Comparative study of performance of CdTe, CdSe and CdS thin films-based photoelectrochemical solar cells

Polycrystalline films of CdTe and CdSe were electrodeposited onto titanium substrates from acidic baths, and, polycrystalline CdS thin films were prep ared by chemical bath deposition method. Due to surface treatment these fil ms show good photoelectrochemical behaviour in a polysulphide electrolyte w ith high conversion efficiency and stability. The solid-state parameters of annealed films are calculated and compared with those of unannealed film-b ased cells. Chemical etching is found to improve short-circuit current and fill-factor whereas photoelectrochemical etching technique improves the sta bility of photo-anode in polysulphide solution. Annealing promotes incipien t fusion of small crystallites and thereby reduces the grain boundaries whi ch are known to act as recombination centres for minority carriers and trap ping centres for majority carriers. The conversion efficiency and stability are found to improve by chemical etching of the semiconductor layer becaus e chemical etching pins Fermi level of CdTe, CdSe and Cds photoanodes and p romotes exchange current density. (C) 2000 Elsevier Science B.V. All rights reserved.