CuInS₂ Quantum Dots Coated with CdS as High-Performance Sensitizers for TiO₂ Electrodes in Hydrogen Production and Photovoltaic Applications

Abstract

We demonstrate a high-performance photoanode composed of a nanoporous TiO2 film co-sensitized with CuInS2 quantum dots (QDs) and CdS polycrystalline layers, exhibiting the excellent performance in both photosynthetic and photovoltaic applications. The CuInS2 QDs are synthesized via a solvothermal route and the average particle size is 3.5 nm, attached on TiO2 surface by assistance of bifunctional linker. The subsequent CdS layers are coated using successive ionic layer adsorption and reaction. The back reaction of interfacial charge recombination can be prohibited by the CdS coating. Besides, the CdS shell coating results in remission of the quantum confinement of the QDs, leading to a widening of optical absorption spectra. In a photosynthetic photoelectrochemical cell, this heterostructural electrode exhibits a saturated photocurrent of 16 mA cm-2 under illumination of AM 1.5G at full sun intensity. On the other hand, this high-performance photoanode exhibits a power conversion efficiency of 4.08% in a sandwich-type quantum dot sensitized solar cells (QDSSCs) using CuS as counter electrode. The superior performance is mainly ascribed to the extension of the absorption spectra and significant enhancement of charge separation via CdS coating.