Controlled thickness and morphology for highly efficient inverted planar heterojunction perovskite solar cells.

Recently, inverted planar heterojunction (PHJ) perovskite solar cells have been developed rapidly by numerous preparations and relative optimizations. Sequential solution deposition is easy to manipulate but it is difficult to control the thickness and morphology of perovskite films. In this article, we report an improved sequential deposition, named twice dipping-vapor solution deposition (TD-VSD) technology, to accurately achieve superior perovskite films. It is demonstrated that the morphology of perovskite films depended on the substrate temperatures as well as the dipping times. The resulting solar cells showed the power conversion efficiency as high as 11.77% based on the ideal thickness and morphology. This work provides a simple but effective fabrication to well control the perovskite films and enhance the power conversion efficiency for inverted PHJ solar cells.