LAUSR

Electron transport layers (ETLs) with pronounced electron conducting capability are essential for high performance planar photovoltaics, with the great challenge being that the most widely used metal oxide ETLs unfortunately have intrinsically low carrier mobility. Herein is demonstrated that by simply addressing the carrier loss at particle boundaries of TiO2 ETLs, through embedding in ETL p-n heterointerfaces, the electron mobility of the ETLs can be boosted by three orders of magnitude. Such embedding is also encouragingly favorable for both inhibiting the formation of rutile phase TiO2 in ETL, and initiating the growth of the top high-quality and large-grain perovskite films with less defect states. By virtue of these merits, creation of formamidinium lead iodide perovskite solar cells (PSCs) with a champion efficiency of 25.05% is achieved, setting a new benchmark for planar PSCs employing TiO2 ETLs. Unencapsulated PSCs employing such ETLs also deliver much-improved environmental stability, i.e., more than 80% of their initial efficiency after 9000 h of air storage under RH of 40%, and over 90% of their initial efficiency at maximum power point under continuous illumination for 500 h. Further work exploring other laser-generated p-type nanocrystals for embedding warrants the proposed strategy as a universal alternative for addressing the low-carrier mobility of metal oxide based ETLs, from the view point of particle boundaries engineering. This article is protected by copyright. All rights reserved.