Unique characteristics of 2D Ruddlesden-Popper (2DRP) for future photovoltaic application

Compared to the conventional three dimensional (3D) organic–inorganic halide perovskites, two dimensional (2D) Ruddlesden–Popper (RP) perovskites have attracted extensive attention in photovoltaics in recent years due to their excellent stability without sacrificing too much efficiency. The remarkable improvement in stability and rapid rise in efficiency are attributed to the unique properties caused by the quantum well structure due to the introduction of bulky organic ammonium spacers. In this perspective, we distill the outstanding features of the current state-of-the-art 2DRP perovskites, including enhanced stability, tunable exciton binding energy, out-of-plane oriented growth, and phase distribution. We also briefly discuss the potential technological development of RP perovskites as emerging semiconductor photovoltaic materials. The current challenging issues and future perspectives are also provided.