Hierarchical SnO 2 hollow sub-microspheres for panchromatic PbS quantum dot-sensitized solar cells

Abstract

Abstract In contrast with the commonly used TiO 2 or ZnO electron transporters, SnO 2 , which possesses relatively low conduction band and high electron-mobility, is expected to facilitate the extraction of photogenerated electrons from quantum dots (QDs) to oxides in quantum dot-sensitized solar cells (QDSCs), especially for those narrow band gap QDs (e.g., PbS). In this work, hierarchical SnO 2 hollow sub-microspheres have been synthesized by a facile one-step hydrothermal process, and further studied for near infrared responsive PbS QDSCs. Morphology and structure characterizations reveal that these sub-micrometer-sized spheres (150–200 nm) with hollow interiors are assembled by numerous packed nanograins. The nanometer-sized grains ensure large specific surface area (∼69.2 m 2 g −1 ) and pore size (∼19 nm) for high QD loading, while the sub-micrometer-sized spheres function as efficient light scatters and robust electron transporting structures. As a result, these superior features make such hierarchical SnO 2 architectures very promising candidates for photovoltaic application. Based on the multifunctional photoelectrode constructed with hierarchical SnO 2 hollow architectures, an appreciable power conversion efficiency up to 1.34% has been achieved for a PbS QDSC, coupled with interface engineering through TiO 2 coating and CdS passivation. This work offers a promising design for developing high performance QDSCs.