CdSe : Sb electrode for photoelectrochemical applications

Abstract

CdSe : Sb thin film electrodes with Sb³⁺ doping concentrations from 0 to 5 mol % were prepared in an aqueous alkaline medium (pH≈10) by a solution-growth technique. Use of these films was made as an active photoelectrode in an electrochemical photovoltaic cell comprising sulfide/polysulfide as an electrolyte redox couple and impregnated graphite as a counter electrode. The different cell characteristics such as current–voltage and capacitance–voltage in the dark, power output under 20 mW cm⁻² constant illumination intensity, built-in-potential, photo and spectral responses were examined. These characteristics were evaluated through such performance parameters as open-circuit voltage (V _oc), short-circuit current (I _sc), shunt and series resistances (R _sh and R _s), fill factor (ff%), efficiency (η%), junction ideality factor (n _d), lighted quality factor (n _L), built-in-potential (Φ_B) and the flat-band potential (V _fb). Careful inspection of calculated values of these parameters revealed that the cell performance was enhanced after doping the photoelectrode by trivalent antimony. Typically, the power conversion efficiency and fill factor improved from 0.14% to 0.24% and 42% to 51%, respectively, at a doping concentration of 0.1 mol % Sb³⁺ in CdSe. The incremental changes in the performance parameters, and consequently enhancement in the cell performance, have been explained on the basis of alterations in the electrode properties.