Solution‐Processed Micro‐Nanostructured Electron Transport Layer via Bubble‐Assisted Assembly for Efficient Perovskite Photovoltaics

Abstract Organic–inorganic halide perovskite solar cells (PSCs) have attracted significant attention in photovoltaic research, owing to their superior optoelectronic properties and cost‐effective manufacturing techniques. However, the unbalanced charge carrier diffusion length in perovskite materials leads to the recombination of photogenerated electrons and holes. The inefficient charge carrier collecting process severely affects the power conversion efficiency (PCE) of the PSCs. Herein, a solution‐processed SnO 2 array electron transport layer with precisely tunable micro‐nanostructures is fabricated via a bubble‐template‐assisted approach, serving as both electron transport layers and scaffolds for the perovskite layer. Due to the optimized electron transporting pathway and enlarged perovskite grain size, the PSCs achieve a PCE of 25.35% (25.07% certificated PCE).