Multiple Exciton Harvesting at Zero-Dimensional/Two-Dimensional Heterostructures

Abstract

Heterostructures of zero-dimensional/two-dimensional (0D/2D) materials, especially quantum dots (QDs)/nanosheets (NSs), have attracted significant attention for extracting photogenerated electrons and holes. Herein, we report the dissociation of excitons at the heterojunction of CdSe (cadmium selenide) QDs and MoS2 (molybdenum disulfide) nanosheet utilizing steady-state and time-resolved spectroscopic techniques. Quasi type II semiconductor-like band energy alignment of the 0D/2D heterojunction facilitates exciton breaking via hole transfer from the QD to MoS2. Furthermore, we demonstrate the extraction of two holes from doubly excited QDs (created via high-power excitation) following the dissociation of a biexciton at the 0D/2D interface. This work is expected to provide a new approach of exploiting multiple exciton generation in quantum dot-sensitized solar cells by harvesting multiple carriers.