Preheating-assisted deposition of solution-processed perovskite layer for an efficiency-improved inverted planar composite heterojunction solar cell

Planar heterojunction perovskite solar cells have received a lot of attention due to their great potential, such as low-cost and rapidly improving performance. However, the poor fill surface coverage and numerous pinholes usually exist in the organic-inorganic hybrid perovskite layers, leading to undesirable electron-hole recombination. Herein, inverted cell structures based on NiOx/PCBM interfacial materials have been studied. A simple preheating method facilitates the formation of a relatively continuous and compact layer of well-crystallized CH3NH3PbI3-xClx perovskite by a one-step solution process, which can minimize film defects and thus improve the charge extraction dissociation and transport abilities at the interface. As a result, synchronized improvements in photovoltage (V-oc), photocurrent (J(sc)) and fill factor (FF) lead to similar to 25% enhanced power conversion efficiency (PCE), compared to solar cells using conventional perovskite films. Our study highlights a simple and effective method to improve the perovskite film quality and the photovoltaic performance of inverted perovskite solar cells.