the same exposure procedure to record the current change. The results indicate a selective detection of the three particles from different polymers, especially at high concentrations, and the change of morphology can affect the sensitivity of the OFET sensors. This is evidence for the OFETs to become more informative particulate matter sensors than those in current use. 2. Results and discussion: 2.1 Results from continuous polymer films incorporated in OFETs responding to carbon-based particles: [0064] Initially, all the carbon-based particles were exposed to OFETs incorporating continuous OSCs for initial observations of interactions between the particles and the OSC layers. FIG. 3A indicates the results for the current ratio change after exposing the PDPP4T-OFETs to the three kinds of particles. Since the particles were dispersed in ethanol, we initially exposed the OFETs to pure ethanol mist as the control experiment. The reason for using ethanol as the solvent for the particles is that ethanol is not destructive to the polymer films and is also easily removed from the sensing system. [0065] The conductivity of the three types of particles was measured with the four-probe method. While ACPs and CCPs showed insulating properties, SCPs have a small conductivity of 1.5*10^ (-5) S/cm. This proves that only particles with the highest acidity can have a small conductivity when compressed together. [0066] In bar plots of responses, the orange-colored bar (left most) represents the result from the control experiment, and the green, purple, and yellow-colored bars (left to right in that order) indicate the current ratio change after the exposure of SCPs, CCPs, and ACPs respectively. ID is
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 the drain-source current extracted from the transfer curve at the maximum gate voltage after the particles’ exposure, and I0 is the initial drain-source current extracted from the transfer curve before the particles’ exposure at the maximum gate voltage. The sensitivity of the OFETs is indicated through the current ratio change. The concentration range was chosen because we want to know the threshold concentration at which the particles start to have obvious effect on the OFETs. [0067] The results show that after ethanol mist exposure, the current ratio has a small increase to 0.4 with a standard deviation of 0.2 for the PDPP4T-incorporated OFETs. The SCPs induce the largest current ratio increase; the average current ratio is about 2 at the lowest concentrations (from 0.25 mg/ml to 1mg/ml), but the highest current ratio change increases further to 4.6 at the highest SCPs concentration of 5mg/ml. While the initial current increases can come from particle bridging of barriers or discontinuities, the additional increase in the current ratio can come from the unique doping by the highly acidic protons of the SCPs above a threshold concentration, up to which protons might be neutralized by basic impurities in the polymer. After the impurities were neutralized and the discontinuities were filled, the doping effect became the dominant effect, so the current was significantly increased. The other two kinds of particles also induced increased the current but did not have such an obvious effect as did the SCPs. For PDPP4T-OFETs treated with CCPs, the obvious current change starts from 1mg/ml concentration, and the maximum current ratio change can reach 2.8. The current increase is smaller with CCPs attachment, again consistent with the importance of doping by the acidic functional groups. Carboxylic acid groups are not as acidic as sulfonate groups, so the proton doping effect is smaller. As for ACPs attached to PDPP4T-OFETs, the increase of the current is even smaller, since ACPs have no proton doping capability. [0068] FIGS. 3B, 3C and 3D are the SEM images of PDPP4T with 5 mg/ml of the different carbon particles on the surfaces, showing evidence of particle aggregation. For films with SCPs on their surfaces, although there are visible aggregates, the distribution of the particles is relatively even. The other two types of particles have more aggregation, which can decrease the effect of doping on total film current. [0069] FIG. 3E is the XRD spectrum of PDPP4T films with 5 mg/ml of the different carbon particles on their surfaces. The effect from the particles was not so obvious on PDPP4T films.