CN109037398A - A kind of preparation method of caesium tin iodine film and photovoltaic device based on it - Google Patents

Abstract

The invention discloses a preparation method of a cesium tin iodine thin film and a photovoltaic device based on the same. The thin film is obtained by preparing _Cs2SnI6 powder from _SnI4 and _CsAc as raw materials, and depositing it on a target substrate through a spraying process. The obtained Cs ₂ SnI ₆ thin film of the present invention is uniform and dense, and it is used as a light-absorbing layer to make photovoltaic devices. The process is simple, pollution-free, and the raw materials are abundant and cheap. Development and application of mining solar cells.

Description

A kind of preparation method of cesium tin iodine film and photovoltaic device based on it

technical field

The invention relates to a preparation method of a Cs ₂ SnI ₆ thin film and a photovoltaic device based thereon, and belongs to the field of preparation technology of thin film solar battery photovoltaic devices.

Background technique

Perovskite cell is a new type of solar cell with perovskite thin film material as the light absorption layer, generally expressed as AMX ₃ , where A represents a cation, commonly methylamine (MA), methylamine (FA) and cesium (Cs) Wait. In recent years, organic-inorganic hybrid perovskite solar cells have attracted widespread attention in the photovoltaic industry due to their excellent photoelectric properties, but they are facing a serious problem, that is, poor thermal stability, which makes them unusable. in actual production. The poor thermal stability of organic-inorganic hybrid perovskite solar cells is mainly caused by the fact that organic groups are easily decomposed by heat and absorb moisture in the air. Therefore, replacing organic groups with more stable inorganic ions Cs is expected to solve the problem of perovskite solar cells. The stability of mining batteries.

In recent years, the new inorganic perovskite material CsMX ₃ (M=Pb, Sn; X=I, Br) has attracted extensive attention of researchers due to its excellent photoelectric performance and good thermal stability, and is expected to solve the problem of traditional organic calcium The stability bottleneck of titanium battery. The Cs ₂ SnI ₆ in the cubic phase is the oxidation state of the CsSnI ₃ perovskite structure. Since the divalent Sn of the CsSnI ₃ perovskite material is easily oxidized to tetravalent Sn in the air, it cannot be exposed to the air, which limits the use of this material. further application. However, Cs ₂ SnI ₆ material has higher carrier concentration and mobility, and can exist stably in air. Moreover, compared with traditional Pb perovskite materials, Sn materials have the advantages of non-toxicity, environmental protection, pollution-free, and cheap price. Therefore, it is particularly important to develop the preparation technology of Cs ₂ SnI ₆ thin film materials with low cost, simple process and good stability.

The traditional synthesis method of Cs ₂ SnI ₆ is a complex high-temperature synthesis method. In an argon atmosphere, HI, H ₃ PO ₂ and SnI ₂ are added to a three-necked flask, and HSnI ₃ is first synthesized in an oil bath at 120°C, and then Add CsI to form a yellow crystal, dissolve it with acetone, place it in an argon atmosphere for 20-24 hours to obtain Cs ₂ SnI ₆ , and finally wash and filter with absolute ethanol to obtain a usable Cs ₂ SnI ₆ powder sample. This method is complex and time-consuming, and requires high technology.

Contents of the invention

In order to avoid the disadvantages of the above-mentioned prior art, the invention discloses a preparation method of a cesium tin iodide thin film and a photovoltaic device based on it.

The present invention adopts following technical scheme for realizing the purpose of the invention:

The invention firstly discloses a preparation method of cesium tin iodine thin film, which is characterized in that: firstly dissolving SnI ₄ and CsAc in ethanol, stirring continuously, the obtained reaction solution is centrifuged and vacuum dried to obtain Cs ₂ SnI ₆ powder; Then the Cs ₂ SnI ₆ powder is dissolved in a DMF solution, and deposited on the target substrate through a spraying process, that is, a Cs ₂ SnI ₆ film is obtained. Specifically include the following steps:

(1) Dissolve 1mmol CsAc in 1-5mL of absolute ethanol, add 1mmol of _SnI4 powder, continue to stir for 1-3h, centrifuge the reaction solution, and dry the black precipitate at 60°C for 4-8h in vacuum to obtain Cs ₂ SnI ₆ powder;

(2) Dissolving the Cs ₂ SnI ₆ powder in DMF and stirring at room temperature for 2 h to obtain a 250 mg/mL Cs ₂ SnI ₆ solution;

(3) Preheat the target substrate to 120-140°C, add the Cs ₂ SnI ₆ solution into the spray gun, and then spray evenly on the target substrate for 20 seconds to form a uniform and dense film, and finally anneal at constant temperature for 5-15 minutes , That is Cs ₂ SnI ₆ film.

