24.11% High Performance Perovskite Solar Cells by Dual Interfacial Carrier Mobility Enhancement and Charge‐Carrier Transport Balance

Abstract The open‐circuit voltage ( V OC ) and fill factor (FF) of perovskite solar cells (PSCs) are detrimentally weakened by carrier loss at the perovskite/charge transport layers (CTLs) interfaces. Herein, a dual interfacial modification strategy via placing Nb 2 CT x nanosheets with tailored optoelectrical properties induced by manipulating surface terminal groups at both perovskite/CTLs interfaces is employed. Such tactics not only concurrently implement carrier mobility enhancement of CTLs and interface energy‐levels offsets reduction. More importantly, electrical simulation indicates that the Nb 2 CT x with O terminal groups located at grain boundaries of the perovskite layer, can more efficiently conduct hole current to the hole transport layer, therefore achieving charge‐carrier transport balance in device. As a result, the synergy effect effectively elevates both the V OC and FF of the cells, reaching maximum values of 1.253 V and 81.07%, respectively, finally delivering progressively increased device power conversion efficiency (PCE) of 24.11% with negligible hysteresis. This PCE value ranks in the highest values to date for PSCs employing MXenes materials. Moreover, the optimized devices show better thermal and light stability than control devices. This work demonstrates a simple and effective dual interfacial modification method utilizing Nb 2 CT x for photovoltaic field, involving photodetectors, light‐emitting diodes, sensors, etc.