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 The intensity of the peak at 15.6 º was only slightly increased after the particles' attachment and was shifted slightly left after CCPs and ACPs attachment. The changes in the peak showed that some particles can land in the PDPP4T films, create microstrain in the crystalline region, and slightly affect the crystallinity. Another possibility is the doping effect from the particles can affect the arrangement of the polymer chains in the crystalline region, which can also change the peaks. But compared with the pure polymer film, the particles overall cause only minimal perturbations of the polymer diffraction peaks. The increase of the current should be related to the doping ability and the concentration of the particles, rather than structural rearrangements. [0070] FIG. 4A shows the results from P3HT-incorporated OFETs after the exposure to the particles. For SCP and CCP-exposed P3HT, the currents start to increase from 2 mg/ml with SCPs showing a slightly larger effect and a maximum average current ratio increase of 1.15, while CCPs attached OFETs have a maximum average current ratio increase of 0.7. This is consistent with the sulfonate groups being stronger dopants than carboxylic acid groups based on their relative acidities. For ACP-exposed P3HT films, the current decreases with the increase of the concentration; the decrease of the current ratio can reach -0.54. This is consistent with amine groups acting as hole traps, related to current decreases associated with p-channel OSCs being exposed to amine vapors.[49] FIGS.4B, 4D and 4E are the SEM images for three types of particles on P3HT films, and FIG.4C is the microscope image of 5mg/ml CCPs on P3HT film. While ACPs show random aggregation on the polymer films, the SCPs, and CCPs formed more dendritic structure on the P3HT films. To further investigate the effect of the dendritic structure, XRD measurements were also done on pure and particle-exposed-P3HT films, and the results are shown in FIG.4F. The intensity and width of the peak at 5.1 º were changed after the application of the particles. The aggregation of the particles (especially the large aggregates) can change the surface morphology and roughness, which can interfere with the X-ray scanning through the polymer films. The intensity of the peaks around 10 º and 15 º was slightly increased, this may be because the particles can be deposited along or close to the grain boundaries, which will squeeze the original atoms in the polymer films and increase the atom density in the same plane. The increase in the number of atoms numbers can lead to the increase of the peak intensity. All in all, the change in XRD spectra is related to the morphology change and atom packing change caused by the particles.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0071] FIG. 5A indicates the results of the PQT12-based OFETs after exposure to the three types of particles. Only after the particle concentration reaches 5 mg/ml, the SCPs can increase the current, while at low concentration range, the SCPs almost have no effect on the OFETs, and the other particles have little effect on the currents. As shown in FIGS. 5B and 5C, the branch- like structure can only form at 5 mg/ml concentration for SCPs, and the structure may be favorable for the doping effect and hole transport. For all the particles, SCPs still have a more even distribution, while ACPs and CCPs can form relatively large aggregates. FIG. 5F presents the results from the XRD. For PQT12 films with SCPs, the peaks at 7.1 º and 13.9 º were slightly increased. This may be because the particles were deposited along or close to the grain boundaries, which can increase the density of the atoms in the crystalline region. The CCPs do not have an obvious effect on the peak at 7.1, but do cause a small increase at the peak at 13.9 º, which also came from the increase in the density of the atoms. The presence of ACPs affects both the intensity of the peaks as well as the position of the peaks. This can relate to the more obvious morphology change and internal stress caused by the ACPs. The change in current can be related to both the doping effect from the functional groups on the particles as well as the change in the crystalline region caused by the penetration of the particles. [0072] FIG. 6A demonstrates the findings from PT-COOH-based devices, which act mostly as resistors rather than OFETs and the insets are re-graphed results from SCP- attached OFETs and CCP-attached OFETs. Here, it is obvious that the ACPs have the largest current-increasing ability, in contrast to expected behavior from p-channel polymers; the current ratio can reach 25 at 5mg/ml! The origin of this ability comes more from proton migration, which was also indicated in our previous publication [49]. The amine groups on the ACPs will have an interaction with the carboxylic acid groups on the polymer side chain, and release free protons that can move in response to voltage. SCP-treated OFETs also show fairly large sensitivity, which may be due to PT-COOH being sensitive to dopants as well as the addition of protons [53]. CCPs show a more modest doping effect, only at the highest concentration used. This is related to the doping ability of the functional groups. The particle distribution is also more uniform for PT-COOH compared to the other polymers, as revealed in FIGS. 6B, 6C, and 6D. The peaks from the original films were not largely affected after the application of the particles. Only 5 mg/ml CCPs-exposed PT- COOH film has a relatively large peak intensity increase and peak shift. This may relate to the arrangement of the CCPs inside the PT-COOH films. Some CCPs may penetrate inside the