The present invention also discloses a photovoltaic device based on cesium tin-iodide thin film, as shown in Figure 1, it is sequentially deposited on the surface of FTO conductive glass with a dense layer TiO ₂ as an electron transport layer and Cs ₂ SnI ₆ as a light absorption layer Thin film, Sprio-OMeTAD thin film (HTM) as hole transport layer, and positive and negative electrodes (Ag).

The preparation method of above-mentioned photovoltaic device, comprises the steps:

(1) In order to prevent the short circuit of the battery caused by the pinching of the film when testing the battery, the surface of the FTO conductive glass is partially etched, specifically: the surface of the FTO conductive glass is divided into a deposition area and a non-deposition area, and the local uniformity in the deposition area Spread zinc powder on the surface, then drop 2M HCl on the zinc powder and etch for 5 minutes;

Clean and dry the etched FTO conductive glass (clean the etched FTO conductive glass sequentially with soapy water, acetone, and ethanol for 20 minutes, then blow dry with _N2 , and then use a UV-ozone cleaning machine to clean for 20 minutes) , get clean FTO conductive glass.

( ₂ ) Deposit dense layer TiO in the deposition area of FTO conductive glass surface as electron transport layer;

(3) Forming a Cs ₂ SnI ₆ thin film on the electron transport layer by the above-mentioned preparation method as the light absorption layer;

(4) Preparing a Sprio-OMeTAD thin film on the Cs ₂ SnI ₆ thin film as a hole transport layer.

(5) vapor-deposit Ag electrode on the non-deposition area of described FTO conductive glass surface as negative electrode, vapor-deposit Ag electrode on described hole transport layer as positive electrode, negative electrode and electron transport layer, light-absorbing layer and spacer The hole transport layer is not in contact, and a perovskite photovoltaic device based on the Cs ₂ SnI ₆ thin film is obtained.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The preparation method of the Cs ₂ SnI ₆ thin film of the present invention has simple process, no pollution, abundant and cheap raw materials, and is especially suitable for the preparation of large-volume, low-cost solar cells, which is conducive to promoting the development and application of inorganic perovskite solar cells.

2. The Cs ₂ SnI ₆ thin film prepared by the present invention is uniform and dense, stable and difficult to phase change when exposed to air.

3. The present invention adopts the Cs ₂ SnI ₆ deformed perovskite structure as the light-absorbing layer material to prepare perovskite solar thin film cells. Compared with commonly used organic-inorganic hybrid perovskite solar cells, it can effectively avoid the current solar cell preparation. The tedious glove box operation and the investment of expensive vacuum evaporation equipment can realize the low-cost preparation of high-quality and stable perovskite light-absorbing layer films in ordinary atmospheric environments.

4. Compared with the traditional Pb perovskite material, the Cs ₂ SnI ₆ thin film material of the present invention has the advantages of non-toxicity, environmental protection, pollution-free, and cheap price, and is more suitable for use as solar cells for outdoor applications, and is more conducive to industrialization promote.

