Research On (Ag,Cu)(In,Ga)Se₂ Thin Film Fabricated By Pulse Electrodeposition Metallic Precursor And Selenization Processes

Copper indium gallium selenide(Cu(In,Ga)Se₂,CIGSe for short)thin-film solar cells have competitive advantages such as high radiation tolerance and high photoelectric conversion efficiency.So far,the highest conversion efficiency of CIGSe devices has reached 23.35%.There are vacuum methods and non-vacuum methods for preparing CIGSe thin films.The electrodeposition method in the latter can greatly reduce the production cost and has great development potential.The highest efficiency of CIGSe thin-film solar cells prepared by electrodepositing the prefabricated layer after the selenization process reaches 17.3%.In this paper,the electrodeposition method was used to prepare the CIGSe film,and the Ag element doping technology improved the quality of the CIGSe film prepared by the electrodeposition method and improved the device performance.The main research contents are as follows:During the electrodeposition process,the Cu thin film deposited on the Mo back electrode is prone to form"dendritic"clusters,resulting in a large roughness of the Cu layer,resulting in poor compositional uniformity of the CIGSe thin film,and a smooth and dense CIGSe thin film is essential for the preparation of high-quality solar cells critical.In this paper,by depositing an Ag layer on the surface of Mo thin film as a buffer layer,and comparing the roughness and crystallinity of the Ag layer prepared by immersion method and electrodeposition,a smooth and dense Ag layer was obtained on the Mo surface.Through the structural design of Mo/Ag/Cu,the"dendritic"morphology of the Cu thin film in the Mo layer was successfully eliminated.At the same time,the"island-like"morphology of In during nucleation is improved,the area of the gully between grains is reduced,and a denser In layer film is obtained.Vigorous hydrogen evolution reaction occurred during the electrodeposition of Ga,which reduced the current efficiency and resulted in a large number of depressions on the surface of the grains.By adjusting the electroplating temperature of the Ga electroplating solution,it is found that the hydrogen evolution phenomenon can be suppressed at low temperature,the current efficiency is improved,and a high-quality metal prefabricated layer is obtained.Deposition of Ga layer on Ag/Cu/In can also be beneficial to suppress this hydrogen evolution phenomenon.The metal prefabricated layer prepared by electrodeposition was annealed at300?for 30 min for alloying,and then the effects of substrate temperature and heat treatment time on the structure and morphology of CIGSe absorber film were studied.The research shows that the crystallinity of the ACIGSe film with the Ag buffer layer is improved,and the grain size is significantly larger than that of the CIGSe film without Ag.And the addition of Ag can effectively reduce the reaction temperature between the prefabricated layer and Se,and improve the degree of alloying.Finally,it was found that the VOC,JSC,FF,and photoelectric conversion efficiencies of ACIGSe thin-film solar cells were higher than those of CIGSe solar cells,and the highest efficiency reached 11.73%.The open-circuit voltage of high-efficiency ACIGSe cells is low,so the surface vulcanization treatment of ACIGSe films was carried out in this paper,and(Ag_1-x,Cu_x)(In_1-y,Ga_y)(Se_1-z,S_z)₂ was formed by reacting on the surface of the film.(ACIGSSe)to increase the surface bandgap,thereby increasing the open-circuit voltage of the device,and the ACIGSe thin-film solar cell after vulcanization was increased to 520 mV.