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 polymer films, and since the CCPs and PT-COOH both have carboxylic acid groups, the interaction between the CCPs and PT-COOH films can affect the lattice parameter. 2.2 Results from continuous polymer films with Si-based particles: [0073] In order to make sure that the doping effect from the functional groups did not depend on particles being carbon-based, silica-based particles were also synthesized. The Si-SO3H particles were derived from silica gel, and the detailed synthesis process is described in Section 4. The conductivity of the Si-SO3H particles was also measured, which is similar to SCPs, is 1.2 x 10^(-5) S/cm. The Si-SO3H particles were exposed to P3HT-OFETs using the same process as the carbon-based particles. The results are shown in FIG.7A. The tendency of the current change is the same, the difference is the scale of the change. The increase of the current was even higher after the exposure of Si-SO3H particles to P3HT-OFETs, compared with the results from SCPs. The current increase became obvious at 0.5 mg/ml, which is a lower threshold concentration than SCPs, and the maximum increase of the current ratio can reach 4. This can relate to the slightly higher density of the SO3H groups. The atomic ratio among carbon, oxygen, and sulfur atoms of SCPs is 68:28:2, and the atomic ratio among carbon, oxygen, and sulfur atoms of Si-SO3H particles is 66:16:2.5, so the higher density of the SO3H can be one of the reasons for the large increase of the current. Another reason is that the Si-SO3H particles do not have a large aggregation of carbon rings, as shown in FIG. 7C, so the hindrance of charge transport is not so significant. Also, the distribution is more even for Si-SO3H particles. The crystallinity of the P3HT films was not obviously changed, as shown in FIG. 7B. This indicates that the current increase of the Si-SO3H particles attached-P3HT-OFETs should come from the doping effect of the sulfonate groups. 2.3 Results from porous polymer layers: [0074] FIG. 8A demonstrates the results for OFETs which have porous PQT12 as the semiconductor layer. Compared to plain PQT12, the sensitivity for all three kinds of particles has been increased, especially for the SCPs; the highest current ratio change can reach 7.8 at 5mg/ml, and even 2mg/ml SCPs can increase the current ratio change ratio to 2.8. The high sensitivity may come from the formation of the pores; this allows the SCPs to have contact with a larger area of the polymer films and also increases the doping depth of the particles. The roughness and
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 average diameter of the porous PQT12 films were measured through a laser microscope. The average pore size of porous PQT12 is around 830 nm, and the roughness of the porous film is around 0.07µm. Using the measured parameter, the areal ratio between the plain and porous PQT12 film is 1:1.5, which indicates that the area in contact with the particles does increase for porous PQT12 films. For CCPs, the porous PQT12 has a similar trend of increasing the current and decreasing the threshold concentration. As for ACPs, instead of decreasing the current, the APCs attached to porous PQT12 have a slight current-increasing tendency. This could be from a greater “bridging” effect in the porous film compared to a charge-trapping effect. There are also some electron-withdrawn groups like amide or carbonyl groups, which may favor the creation of the holes, so the equilibrium with the hole traps from amine groups, and the electron-withdrawn groups result in the slight increase of the current. As for porous P3HT, although the pore-forming process is the same, the sensitivity only has a subtle increase after SCP attachment compared to plain P3HT, and after CCP attachment, the sensitivity is almost the same. ACP attachment showed little if any effect; the current was not obviously decreased or increased. The difference between the current changing ability may also be related to the depth of particle penetration as well as the arrangement of the side chains. According to the microscope