Research On Harmless Preparation Technology Of Copper Indium Gallium Selenium Thin Film Battery

Solar energy is a clean,environmentally friendly renewable energy,the conversion of solar energy into electricity will allow mankind to completely solve the energy problem.Copper indium selenium（CIS）thin film solar cell has many advantages such as high photoelectric conversion efficiency,stable performance and so on.However,the research over the past 30 years has not led to the large-scale industrialization of CIS solar cells.The main reason is that the preparation technology of the battery absorption layer is complex and the equipment is expensive,which leads to the high cost of CIS solar cells.Among many battery absorption layer preparation technologies,electrodeposition method has the advantages of simple equipment,small investment,low cost,and large area preparation,which is expected to realize the large-scale industrialization of CIS solar cells.On the other hand,since Cd S is the buffer layer of commonly used copper indium gallium selenium（CIGS）batteries,the waste CIGS batteries may cause heavy metal pollution when recycled.To solve this problem,we used ZnS instead of Cd S to prepare ZnO and ZnO doped Al（AZO）by sol-gel-spin coating method,and further explored the influencing factors in the preparation process.The main work of this paper has the following aspects:（1）CIGS films were prepared on ITO by constant potential deposition method.The effects of different deposition voltage,annealing time and annealing temperature on the films were studied.X-ray diffraction（XRD）,scanning electron microscopy（SEM）and UV-Vis-NIR were used to analyze the composition,morphology and absorption characteristics of the films.The results show that the CIGS films prepared at p H value of 2.0 conform to the standard stoichiometric ratio.At the deposition potential of-0.46V,the prepared CIGS film can form the compound Cu In_0.7Ga_0.3Se₂ of copper pyrite at the annealing temperature of 450℃and annealing time of 90min.The film has a flat morphology,high density,suitable thickness,transmittance of less than 8%,and band gap width of 1.18e V.（2）ZnS was prepared by chemical water bath method.The ZnS prepared by ammonia system and sodium citrate system were compared.The results showed that ZnS could not be prepared by ammonia system,while ZnS could be prepared by sodium citrate system.Therefore,based on the sodium citrate system,the effects of different deposition time and annealing conditions on the preparation results were studied respectively.It was found that ZnS films with flat morphology and 159nm thickness could be obtained after deposition time of 3h,annealing temperature of 350℃and annealing time of 2h.（3）ZnO and AZO were prepared by sol-gel spin coating method.The effects of different spin coating times and annealing conditions on the composition,morphology,resistivity and band gap width of ZnO and AZO were studied.The results showed that the suitable conditions for the preparation of ZnO by sol-gel-spin coating method were the layer number of spin coating of 7,the annealing temperature in the early stage at 250℃,the time of 10min,and later annealing temperature of 450℃and time of 120min.The ZnO film prepared under this condition has a regular structure,a flat morphology,a transmittance of more than 80%,and a bandgap width of 3.31e V.The optimal conditions for the preparation of AZO were the layer number of spin coating of 7 times,the doping amount of Al of 5%,the early annealing temperature of 250℃,and the time of 10min,and the later annealing temperature of 450℃and time of120min.The transmittance of AZO prepared under this condition was above 80%.（4）On the basis of previous work,ITO/Mo/CIGS/ZnS/ZnO/AZO/C battery has been fabricated.However,the efficiencyof this solar cell is only 0.35%.It indicates that the preparation of the battery still has certain problem.It needs to improve the efficiency in the future studies.