Description of drawings

Fig. 1 is the structural representation of the perovskite solar cell based on cesium tin iodine film;

Fig. 2 is the schematic diagram of the spraying method of Cs ₂ SnI ₆ film;

Fig. 3 is the X-ray diffraction (XRD) pattern of _Cs2SnI6 thin film in embodiment ₁ ;

Fig. 4 is the scanning electron micrograph (SEM) of Cs ₂ SnI ₆ thin films in embodiment 1;

Fig. 5 is the current density-voltage (JV) characteristic curve of the perovskite solar cell based on Cs ₂ SnI ₆ thin films in embodiment 1;

Fig. 6 is the current density-voltage (JV) characteristic curve of the perovskite solar cell based on Cs ₂ SnI ₆ thin films in embodiment 2;

7 is the current density-voltage (JV) characteristic curve of the perovskite solar cell based on the Cs ₂ SnI ₆ thin film in Example 3. FIG.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and comprehensible, specific implementations of the present invention will be described in detail below in conjunction with examples. The following content is only an example and description of the concept of the present invention. Those skilled in the art make various modifications or supplements to the described specific embodiments or replace them in similar ways, as long as they do not deviate from the concept of the invention Or beyond the scope defined in the claims, all should belong to the protection scope of the present invention.

Example 1

In this example, a Cs ₂ SnI ₆ thin film and a solar cell based on it are prepared according to the following steps:

(1) Dissolve 1 mmol of CsAc in 2 mL of absolute ethanol, then add 1 mmol of SnI ₄ powder, continue to stir for 2 hours, centrifuge the reaction solution, and dry the black precipitate at 60°C for 6 hours in vacuum to obtain black Cs ₂ SnI ₆ powder;

(2) Cut the FTO conductive glass into a small piece of 20×15mm, and divide it into two parts with a width of 15mm and a width of 5mm, which are respectively used as a deposition area and a non-deposition area. Then the 5 mm width of the deposition area away from the non-deposition area was used as an etching area. Stick the tape on the part of the non-etched area, and leak out the etched area. Spread zinc powder evenly on the etching area, drop 2M HCl solution on the laid zinc powder, and etch for 5 minutes.

The etched FTO conductive glass was ultrasonically cleaned with soapy water, acetone, and ethanol for 20 minutes, then dried with _N2 , and then cleaned with a UV-ozone cleaner for 20 minutes to obtain a clean FTO conductive glass.

(3) Deposit dense layer _TiO in the deposition area on the FTO conductive glass surface as electron transport layer: first get 1g75% two (acetylacetonate) diisopropyl titanate isopropanol solution (wt %) and add to 10.3g Form a 0.15mol/L TiO ₂ precursor solution in n-butanol, take 2-3 drops of the above solution and add it dropwise to the non-etching area of the clean FTO conductive glass surface, spin coat at 2000rpm for 40s, remove the substrate, and dry at 135°C for 10min , and then sintered at 500°C for 30min; after sintering, the substrate was treated with 40mmol/L TiCl ₄ aqueous solution at 70°C for 30min, and then sintered at 500°C for 30min to obtain a dense layer of TiO ₂ (FTO/c-TiO2).

(3) Dissolve Cs ₂ SnI ₆ powder in DMF, stir at room temperature for 2 h to obtain 250 mg/mL Cs ₂ SnI ₆ solution;

Preheat the FTO/c-TiO ₂ substrate obtained in step (2) to 130°C, add the Cs ₂ SnI ₆ solution into the spray gun, and then spray evenly on the substrate for 20s to form a uniform and dense film. Cs ₂ SnI ₆ thin film was obtained by annealing at ℃ for 10 min.

(4) Prepare Sprio-OMeTAD film on Cs ₂ SnI ₆ film as hole transport layer: take 72.3 mg of 2,2',7,7',-[N,N-bis(4-methoxyphenyl)amino ]-9,9'-spirobifluorene was dissolved in 1 mL of chlorobenzene, and 17.5 μL of 0.52 g/mL lithium bistrifluoromethanesulfonimide in acetonitrile and 28.8 μL of 4-tert-butylpyridine were added, The Sprio-OMeTAD thin film spin-coating liquid was obtained; the Sprio-OMeTAD spin-coating liquid was spin-coated on the Cs ₂ SnI ₆ thin film at a spin-coating speed of 4000 rpm and a spin-coating time of 30 s to obtain a hole transport layer.

(5) Evaporate an Ag electrode on the non _- deposition area of the FTO conductive glass surface as the negative electrode, and vapor-deposit the Ag electrode _on the hole transport layer as the positive electrode. Perovskite photovoltaic devices.