image shown in FIGS. 8C and 8D, the pore size of PQT12 is slightly larger than the pore size of P3HT. Porous P3HT films only have an average pore size of around 460 nm, which is not favorable for the penetration of the larger particles. Also, the introduction of polystyrene into the system may have a different effect on the two polymers; it may be more selectively located on the surface of P3HT. To further understand the effect of polystyrene, we did EDS measurements on plain PQT12, plain P3HT, porous PQT12, and porous P3HT. We did the EDS analysis on different positions, and the selected EDS spectra are shown in FIGS. 30A-30D. The average sulfur weight ratio of plain PQT12 film is 0.33±0.05, and for porous PQT 12 is 0.32±0.04. The average sulfur weight ratio of plain P3HT film is 0.3±0.04, and for porous P3HT film is 0.25±0.07. The weight ratio difference is not large, but the sulfur content of porous P3HT does have a tendency to become smaller, which indicates that the introduction of polystyrene is blocking some parts of the surface of the porous P3HT film. Also, as shown in FIGS. 8D and 8F, FIG. 4F, and FIG. 5F, porous PQT12 does not show an obvious change in crystallinity, but porous P3HT has a relatively strong peak at around 15 º, which means polystyrene may make the polymer film more crystalline, even though its surface may be more insulating. The decrease in the intensity of the peaks after particle
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 treatment is related to the coverage of the particles. Additional peaks between 20 º to 50 º should come from the residual polystyrene.[61-63] 2.3 Response ratios identifying particles: [0075] The average diameters of all three particles (including small and large aggregates) are around 2µm. The atomic ratio among carbon, oxygen, and sulfur atoms of SCPs is 68:28:2, the atomic ratio between carbon and oxygen atoms of CCPs is 57:23, and the atomic ratio among carbon, oxygen, and nitrogen atoms is 47:22:1. The numbers were derived from EDS spectra. [0076] While no single sensing response would conclusively identify particles, the response patterns from the different polymer films are distinct for each kind of particle. Comparing the 5 mg/mL average responses to SCPs relative to the ethanol control, the response ratios are about 10,30, 580, and 300. for PDPP4T, P3HT, PQT12, and PTCOOH. Responses to CCPs were about 6, 18, 68, and 100. Responses to ACPs were 4, -14, 116 and 860. The ACP response was clearly distinguished from the other two by the negative response to P3HT and very high response to PTCOOH. SCPs were distinguished from CCPs by the much higher response by PQT12 to SCPs and significantly higher response by PTCOOH to SCPs compared to CCPs, while the ratio of SCPs to CCPs responses by PDPP4T and P3HT was only about 2. More specifically, the ratios of responses to SCPs by the four polymers were about 1:3:60:30 while responses to CCPs were about 1:3:12:16. Those of ACPs were 1:-4: 30:215. These patterns are clearly different for the three particles. 2.4 Simulation-based effective doping/trap density estimation: [0077] To determine the effective doping or trapping density of the particulate matter, simulation of the transistors was conducted; the response of the transistors as a function of particulate matter was generated using a physical device simulation technique. The methods and equations are described in reference [60]. Device characteristic simulation of transistors was carried out based on the drift-diffusion model using Silvaco’s ‘‘ATLAS’’ device simulator. The device materials are represented by arrays of pixels with relative potentials based on those applied during transfer curve generation, charge densities based on Poisson’s equation and initial device characteristics, transport rates based on densities of states above a transport level, occupancies of those states, and energy-dependent mobilities. Parameters input into the simulative model are
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 shown in Table 1. Current-voltage characteristics of the transistors under particulate matter exposure were generated and matched with experimental data. The experimental and simulative transfer curves are shown in FIGS. 36A-36C. The doping/trap density extracted from the simulation at 5 mg/ml particle concentration is presented in Table 2. All the concentrations except P3HT-ACPs are effective doping concentrations, which are the results of exposure to the corresponding particulate matter. However, when P3HT was exposed to ACPs, the drain current of the transistor decreased, resulting in an effective trap distribution. [0078] Table 1. Mobility and charge transport model parameters (model equation given in ref. [60]) Parameter