Cu₂ZnSnS₄ Nanoparticle Sensitized Metal–Organic Framework Derived Mesoporous TiO₂ as Photoanodes for High-Performance Dye-Sensitized Solar Cells

We present a facile hot injection and hydrothermal method to synthesize Cu₂ZnSnS₄ (CZTS) nanoparticles sensitized metal–organic frameworks (MOFs)-derived mesoporous TiO₂. The MOFs-derived TiO₂ inherits the large specific surface area and abundantly porous structures of the MOFs structure, which is of great benefit to effectively enhance the dye loading capacity, prolong the incident light traveling length by enhancing the multiple interparticle light-scattering process, and therefore improve the light absorption capacity. The sensitization of CZTS nanoparticles effectively enlarges the photoresponse range of TiO₂ to the visible light region and facilitates photoinduced carrier transport. The formed heterostructure between CZTS nanoparticles and MOFs-derived TiO₂ with matched band gap structure effectively suppresses the recombination rates of photogenerated electron/hole pairs and prolongs the lifespan of the carriers. Photoanodes based upon CZTS/MOFs-derived TiO₂ photoanodes can achieve the maximal photocurrent of 17.27 mA cm^–2 and photoelectric conversion performance of 8.10%, nearly 1.93 and 2.21 times higher than those of TiO₂-based photoanode. The related mechanism and model are investigated. The strikingly improved photoelectric properties are ascribed to a synergistic action between the MOFs-derived TiO₂ and the sensitization of CZTS nanoparticles.