Electrodeposition Of P-type CuSCN Thin Films By Weak Basic Aqueous Electrolytes

Nanocrystal photo-eletrochemical cells (NPC) have been widely studied due to their low cost and simple technology. In this paper, developments on NPC cells and its solid hole conducting layers were reviewed. Electrodeposition of CuSCN thin film as the hole conducting material as well as its filling in ZnO rod arrays was investigated.A stable aqueous electrolyte solution containing Cu2+ and SCN- was prepared by adding triethanolamine (TEA, N(CH2CH2OH)3) to chelate with Cu(II) cations. The electrolyte solutions were basic with pH values in the range of 8.5~9 and could be used in the electrodeposition of CuSCN as hole conducting layer on the substrates which were afraid of acid from acidic etching. The p-type CuSCN thin films with high transmittance were potentiostatically deposited on ITO glass substrates by the as-prepared aqueous electrolyte solution. The crystalline morphology, phase composition, chemical composition, optical transmittance and energy band gap of CuSCN films were analyzed by FESEM, XRD, XPS and UV-VIS. The influence of the electrodepositon parameters, such as applied potentials, electrolyte components, depositon time and deposition temperatures on particle morphology, phase and stoichiometry of the CuSCN films were investigated.Nucleation and growth of CuSCN on ZnO rod arrays was studied. Homogeneous growth of CuSCN on ZnO rod arrays should be attributed to the reverse bias mechanism leading to prior growth on the bare ZnO rods. The contact between the n- and p-type semiconductors had a clear rectification, indicating a good electrical contact formed between the large internal surface of ZnO rod arrays and the embedded CuSCN. Optical measurements exhibited diffused transmittance spectra, which mainly depended on the nanostructure of ZnO rod arrays.