PDPP4T P3HT PQT12 Band gap 1.3 eV 1.8 eV 2.27 eV Affinity 3.82 eV 3.2 eV 2.97 eV Attempt to jump frequency (ν 0 ) 1 ^10 13 Hz 2 ^10 12 Hz 1 ^10 11 Hz Gamma (γ) 1.16 ^107 cm-1 1.25 ^107 cm-1 1 ^107 cm-1 Beta (β) 1.15 1.5 2.2 Sigma ( ^) 0.24 0.2 0.2 [0079] Table 2. Effective doping for each particulate matter Material Particulate Matter Pure (intrinsic SCPs CCPs ACPs doping) doping doping doping PDPP4T 1.6 ^10 16 cm -3 9 ^10 16 cm -3 5 ^10 16 cm -3 3 ^10 16 cm -3 P3HT 1.2 ^1016 cm-3 2.5 ^1016 cm-3 2.3 ^1016 cm-3 2 ^1014 cm-3 (trap density) PQT12 9 ^10 15 cm -3 3.3 ^10 16 cm -3 1.4 ^10 16 cm -3 1.6 ^10 16 cm -3 [0080] Particles can enhance conductivity of the polymer by either filling the cracks between grain boundaries or passivating existing traps in the polymer [54,55]. This is incorporated in the doping-dependent mobility enhancement model, and the dopant concentrations are predicted by simulation as shown in the table. Particulate matter can also introduce deep carrier traps that reduce charge carrier mobility and suppress the injection of space charges into polymer bulk which results in the accumulation near the electrodes [56]. This is the case for P3HT exposed to ACPs. The traps estimated by the simulation are in the order of 2´1014 cm-3.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0081] For each of the functionalized particles, a mixture of 5 mg particles/ml ethanol was prepared, and 4 ml of the suspension was used, so for every exposure process, we have 20 mg particles in the original suspension. Some of the solids were not dispersed in the suspensions; for SCPs, there were 2.4 mg in the mist, and 0.019 mg on each device. For CCPs, there were 11.3 mg in the mist, and 0.09 mg on each device. For ACPs, there were 19.5 mg in the mist, and 0.15 mg on each device. The area of the bottom of the cage is 270 cm2, and the area of all the devices in total for each exposure is 12.5 cm2, distributed among multiple devices. The volume of polymer in each device is known from the length, width, and thickness of the device films. Thus, the total number of charges induced in each device by the particles per unit film volume is known from Table 2, and the total number of charges for a polymer-particle pair is the number in Table 2 times the polymer film volume. [0082] Because the particles are mostly graphitic carbon, 1 mg of carbon atoms is 8 x 10-5 moles of carbon = 5 x 1019 atoms, so there is one induced charge carrier per every 10-7 to 10-8 carbon atoms. If the thickness of the carbon particles is 5 µm (from the laser optical microscopy), and the layer spacing is 3.3 x 10-4 microns (an accepted value for graphite), then the particles are about 15000 layers thick, so this is one unit of doping per every 1000 surface atoms (30 x 30 atoms square), which is reasonable. 3. Conclusion: [0083] By comparing the sensitivity of the four plain polymer films, PT-COOH has a unique behavior and the highest sensitivity for all the particles, this is because the carboxylic acid groups in the side chains can interact with the amine groups, which allows the formation of free protons to largely increase the current when ACPs were attached. The presence of the functional groups also promotes polymer doping, and this leads to high sensitivity for SCPs and CCPs as well. PDPP4T also has a relatively high sensitivity to all particles, this can come from the different backbones of this polymer. The DPP groups may have more contribution to the sensing of the particles, which leads to a higher current ratio change. As for P3HT and PQT12, these two polymers have similar sensitivity tendencies; the difference in the sensitivity may result from the entry depth of the particles, the morphology of the attached particles, and the sensitivity of the polymers to the electron-withdrawing groups, but for both polymers, SCP attachment led to the largest current increase because of the sulfonate doping ability. The SCPs have the highest doping
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 capability, so it has the highest current increase. The CCPs have a medium doping ability and ACPs have the lowest doping ability, these can be reflected in the change in current. For some polymers, the current change may also be related to the change of the crystallinity of the polymer films. Comparing the plain P3HT, PQT12, and porous P3HT, PQT12, the sensitivity of the particles can be largely increased for porous PQT12 but not for porous P3HT; this is related to the pore size as well as the crystallinity change after adding PS. To draw a conclusion, to obtain a suitable material that can have high sensitivity as well as high selectivity, it is important to design the backbone structure, functional groups in the side chain of the polymers, the pore size of the polymer films, and build on this by considering response patterns among a set of devices need to be considered when developing future particulate sensors. In this work, we have illustrated the ability of the polymer-based OFETs to selectively detect particles, which can stimulate further research in the detection of particulate matter in real atmospheres. 