CN103426971A - Sol-gel preparation method of copper-zinc-tin-sulfur solar cell film - Google Patents

Abstract

The invention discloses a sol-gel preparation method of a copper-zinc-tin-sulfur solar cell film, comprising: step 1, respectively dissolving compounds containing copper, zinc, tin and sulfur in a solvent to prepare a stable copper-zinc-tin Sulfur precursor sol; step 2, coating the prepared copper-zinc-tin-sulfur precursor sol on the substrate, and heat-treating to obtain a copper-zinc-tin-sulfur solar cell absorber film. The method of the invention has low requirements on equipment, simple operation, low preparation cost, and easy adjustment of components; the use of non-toxic or low-toxic solvents is beneficial to environmental protection and the safety of workers; the method does not need to go through a vulcanization process, and avoids pollution in the production process .

Description

Sol-gel preparation method of copper-zinc-tin-sulfur solar cell thin film

technical field

The invention relates to the technical field of photoelectric functional materials, in particular to a method for preparing a copper-zinc-tin-sulfur solar battery thin film.

Background technique

In recent years, the issue of energy and environmental maintenance has been paid more and more attention and attention by people, thus promoting the development of solar cells, and solar cells will become an important alternative energy source in the future.

Copper-zinc-tin-sulfur quaternary compound has kesterite structure, its bandgap is 1.2-1.6eV, which is very close to the optimum bandgap required by semiconductor solar cells, and its absorption coefficient is as high as 10 ⁴ cm ^-1 . The elements contained in the copper-zinc-tin-sulfur compound are very abundant on the earth, and do not contain toxic components, and are environmentally friendly. The mainstream product of the battery.

At present, the highest photoelectric conversion efficiency of copper-zinc-tin-sulfur thin film solar cell has reached 8.4% (B.Shin, O.Gunawan, Y.Zhu, NA Bojarczuk, SJChey and S.Guha. Thin film solar cell with 8.4% power conversion efficiency using an earth-abundant Cu ₂ ZnSnS ₄ absorber.Prog.Photovolt.: Res.Appl.2011, DOI: 10.1002/pip.1174); the highest photoelectric conversion efficiency of copper-zinc-tin-sulfur-selenium thin-film solar cells has reached 11.1% (TKTodorov, J.Tang, S.Bag, O.Gunawan, T.Gokmen, Y.Zhu and DBMitzi.Beyond11%efficiency:characteristics of state-of-the-art Cu ₂ ZnSn(S,Se) ₄ solar cells.Adv.Energy Mater., 2012, DOI: 10.1002/aenm.201200348), reaching or approaching the efficiency of commercial amorphous silicon thin-film solar cells, but this is far from the theoretical photoelectric conversion efficiency of 32%, and it is necessary to continuously improve and develop CZTS ( Copper zinc tin sulfur) thin film and battery component preparation technology.

At present, the methods for preparing copper-zinc-tin-sulfur compounds mainly include vacuum method and non-vacuum method. Among them, the vacuum method has high requirements for equipment, complicated operation and high preparation cost, while the non-vacuum method is simple to operate and easy to adjust the components. At present, most of the vacuum method and the non-vacuum method require subsequent vulcanization (sulfurization: heat treatment in an atmosphere containing sulfur or hydrogen sulfide), especially the non-vacuum method requires vulcanization treatment, so there is an environmental pollution problem.

The invention proposes a new preparation method of copper-zinc-tin-sulfur photoelectric material, which does not need a vulcanization process and avoids pollution in the production process, and the method has low requirements on equipment and can further reduce production costs.

Contents of the invention

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a sol-gel preparation method of a copper-zinc-tin-sulfur solar cell absorbing layer film, the solvent of which is a mixture of non-toxic or low-toxic organic matter and water, and the method can effectively Reduce the cost of preparing solar cell absorber layer.

The sol-gel preparation method of the copper-zinc-tin-sulfur solar cell film of the present invention comprises the following:

Step 1, respectively dissolving compounds containing copper, zinc, tin, and sulfur in an organic solvent or a mixed solvent of an organic solvent and water to make a stable copper-zinc-tin-sulfur precursor sol; specifically, the solvent can be alcohol or A mixed solvent of water and alcohol.

Step 2, coating the prepared copper-zinc-tin-sulfur precursor sol on the substrate, and heat-treating it to obtain a copper-zinc-tin-sulfur solar cell absorber film.

Among them, the "sol-gel method" refers to the use of compounds containing highly chemically active components as precursors, uniform mixing of these raw materials in the liquid phase, and chemical reactions of hydrolysis and condensation to form a stable transparent solution in the solution. In the sol system, the sol slowly polymerizes between the aging colloidal particles to form a gel with a three-dimensional space network structure, and the gel network is filled with solvents that have lost fluidity to form a gel. The gel is dried, sintered and solidified to prepare molecular and even nano-substructure materials.

