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

Abstract

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 NiO_x/PCBM interfacial materials have been studied. A simple preheating method facilitates the formation of a relatively continuous and compact layer of well-crystallized CH₃NH₃PbI_3−xCl_x 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 ∼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.