4. Experimental section/Methods: [0084] 4.1 SCPs synthesis: Concentrated Sulfuric acid (100ml, 99%) was added into a 500 ml flask and preheated at 140°C in an oil bath for an hour, and then glycerol (25g) was added dropwise into the preheated sulfuric acid to avoid the violent exothermic reaction. After all the glycerol was added, the reaction was kept at a temperature under 200°C with 1000 rpm stirring speed for another hour. After the reaction the flask was allowed to cool down to room temperature, producing a black precipitate formed in the flask. The black precipitate was washed with distilled water multiple times and enough CaCl2 (much larger than the solubility of CaSO4) was added into the water after the washing process, if there is no more white precipitate forming, the washing process can be considered complete. The black precipitate was dried in a vacuum oven at 80°C for 24 hrs, then ground into powder form. [57]The FT-IR spectrum, 13C solid NMR of SCPs, and EDS analysis of SCPs on PQT12 film are shown in FIGS.31A-31C. [0085] 4.2 CCPs synthesis: 5g citric acid was dissolved in 5 ml distilled water (ultrasonication for 5 mins), then the clear solution was radiated using a microwave with 1000 W for 4 mins. After heating in the microwave, a sticky brown gel-like liquid formed. The liquid was diluted with methanol after t cooling down to room temperature, and then the mixture was heated at 170°C to form a black precipitate. The black precipitate was then ground into powder form.[58]
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 The FT-IR spectrum, 13C solid NMR of CCPs, and EDS analysis of SCPs on PQT12 film are shown in FIGS.32A-32C. [0086] 4.3 ACPs synthesis: 5g citric acid and 5g urea were dissolved in 10 ml distilled water (ultrasonication for 10 mins), then the clear solution was heated by microwave at 1000 W for 5 mins. After the heating process, a black solid formed. The black solid was washed with methanol until after washing the methanol had a light-yellow color. After collecting all the after-wash methanol, the solution was heated at 170°C until a black solid formed. The solid was ground to powder form and stored for future use.[59] The FT-IR spectrum, 13C solid NMR of ACPs, and EDS analysis of SCPs on PQT12 film are shown in FIGS.33A-33C. [0087] 4.4 Si-SO3H particles synthesis: 50 mg silica gel was added to 15 ml acetone in a 100 ml glass beaker. The mixture was stirred until the silica gel was well dispersed in acetone. After the dispersion process, 5 ml of concentrated H2SO4 was slowly added to the system, still with stirring. The slow process is to ensure the dispersion of the sulfuric acid. After the addition of the sulfuric acid, the liquid was kept at room temperature for reaction for at least an hour. After the reaction, a dark red to black liquid is obtained. The liquid was heated at 100 °C and a black precipitate resulted. The black precipitate was washed with distilled water at least 10 times until there was no acid stuck on the surface of the black precipitate. After the washing process, the black precipitate was ground into powder and stored for future use. [0088] 4.5 Particle exposure process: The SCPs, CCPs, and ACPs were added to 4 ml pure ethanol, and ultrasonicated for at least three hours to reach a good dispersion of the particles (the solid may not fully dissolve in ethanol). The concentrations of the particles were 5 mg/ml, 2 mg/ml 1mg/ml, 0.5 mg/ml and 0.25 mg/ml. The turbid liquid was then added to the mist maker. The mist maker was placed in a sealed box with the OFETs, and the devices were exposed to the particle mist for 10 min (until the 4ml liquid was all consumed). After exposure, the devices were heated in the vacuum oven overnight at 60 °C to evaporate ethanol. [0089] 4.6 OFET fabrication process: The OFET devices were fabricated on SiO2-coated silicon wafers. The silicon wafers have a 300 nm SiO2 dielectric layer on top of n++ silicon. For substrate cleaning, the substrates were immersed in isopropanol for 15 min. After drying the substrates with nitrogen blowing, the substrates were merged in piranha solution
