All-solid-state photoelectrochemical cell based on a polymer electrolyte containing a new transparent and highly electropositive redox couple

Abstract

The all-solid-state electrochemical photovoltaic cell n-CdSe//high molecular weight (HMW) PEO-based copolymer (modified PEO) 12–CsT/0.1 T 2//ITO was investigated. PEO is poly(ethylene oxide), CsT is 5-mercapto-1-methyltetrazole cesium salt, T 2 is di-5-(1-methyltetrazole) disulfide and ITO is indium tin oxide conducting glass. Electrodeposited polycrystalline CdSe electrodes were characterized using various techniques. X-ray diffraction data reveal growth of the hexagonal phase, whereas formation of the face-centered cubic structure is not excluded. Optical absorption studies demonstrate that CdSe possesses a direct bandgap energy of 1.75 eV. In the dark, the semiconductor/polymer electrolyte interface shows a rectifying behaviour typical of a non-ideal Schottky junction formed between a n-type semiconducting material and a metal or an electrolyte. Under white light illumination ( A=0.5 cm 2) at an incident intensity of 100 mW cm −2, the cell exhibits the following characteristics at 50°C: short-circuit current density, i sc=891 μA cm −2, open-circuit potential, V oc=0.52 V, fill factor, ff=0.37 and cell energy conversion efficiency, η=0.17%. It was demonstrated that the n-CdSe/solid polymer electrolyte interface is not homogeneous.