Localization control of 2D/3D perovskite heterostructures at grain boundaries by amine-vapor-induced dimensionality reduction

Optimizing dimensional engineering of perovskite layer is critical to achieving long-term reliable and high efficiency perovskite solar cells (PSCs). However, organic cations in 2D perovskite inhibit carrier transport, showing negative effects on obtaining high efficiency 2D/3D perovskite heterostructure solar cells. In this work, the localization control of 2D perovskite on 3D perovskite layer is realized by directly transforming grain boundary into 2D perovskite. Our results demonstrates that post-treatment of perovskite film with amine vapors can selectively fabricate BA2PbI4 nanoparticles at grain boundaries of MAPbI3 layer to improve the humidity resistance and passivate defects. As a consequence, the devices based on perovskite films with localized 2D/3D heterostructures achieves a much-improved power conversion efficiency (PCE) and stability simultaneously.