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 (VH2O2:VH2SO4=3:7) for at least an hour. After that, the substrates were fully cleaned with distilled water and heated at 150 °C to fully dry. After the drying step, the substrates were placed in UV ozone for 30 min to fully decompose the residual contaminants. 5 mg/ml PDPP4T solution was made by adding solid polymer into chloroform and ultrasonication for at least 2 hours to fully dissolve the polymer, and PQT12 solutions were made by adding the polymers into chlorobenzene, and heating in an oil bath at 60°C for 20 mins until the polymers were fully dissolved; the concentration for P3HT solution was 10 mg/ml, and for PQT1212 mg/ml. PT- COOH was dissolved in DMF in an oil bath at 130 °C for 20 mins, at a concentration of 6 mg/ml. For solutions made for porous films, 12 mg/ml PQT12 was dissolved in 6 mg/ml PS solution in chlorobenzene, while 10 mg/ml P3HT was dissolved in 5 mg/ml PS solution in chlorobenzene with heating in an oil bath for 20 min at 60°C. [0090] For OFET device fabrication, the polymer solutions were spin-coated on the cleaned silicon substrate, at 1600 rpm for 60 s except for PT-COOH solution. PT-COOH solution was spin-coated at 1600 rpm for 320 s. After spin-coating, the samples were put in the vacuum oven overnight at 60 °C to remove the residual solvent. The electrodes were coated on top of the polymer films through thermal evaporation. The electrodes consist of pure gold (50 nm) and were evaporated through a shadow mask (length: 20 µm, width: 1 cm). [0091] 4.7 OFET measurements: These were done following the bottom gate/top contact structure. SiO2 serves as the dielectric layer, and the gate voltage was applied to the silicon underneath. The drain and source electrodes were connected to the drain and source terminals of the semiconductor analyzer, and the gate voltage was applied through the gate terminal of the semiconductor analyzer. The transfer curves were measured before and after the attachment of the particles, with a gate voltage changing from 10 V to -60 V and VDS=-20 V. The transfer curve measurement was repeated at least 5 times to stabilize the measurement system. [0092] 4.8 Conductivity measurement, SEM & XRD: The conductivity measurement was conducted using the four-probe method. The particles were compressed to a tablet with around 150 µm thickness. 10 nA current was applied during the measurement. Before SEM measurement, the samples were coated with 5 nm-thick Pt. The XRD measurements were done with 2 theta range between 4 º to 50 º.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [0093] References: [1] M. Levy Zamora, F. Xiong, D. Gentner, B. Kerkez, J. Kohrman-Glaser, K. Koehler, Environ. Sci. Technol.2019, 53, 838. [2] S. Steinle, S. Reis, C. E. Sabel, Sci. Total Environ 2013, 443, 184. [3] R. Zhang, G. Wang, S. Guo, M. L. Zamora, Q. Ying, Y. Lin, W. Wang, M. Hu, Y. Wang, Chem. Rev.2015, 115, 3803. [4] A. M. Gatti, S. Montanari, Eds., in Case Studies in Nanotoxicology and Particle Toxicology, Academic Press, Boston, 2015, 7–11. [5] P. O. Ukaogo, U. Ewuzie, C. V. Onwuka, in Microorganisms for Sustainable Environment and Health (Eds.: P. Chowdhary, A. Raj, D. Verma, Y. Akhter), Elsevier, 2020, 419–429. [6] I. C. Yadav, N. L. Devi, in Encyclopedia of Environmental Health (Second Edition) (Ed.: J. Nriagu), Elsevier, Oxford, 2019, 386–391. [7] M. Cetin, H. Sevik, K. Isinkaralar, Environmental contaminants 2017, 477. [8] A. Mukherjee, M. Agrawal, Environ Chem Lett 2017, 15, 283. [9] D. A. Grantz, J. H. B. Garner, D. W. Johnson, Environ. Int 2003, 29, 213. [10] W. Crinnion, Integr Med (Encinitas) 2017, 16, 8. [11] B. Acharya, in Biomass Gasification, Pyrolysis and Torrefaction (Third Edition) (Ed.: P. Basu), Academic Press, 2018, 373–391. [12] K.-H. Kim, E. Kabir, S. Kabir, Environ. Int 2015, 74, 136. [13] S. D. Lowther, K. C. Jones, X. Wang, J. D. Whyatt, O. Wild, D. Booker, Environ. Sci. Technol.2019, 53, 11644. [14] I. P. S. Araújo, D. B. Costa, Sustainability 2022, 14, 558. [15] N. Singh, M. Y. Elsayed, M. N. El-Gamal, Sensors 2022, 22, 1727. [16] A. Masic, D. Bibic, B. Pikula, A. Blazevic, J. Huremovic, S. Zero, Atmos. Meas. Tech.2020, 13, 6427. [17] M. Rogulski, A. Badyda, Atmosphere 2020, 11, 1040. [18] J. Kuula, T. Mäkelä, M. Aurela, K. Teinilä, S. Varjonen, Ó. González, H. Timonen, Atmos Meas Tech 2020, 13, 2413. [19] M. Vogt, P. Schneider, N. Castell, P. Hamer, Atmosphere 2021, 12, 961. [20] S. Molaie, P. Lino, Micromachines 2021, 12, 416.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [21] M. I. Mead, O. A. M. Popoola, G. B. Stewart, P. Landshoff, M. Calleja, M. Hayes, J. J. Baldovi, M. W. McLeod, T. F. Hodgson, J. Dicks, A. Lewis, J. Cohen, R. Baron, J. R. Saffell, R. L. Jones, Atmos. Environ.2013, 70, 186. [22] Y.