Improved Comprehensive Photovoltaic Performance and Mechanisms by Additive Engineering of Ti₃C₂T MXene into CsPbI₂Br

CsPbI₂Br 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 CsPbI₂Br solar cells is still much lower than that of the organic-inorganic hybrid PSCs, mainly due to relatively poor CsPbI₂Br crystal quality. Herein, additive engineering to the photoactive layer of CsPbI₂Br using the Ti₃C₂T 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 CsPbI₂Br, enhanced separation and transfer of the photogenerated electron-hole pairs can be achieved for optimal MXene addition. A simple device configuration of ITO/SnO₂/Ti₃C₂T-added CsPbI₂Br/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 CsPbI₂Br layers.