In step 1, the compound containing copper is any one of copper nitrate, copper chloride, and copper sulfate, and the compound containing zinc is any one of zinc nitrate, zinc chloride, and zinc sulfate. The tin-containing compound is any one of stannous chloride, stannous sulfate, and tin tetrachloride, and the sulfur-containing compound is thiourea.

In step 1, the molar ratio of the copper, zinc, tin and sulfur compounds is 2:(1-1.5):(1-1.5):(4-12).

In step 1, the solvent is any one or any combination of ethanol, methanol, ethylene glycol, isopropanol, glycerol, or ethanol, methanol, ethylene glycol, isopropanol, glycerin Any one or more alcohols mixed with water. Wherein, the molar ratio of water to alcohol is (0-2):1.

In step 1, the preparation temperature of the copper-zinc-tin-sulfur precursor sol is 25-180°C.

In step 2, the coating is spin coating, dip coating, inkjet printing or screen printing. Wherein, the rotational speed of spin coating is 500-6000 rpm for 10-50 seconds.

In step 2, the substrate is a glass substrate, a molybdenum sputtered glass substrate or a polyimide flexible substrate.

In step 2, the heat treatment method is pre-annealing at 100-350° C. for 0.5-60 minutes in air, and then annealing at 300-600° C. for 2-90 minutes in an inert atmosphere (N ₂ , Ar).

The beneficial effects of the present invention are that the method has low requirements on equipment, simple operation, low preparation cost, easy adjustment of the ratio of the four components (compounds containing copper, zinc, tin, sulfur), and is conducive to the preparation of high-efficiency copper The absorbing layer material required for zinc-tin-sulfur solar cells; the solvents used are non-toxic or low-toxic, which is beneficial to environmental protection and the safety of the staff; Low requirements can further reduce production costs.

Description of drawings

Fig. 1 is the XRD phase analysis diagram of the copper-zinc-tin-sulfur solar cell thin film prepared in embodiment 1;

Fig. 2 is the Raman diagram of the copper-zinc-tin-sulfur solar cell thin film prepared in embodiment 1;

Fig. 3 is the SEM figure of the copper-zinc-tin-sulfur solar cell thin film prepared in embodiment 1;

FIG. 4 is an XRD phase analysis diagram of the copper-zinc-tin-sulfur solar cell thin film prepared in Example 2. FIG.

Detailed ways

The present invention will be further described in detail in conjunction with the following specific embodiments and accompanying drawings. The process, conditions, reagents, experimental methods, etc. for implementing the present invention are general knowledge and common knowledge in the art except for the content specifically mentioned below, and the present invention has no special limitation content.

Example 1:

Weigh 1.9398g Cu(NO ₃ ) ₂ 3H ₂ O, 1.4303g Zn(NO ₃ ) ₂ 6H ₂ O, 1.0381g SnCl ₂ 2H ₂ O, 2.4453g thiourea (the molar ratio is about 2:1.3 : 1.2: 8), then added to the mixed solution of 10ml ethanol and water (V _water /V _alcohol = 1: 3), stirred continuously at room temperature for about 2h to form a light yellow sol, and obtain the copper zinc tin sulfur precursor sol. In this method, the order of adding the compounds containing copper, zinc, tin and sulfur is not particularly limited. The prepared CuZnSnS precursor sol was spin-coated on a glass slide at a speed of 2000 rpm for 20 seconds; the CuZnSnS precursor film was pre-annealed in air at 250 °C for 5 min, and then _N2 atmosphere Annealing at 550°C for 10 minutes, and cooling to obtain a thin film of the absorbing layer of a copper-zinc-tin-sulfur solar cell.

According to Table 1, it can be seen that the chemical composition of the CZTS thin film prepared in Example 1 basically conforms to the stoichiometric ratio.

The chemical composition of the CZTS film prepared in Table 1 Example 1

Figure 1 is the XRD pattern of the prepared CZTS film. It can be seen from Figure 1 that the XRD of the sample has diffraction peaks at 18.2°, 28.5°, 33.0°, 38.0°, 47.5° and 56.3° at 2θ, corresponding to (101), (112), (200), (211), (220) and (312) diffraction indexes in the standard spectrum card JCPDF26-0575 (Kesterite Phase Copper-Zinc-Sn-Sulfur Compounds). In addition, no other impurity phase peaks are found in Figure 1, indicating that there is no impurity phase in the prepared CZTS film. Figure 2 is the Raman diagram of the prepared CZTS thin film. It is found that there are three obvious peaks at 286, 331, and 664 cm ^-1 respectively. These three Raman peaks are all peaks of the CZTS thin film. Fig. 3 is the SEM detection result of the prepared CZTS thin film. It can be seen from the SEM image that the surface of the CZTS thin film is flat and dense without cracks, and the average particle size is about 150nm. The experimental results show that, in this example, a copper-zinc-tin-sulfur thin film with a kesterite structure was prepared.

