Keplerate-type polyoxometalate/semiconductor composite electrodes with light-enhanced conductivity towards highly efficient photoelectronic devices

Abstract

Metal oxide semiconductor (MOS) photoelectrodes hold great promise for new energy and environmental applications, from water splitting to photoelectronic devices. Here, we show an efficient polyoxometalate assistance strategy for the design and fabrication of MOS composite photoelectrodes with light enhanced conductivity. Four types of MOS based photoelectrodes were fabricated by a simple wet chemistry method through bounding TiO₂, SnO₂, WO₃, and ZnO with keplerate-type polyoxometalate (NH₄)₄₂[Mo^VI₇₂Mo^V₆₀O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] ({Mo₁₃₂}), respectively. In these photoelectrodes, {Mo₁₃₂} may act as a photo-induced electron acceptor/donor to accelerate electron transfer and then improve their conductivity efficiently. We further demonstrated that the 5% {Mo₁₃₂}/TiO₂ modified photoanode, in dye-sensitized solar cells (DSSCs), exhibits a power conversion efficiency (PCE) of 7.94% (31% improvement compared with that of the TiO₂-based cell (6.06%)).