-B. Zhao, J. Tang, T. Cen, G. Qiu, W. He, F. Jiang, R. Yu, C. Ludwig, J. Wang, Sens. Actuators B2022, 351, 130903. [23] H. Yin, H. Wan, A. J. Mason, in 2017 IEEE International Symposium on Circuits and Systems (ISCAS), 2017, 1–4. [24] H. Yin, S. Parsnejad, E. Ashoori, H. Wan, W. Li, A. J. Mason, Microchem. J.2021, 168, 106386. [25] Y. Shen, T. Takeuchi, S. Teranishi, T. Hibino, Sens. Actuators B 2010, 145, 708. [26] Y. H. Lee, M. Jang, M. Y. Lee, O. Y. Kweon, J. H. Oh, Chem 2017, 3, 724. [27] M. Kus, T. Y. Alic, C. Kirbiyik, C. Baslak, K. Kara, D. A. Kara, in Handbook of Nanomaterials for Industrial Applications (Ed.: C. Mustansar Hussain), Elsevier, 2018, 392–429. [28] B. Raj, P. Kaur, P. Kumar, S. S. Gill, Silicon 2022, 14, 4463. [29] S. G. Surya, H. N. Raval, R. Ahmad, P. Sonar, K. N. Salama, V. R. Rao, TrAC, Trends Anal. Chem.2019, 111, 27. [30] Y. Wang, J. Zhang, S. Zhang, J. Huang, Polym. Int. Polymer International 2021, 70, 414. [31] P. W. Sayyad, N. N. Ingle, T. Al-Gahouari, M. M. Mahadik, G. A. Bodkhe, S. M. Shirsat, M. D. Shirsat, Appl. Phys. A 2021, 127, 167. [32] L. Torsi, M. Magliulo, K. Manoli, G. Palazzo, Chem. Soc. Rev.2013, 42, 8612. [33] X. Wu, S. Mao, J. Chen, J. Huang, Adv. Mater 2018, 30, 1705642. [34] P. Lin, F. Yan, Adv. Mater 2012, 24, 34. [35] M. Y. Mulla, P. Seshadri, L. Torsi, K. Manoli, A. Mallardi, N. Ditaranto, M. V. Santacroce, C. D. Franco, G. Scamarcio, M. Magliulo, J. Mater. Chem. B 2015, 3, 5049. [36] T. Minami, T. Sato, T. Minamiki, K. Fukuda, D. Kumaki, S. Tokito, Biosens. Bioelectron.2015, 74, 45. [37] M. Song, J. Seo, H. Kim, Y. Kim, ACS Omega 2017, 2, 4065.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [38] K. Ditte, T. A. Nguyen Le, O. Ditzer, D. I. Sandoval Bojorquez, S. Chae, M. Bachmann, L. Baraban, F. Lissel, ACS Biomater. Sci. Eng.2021, DOI 10.1021/acsbiomaterials.1c00727. [39] S. Mandal, M. Banerjee, S. Roy, A. Mandal, A. Ghosh, B. Satpati, D. K. Goswami, ACS Appl. Mater. Interfaces 2019, 11, 4193. [40] O. Young Kweon, M. Yeol Lee, T. Park, H. Jang, A. Jeong, M.-K. Um, J. Hak Oh, J. Mater. Chem. C 2019, 7, 1525. [41] L. Luo, Z. Liu, VIEW 2022, 3, 20200115. [42] S. Olyaee, A. Naraghi, V. Ahmadi, Optik 2014, 125, 596. [43] A. Saxon, D. Diaz-Sanchez, Nat Immunol 2005, 6, 223. [44] L. Gao, C. Liu, Y. Peng, J. Deng, S. Hou, Y. Cheng, W. Huang, J. Yu, Sens. Actuators B 2022, 368, 132113. [45] S. H. Yu, J. Cho, K. M. Sim, J. U. Ha, D. S. Chung, ACS Appl. Mater. Interfaces 2016, 8, 6570. [46] S. Mun, Y. Park, Y.-E. K. Lee, M. M. Sung, Langmuir 2017, 33, 13554. [47] B. Wang, J. Ding, T. Zhu, W. Huang, Z. Cui, J. Chen, L. Huang, L. Chi, Nanoscale 2016, 8, 3954. [48] T. Mukhopadhyaya, J. S. Wagner, H. Fan, H. E. Katz, ACS Appl. Mater. Interfaces 2020, 12, 21974. [49] J. Wagner, Y. Song, J. Shapiro, H. E. Katz, J. Mater. Chem. C 2022, 10, 2149. [50] J. Rivnay, S. Inal, A. Salleo, R. M. Owens, M. Berggren, G. G. Malliaras, Nat Rev Mater 2018, 3, 1. [51] A. M. Jones, R. M. Harrison, Atmos. Environ.2005, 39, 7114. [52] K. Müllen, W. Pisula, J. Am. Chem. Soc.2015, 137, 9503. [53] H.-J. Jang, Y. Song, J. Wagner, H. E. Katz, ACS Appl. Mater. Interfaces 2020, 12, 45036. [54] S. D. S, M. Vandana, S. Veeresh, H. Ganesh, Y. S. Nagaraju, H. Vijeth, M. Basappa, H. Devendrappa, IOP Conf. Ser.: Mater. Sci. Eng.2022, 1221, 012060. [55] M. Nikolka, K. Broch, J. Armitage, D. Hanifi, P. J. Nowack, D. Venkateshvaran, A. Sadhanala, J. Saska, M. Mascal, S.-H. Jung, J.-K. Lee, I. McCulloch, A. Salleo, H. Sirringhaus, Nat. Commun.2019, 10, 2122. [56] Z. Li, B. Du, C. Han, H. Xu, Sci. Rep.2017, 7, 4015.
Venable Ref.: 2240-598825 JHU Ref.: C18011_ P18011-03 [57] D. Lee, Molecules 2013, 18, 8168. [58] N. Dhenadhayalan, K.-C. Lin, R. Suresh, P. Ramamurthy, J. Phys. Chem. C 2016, 120, 1252. [59] R. Tabaraki, O. Abdi, J. Fluoresc.2019, 29, 751. [60] W. Wondmagegn, Y. Chu, H. Li, H. E. Katz, J. Huang, J. Comput. Electron.2021, 20, 626. [61] L. Shang, X. Li, Y. Wang, e-Polymers 2013, 13, DOI 10.1515/epoly-2013-0108. [62] V. Chavan, J. Anandraj, G. M. Joshi, M. T. Cuberes, J Mater Sci: Mater Electron 2017, 28, 16415. [63] G. Huang, J. Xu, P. Geng, J. Li, Minerals 2020, 10, 452. [0094] While various embodiments of the present invention have been described above, they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described illustrative embodiments but should instead be defined only in accordance with the following claims and their equivalents. [0095] The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art how to make and use the invention. In describing embodiments of the disclosure, specific terminology is employed for the sake of clarity. However, the disclosure is not intended to be limited to the specific terminology so selected. The above-described embodiments of the disclosure may be modified or varied, without departing from the invention, as appreciated by those skilled in the art considering the above insights. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.