Preparation And Characterization Of Chalcogenide Photoelectric And Thermoelectric Films By Electrodeposition

With the increase of energy demand and the reduction of non renewable energy reserves, rational exploitation and utilization of energy, especially renewable energy, is becoming more and more significant. Solar energy as a clean and pollution-free, large reserves energy, can achieve photoelectric conversion through solar cells. Thermoelectric materials can transfer exhaust gas, heat and solar radiation heat into electricity, which alleviates the energy crisis effectively. CuInSe2 and CuInS2 have become promising photovoltaic materials because of their advantages such as high thermal stability and high optical absorption coefficient. Cu2-xSe and Bi2Se3 as binary thermoelectric materials have also become a hot research topic at home and abroad.In this paper, CuInSe2, CuInS2, Cu2-xSe and Bi2Se3 thin films were prepared by electrodeposition. The effects of electrical deposition technologies and post treatment process on phase, morphology and other properties of films were investigated. The prepared films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and spectrophotometer.(1) CuInSe2 films were prepared by one-step electrodeposition, and the effects of electrical deposition technologies such as deposition potential, pH, temperature of solution, deposition time, complexing agent on phase and morphology of films were investigated. Results show that CuInSe2 thin films can be obtained under conditions of CuCl2·2H2O, InCl3, SeO2, sodium citrate with concentrations of 6mmol/L,8mmol/L,6mmol/L,5mmol/L respectively, pH 2.0, deposition potential-0.5V, solution temperature 20℃ and deposition time 30min. Film consists of many particles with diameters about 0.5-1.5μm distribute on the surface with dense, continuous morphology.(2) CuInS2 photoelectric thin films were prepared by two-step method of post electrodeposition vulcanization. The effects of deposition potential, deposition time, solution temperature, curing process on phase and morphology of films were investigated. Results show that CuInS2 precursor films can be obtained under conditions of CuCl2·2H2O, InCl3, Na2S2O3·5H2O, sodium citrate with concentrations of 10mmol/L, 10mmol/L, 100mmol/L, 1.25mmol/L respectively, pH 3.5, deposition potential-1.0V, deposition time 30min and solution temperature 25℃. CuInS2 thin films with good crystallinity were obtained by curing precursor films at 350℃ for 6h. It consists of many lumps with uniform size, and there are holes distribute on the surface after heat treatment. The precursor and curing films were all found containing copper, indium and sulfur elements. It is found that the content of sulfur in the films was obviously increased after curing.(3) Cu2-xSe thermoelectric thin films were prepared by one-step electrodeposition. The effects of deposition potential, pH on phase and morphology of films were investigated. Results show that Cu2-xSe thin films can be obtained under conditions of CuCl2·2H2O, SeO2, sodium citrate with concentrations of 6mmol/L,12mmol/L,50mmol/L, pH 2.5, deposition potential -0.5V, solution temperature 20℃ and deposition time 30min. It consists of many rods with about 1μm length. The film is dense, continuous, and smooth.(4) Bi2Se3 thermoelectric thin films were prepared by electrodeposition, and films were handled with heat treatment. The effects of deposition potential, deposition time, solution temperature, heat treatment on phase and morphology of films were investigated. Results show that Bi2Se3 thin films can be obtained under conditions of Bi2O3, SeO2 with concentrations of 4mmol/L,5mmol/L, deposition potential -0.4V, pH 1.0, deposition time 20min and solution temperature 25℃. Bi2Se3 films with good crystallinity can be obtained by heat treatment at 350℃ for 2h or 400℃ for 1h. It consists of particle aggregations and rod like crystals with irregular distribution.