Zero-Dimensional Organic-Inorganic Perovskite Variant: Transition between Molecular and Solid Crystal.

Low-dimensional organic-inorganic halide perovskites (OIHPs) have attracted intense interest recently for photovoltaic applications, due to their markedly high chemical stability as compared to the widely studied three-dimensional (3D) counterparts. However, low-dimensional OIHPs usually give much lower device performance than the 3D OIHPs. In particular, for the zero-dimensional (0D) OIHPs, it is believed that the strong intrinsic quantum-confinement effects can lead to extremely low carrier motility, which can severely limit the photovoltaic performance. Herein, we predict a new family of 0D perovskite variants that, surprisingly, exhibit outstanding optoelectronic properties. We show that the "atypical" carrier mobility of these new 0D perovskites is attributed to the strong electronic interaction between neighboring octahedrons in the crystal. These findings also suggest a new materials design strategy for resolving the low-performance issue commonly associated with the low-dimensional OIHPs for photovoltaic applications.