Photovoltaic devices based on electrochemical–chemical deposited CdS and poly3-octylthiophene thin films

Cadmium sulfide (CdS) is a well-known wide bandgap semiconductor for solar cell applications. In this work we report an electrochemical/chemical method to prepare CdS thin films on gold (Au)-coated glass substrates. 10 nm thick of titanium (Ti) film was first sputtered on glass surface to improve the adhesion between the subsequent sputtered Au film and the glass surface. Cadmium films were then electrochemically deposited on Au surface in an acidic solution with negative potential, and the obtained glass/Ti/Au/Cd samples were annealed in H2S atmosphere to convert Cd into CdS. XRD pattern of H2S-annealed Cd samples shows a hexagonal wurtzite phase in CdS with (0 0 2) as the preferential crystalline plane. Photovoltaic properties were clearly shown in hybrid heterojunctions of CdS and poly3-octylthiophene (P3OT) with Au as the top and the back metal contacts.