Improved Comprehensive Photovoltaic Performance and Mechanisms by Additive Engineering of TiCT MXene into CsPbIBr.

CsPbIBr is promising in the application of perovskite solar cells (PSCs) owing to its reasonable bandgap and good thermal stability. However, the reported power conversion efficiency (PCE) of the CsPbIBr solar cells is still much lower than that of the organic-inorganic hybrid PSCs, mainly due to relatively poor CsPbIBr crystal quality. Herein, additive engineering to the photoactive layer of CsPbIBr using the TiCT MXene nanosheets is reported. Thanks to the improved crystallinity/reduced defect density, together with the formation of the Schottky junction between the MXene nanosheets and CsPbIBr, enhanced separation and transfer of the photogenerated electron-hole pairs can be achieved for optimal MXene addition. A simple device configuration of ITO/SnO/TiCT-added CsPbIBr/P3HT/Ag can thus deliver a significantly boosted PCE of 15.10%, i.e., a ∼16.69% relative increment compared with that (12.94%) of the control device without adding MXene. In addition, the enhanced humidity resistance is achieved for the MXene-added CsPbIBr layers.