Low-voltage Electrochemical Preparation And Research Of Copper Indium Selenide Thin Film Materials

CuInSe₂(CIS)and Cu(In,Ga)Se₂(CIGS)are considered to be one of the most potential photovoltaic materials In the second generation of 21st century batteries due to their wide band gap width and large light absorption coefficient.There are some inherent problems in preparing semiconductor thin films by traditional electrodeposition,such as easy to produce holes,difficult to control the composition,poor morphology,etc.Based on the research of traditional electrodeposition technology at home and abroad,the vacuum system was introduced into the electrochemical deposition process to explore the deposition process of CuInSe₂ and Cu(In,Ga)Se₂ thin films.The main work is as follows:(1)The CuInSe₂ thin film was successfully prepared by low-voltage electrodeposition technology.Combined with electrochemical testing and material characterization,the influence of low-voltage system on the deposition of various elements was explored.The results show that the low pressure system can promote the formation of CuSe and H₂Se,which can promote the reduction of CuInSe₂ and effectively improve the film deposition rate.In the whole reaction process,the low voltage system is mainly controlled by diffusion,which can prepare the films in accordance with the stoichiometric ratio in a wide range of potential.By comparing with the atmospheric pressure system,CuInSe₂ films with larger particle size,stronger photocurrent response and a band gap of 1.31e V can be prepared under the low voltage system.By optimizing the process conditions,CuInSe₂ thin films with good stoichiometric ratio and quantum efficiency of 5.57%can be deposited in the system with air pressure of 3 k Pa,electric potential of-0.6V,InCl₃ concentration of 14mmol/L,H₂Se O₃ concentration of 8mmol/L and CuCl₂ concentration of2mmol/L.(2)The low pressure electrochemical deposition of Cu(In,Ga)Se₂ was realized,and the influence of low pressure system on the deposition of various elements was further explored.There is a competitive relationship between In³⁺and Ga³⁺in the deposition process,and the promotion of In³⁺by low pressure will lead to the decrease of Ga content in the film.Diffusion in low pressure system can inhibit the hydrolysis of Ga³⁺on the film surface and reduce the formation of Ga(OH)₃.Therefore,vacuum can inhibit the deposition of Ga³⁺.The deposition process is mainly affected by diffusion,and the composition does not change greatly with the increase of electric potential.The films that meet the stoichiometric ratio can be prepared in the range of large electric potential.The deposition rate is higher in the low voltage system,but the photoelectric performance is poor,and the band gap of the films prepared is1.07e V.By optimizing the process conditions,the system with air pressure of 3 k Pa,electric potential of-0.6V,Ca Cl₃ concentration of 8mmol/L,In Cl₃ concentration of 10mmol/L,Cu Cl₂concentration of 4mmol/L,H₂Se O₃ concentration of 8mmol/L can be prepared with good morphology.Cu(In,Ga)Se₂ thin films with flat surface.