Grain Boundary Engineering with Cl-Terminated Ti2C Quantum Dots for Enhancing Perovskite Solar Cell Performance

The power conversion efficiency and stability of polycrystalline perovskite solar cells are compromised by grain-boundary-dominated ion migration. Herein, the grain boundaries of CH3NH3PbI3 films were engineered using Ti2C quantum dots. Ti2C quantum dots had a strong interaction with Pb2+ and I- ions, which retarded crystal growth, resulting in larger grain size and less grain boundary in perovskite films. Additionally, the Ti2C quantum dots at the grain boundary could anchor ions and passivate defects, increasing activation energy for ion hopping and reducing trap density. In consequence, perovskite films were used to fabricate solar cells with significantly improved efficiency and stability. These findings may allow the development of versatile grain boundary modifiers for perovskite optoelectronic devices that combine stability and efficiency.