Electrodeposition And Characterization Of Copper Gallium Selenide And Bismuth Selenide

Metal selenides have been widely applied in thin film solar cells and thermoelectric devices owing to their unique optical and electrical properties, which has attracted great attentions from academic to industrial community. Among various metal selenide fabrication technologies, electrodeposition is particularly attractive because of its simplicity, low cost, great scalability and continuous production of thin films with controlled component. In this paper, copper gallium selenide (CuGaSe2) thin film and bismuth selenide (Bi2Se3) nanowires have been successfully electrodeposited and characterized for their chemical compositions, surface morphologies and structures. The main conclusions are as follows:1. Copper gallium selenide thin films have been prepared by potentiostatic electrochemical method. The electrochemical behavior of the as-deposited film has been studied using Linear Sweep Voltammetry, revealing that copper, gallium and selenium can co-deposit in the potential range of-0.42～-0.82V vs. SCE. Deposition potential at-0.6V vs. SCE, temperature at25℃and pH value at2.3is found to be the best condition for preparation of thin film with compact morphology and the stoichiometric composition. It is found that the level of deposited Ga increases due to the rising of pH value and the addition of KSCN. The crystallinity can be improved greatly by annealing process; however, chemical composition has been changed slightly as well. The photoelectrochemical test shows a clear photo-voltage response for copper gallium selenide thin films with indicatively p-type conductivity. The optical characterization indicates copper gallium selenide thin films possessing a band gap of about1.68eV, which is suitable for solar energy harvesting.2. Bi2Se3nanowires have been successfully prepared by electrodeposition techniques on the anodic alumina template. The electrochemical behaviors were investigated by Cyclic Voltammetry in the electrolytic solution, revealing that bismuth undergoes an underpotential deposition to form Bi2Se3nanowire and-0.20V vs. SCE is the best deposition potential. The as-grown Bi2Se3nanowires were annealed at400℃in N2atmosphere, which is found that annealing can improve the crystallinity and change the chemical composition. The effect of surfactant was also studied, that can improve the composition and surface morphology of as-grown Bi2Se3nanowires.