Fig. 1 is the structural representation of the perovskite solar cell based on cesium tin iodine thin film; Fig. ₂ is Cs ₂ SnI The schematic diagram of thin film spraying method _; Fig. ₃ is the X-ray diffraction ( XRD) figure; FIG. 4 is a scanning electron micrograph of the Cs ₂ SnI ₆ thin film prepared in this embodiment. It can be seen that the film obtained in this example is uniform and dense.

Perform a performance test on the perovskite photovoltaic device produced in this example: the test temperature is 25°C; the relative humidity is 30%; the spectral irradiance of the light source is 100mW/m ² , and has a standard AM1.5 solar spectral irradiance degree distribution. After testing, the current density-voltage (JV) characteristic curve of the battery is shown in FIG. 5 .

Example 2

In this embodiment, the Cs ₂ SnI ₆ thin film and the solar cell based on it are fabricated according to the same method as in the embodiment 1, except that the annealing temperature in step (3) is 120° C. After testing, the film produced in this embodiment is uniform and dense, and the JV characteristic curve of the corresponding solar cell is shown in FIG. 6 .

Example 3

In this embodiment, the Cs ₂ SnI ₆ thin film and the solar cell based on it are fabricated by the same method as in the embodiment 1, except that the annealing temperature in step (3) is 140° C. After testing, the film produced in this embodiment is uniform and dense, and the JV characteristic curve of the corresponding solar cell is shown in FIG. 7 .

The above are only exemplary embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention Inside.

Claims (4)

1. a kind of preparation method of cesium tin iodine thin film is characterized in that: at first SnI ₄ and CsAc are dissolved in ethanol, keep stirring, gained reaction solution is through centrifugation, vacuum drying, obtains Cs ₂ SnI ₆ powder; The above Cs ₂ SnI ₆ powder is dissolved in a DMF solution, and deposited on a target substrate by a spraying process to obtain a Cs ₂ SnI ₆ thin film. 2. preparation method according to claim 1, is characterized in that, specifically comprises the steps: (1) Dissolve 1mmol CsAc in 1-5mL of absolute ethanol, add 1mmol of _SnI4 powder, continue to stir for 1-3h, centrifuge the reaction solution, and dry the black precipitate at 60°C for 4-8h in vacuum to obtain Cs ₂ SnI ₆ powder; (2) Dissolving the Cs ₂ SnI ₆ powder in DMF and stirring at room temperature for 2 h to obtain a 250 mg/mL Cs ₂ SnI ₆ solution; (3) Preheat the target substrate to 120-140°C, add the Cs ₂ SnI ₆ solution into the spray gun, and then spray evenly on the target substrate for 20 seconds to form a uniform and dense film, and finally anneal at constant temperature for 5-15 minutes , That is Cs ₂ SnI ₆ film. 3. a photovoltaic device based on cesium tin iodine thin film, it is characterized in that: described photovoltaic device is deposited with the dense layer TiO ₂ as electron transport layer successively on FTO conductive glass surface, as light absorbing layer with claim 1～ The Cs ₂ SnI ₆ film prepared by any one of the preparation methods in 2, the Sprio-OMeTAD film as the hole transport layer, and the positive and negative electrodes. 4. a preparation method of the photovoltaic device described in claim 3, is characterized in that, comprises the steps: (1) The surface of the FTO conductive glass is divided into a deposition area and a non-deposition area, and zinc powder is evenly spread on the local area of the deposition area, then 2M HCl is dripped on the zinc powder, and etched for 5min; FTO conductive glass cleaning and drying; ( ₂ ) Deposit dense layer TiO in the deposition area of FTO conductive glass surface as electron transport layer; (3) forming a Cs ₂ SnI ₆ thin film on the electron transport layer with the preparation method described in any one of claim 1 or 2, as the light absorbing layer; (4) preparing a Sprio-OMeTAD film on the Cs ₂ SnI ₆ film as a hole transport layer; (5) Evaporate an Ag electrode on the non-deposition area on the surface of the FTO conductive glass as a negative electrode, and vapor-deposit an Ag electrode on the hole transport layer as a positive electrode to obtain a perovskite based on Cs ₂ SnI ₆ thin films Photovoltaic devices.