Example 2:

Weigh 2.0061g CuSO ₄ ·5H ₂ O, 1.5152g ZnSO ₄ ·7H ₂ O, 1.0984g SnCl ₂ ·2H ₂ O, 2.4437g thiourea (the molar ratio is about 2:1.3:1.2:8), and then Add it into 10ml of ethanol, and stir continuously at room temperature for about 2 hours to form a light yellow sol, and obtain a copper-zinc-tin-sulfur precursor sol. The prepared CuZnSnS precursor sol was spin-coated on a glass slide at a speed of 2000 rpm for 20 seconds; the CuZnSnS precursor film was pre-annealed in air at 300 °C for 5 min, and then _N2 atmosphere Annealing at 500°C for 10 minutes, and cooling to obtain a thin film of the absorbing layer of a copper-zinc-tin-sulfur solar cell.

As shown in Figure 4, the XRD of the sample has diffraction peaks at 28.5°, 33.0°, 47.5° and 56.3°, which correspond to (112) and (200) of kesterite-phase copper-zinc-tin-sulfur compounds, respectively. , (220) and (312) diffraction indices. The experimental results show that the copper-zinc-tin-sulfur thin film with kesterite structure was prepared in this embodiment. Compared with Example 1, no small peaks (101) and (211) were observed in the analysis of the product of this example, probably because the annealing temperature was slightly lower and the degree of crystallization was slightly inferior to that of Example 1.

Embodiment 3-8:

The sample CZTS thin films prepared in Examples 3-8 are basically the same as those in Example 1, and there is no obvious difference in their composition, XRD pattern, Raman pattern and SEM pattern, and will not be repeated here.

In the above embodiments 1-8, the copper-zinc-tin-sulfur thin film is prepared by the coating method of spin coating, and the suitable spin coating speed is 500-6000 r/min for 10-50 seconds. Combined with the actual operating conditions, common methods such as dip coating, inkjet printing or screen printing can also be used for coating. According to the method of the present invention, copper-zinc-tin-sulfur thin films similar to those in Examples 1-8 can be prepared.

The protection content of the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the inventive concept, changes and advantages conceivable by those skilled in the art are all included in the present invention, and the appended claims are the protection scope.

Claims (10)

1. the process for preparing sol-gel of a copper-zinc-tin-sulfur thin film, is characterized in that, comprises following:

Step 1, the compound that will contain respectively copper, zinc, tin, sulphur is dissolved in solvent, makes stable copper-zinc-tin-sulfur precursor sol; Described solvent is alcohol or water and pure mixed solvent;

Step 2, be coated in described copper-zinc-tin-sulfur precursor sol in substrate, through heat treatment, obtains ormolu sulfur solar energy absorbing layer film.

2. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, it is characterized in that, in step 1, the described compound that contains copper is any one of copper nitrate, copper chloride, copper sulphate, the described compound that contains zinc is any one of zinc nitrate, zinc chloride, zinc sulfate, the described compound that contains tin is any one of stannous chloride, stannous sulfate, butter of tin, and the described compound that contains sulphur is thiocarbamide.

3. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, it is characterized in that, in step 1, the mol ratio of the described compound that contains copper, zinc, tin, sulphur is 2: (1～1.5): (1～1.5): (4～12).

4. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, it is characterized in that, in step 1, described solvent be in ethanol, methyl alcohol, ethylene glycol, isopropyl alcohol, glycerol any one or mix arbitrarily, in ethanol, methyl alcohol, ethylene glycol, isopropyl alcohol, glycerol any one or mix arbitrarily and the mixing of water.

5. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 4, is characterized in that, water and pure mol ratio are (0～2): 1.

6. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, is characterized in that, in step 1, the preparation temperature of described copper-zinc-tin-sulfur precursor sol is 25～180 ℃.

7. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, is characterized in that, in step 2, described painting method is spin coating, dip-coating, inkjet printing or silk screen printing.

8. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 7, is characterized in that, the rotating speed of described spin coating is 500～6000 rev/mins, continues 10～50 seconds.

9. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, is characterized in that, in step 2, described substrate is substrate of glass, the substrate of molybdenum sputtering glass or polyimides flexible substrates.

10. the process for preparing sol-gel of copper-zinc-tin-sulfur thin film according to claim 1, it is characterized in that, in step 2, described heat treatment method is, 100～350 ℃ of preannealing 0.5～60min in air, then 300～600 ℃ of degree annealing 2～90min in inert atmosphere; Wherein, described inert atmosphere is N ₂Or Ar.

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