Research On Performance Of Zn-O-S Thin Films Prepared By CBD

CIGS thin-film solar cells with CdS as buffer layer have high efficiency,but leakage of Cd will cause harm to the environment.Zn-O-S is an alternative material to replace CdS as the buffer layer.It is a three-element material composed of Zn S and Zn O compound semiconductor crystal grains,whose band gap is adjustable,and is non-toxic and harmless.In various preparation methods of the Zn-O-S thin film,the CBD method has simple operation,short time consumption,and low cost.It is of certain value and significance to study the preparation of Zn-O-S thin films for photovoltaics by CBD.In this paper,the Zn-O-S thin film was prepared by the CBD method.It was found that the concentration of the reagent,the substrate material,and the deposition time all affected the growth of the Zn-O-S thin film.(1)The high ammonia concentration is easy to form Zn S grains,and cause the band gap of the film to increase.As the ammonia concentration increased,the S/S+O ratio increased,and the band gap value increased.The concentration of zinc sulfate and ammonium sulfate will affect the formation of complexes.By adjusting their concentration,the morphology and grain size of the film can be improved.The concentration of thiourea will affect the reaction rate,and then the crystalline quality of the film.(2)When the O content of the Zn-O-S film is high,the large-size grains will deposit in the film,the film is uneven,the crystalline is poor,and the band gap is small.The performance of the film can be improved by adjusting the O content of the film.(3)The density of the film deposited on the glass substrate was better than on the silicon substrate,but the crystallinity of the film grown on the silicon substrate was better than the glass substrate.However,after multiple depositions,the crystallinity of the film deposited on the glass would be improved.After optimizing the process conditions,a Zn-O-S buffer layer for photovoltaics was prepared.The process parameters were: zinc sulfate 0.02 M,ammonium sulfate 0.013 M,ammonia water 0.3 M,and thiourea 0.167 M.The grown Zn-O-S film was dense,and the grain size was large and uniform.The Zn-O-S thin film had a transmittance of 83% in the wavelength range of 350 nm-500 nm and the lowest band gap value of 3.57 eV.