Multifunctional Iron‐Porphyrin Additive for Hole‐transporting Layer toward Efficient and Stable Perovskite Solar Cells

Spiro‐OMeTAD, as a crucial component of the hole‐transporting layer, exhibits limited mobility and conductivity, and the Li‐TFSI dopant is sensitive to water vapor, which imposed restrictions on the photovoltaic efficiency and durability of perovskite solar cells (PSCs). In this work, the iron‐porphyrin (FePP) molecule is introduced into Spiro‐OMeTAD solution as additive, which facilitate the oxidation process of Spiro‐OMeTAD, leading to the enhancement of hole mobility and hole extraction and transport. Besides, the surface Pb2+ defects in the perovskite film are cured by the presence of carboxylic acids (‐COOH) in FePP. As a result, the photovoltaic properties of PSCs with FePP additive have been improved in all aspects, and a PCE of 21.58% can be achieved. Moreover, the FePP additive can further anchor the Li+ ions in HTL to prevent it from being invaded by water vapor. Dramatically, the degradation of unencapsulated devices is suppressed significantly, the device with FePP additive retain 82.0% of its original PCE under 10‐20% RH after 7100 h, and maintain about 79.6% of its original PCE under 50‐60% RH after 1000 h. Thus, this study shows that the design and development of multifunctional HTL additives holds great potential for achieving highly efficient and durable PSCs.This article is protected by copyright. All rights reserved.