Extending Photoresponse to the Near‐Infrared Region for Inverted Perovskite Solar Cells by Using a Low‐Bandgap Electron Transporting Material

Lead‐based organic–inorganic hybrid perovskite solar cells (PSCs) usually show an absorption edge around 800 nm, while the near‐infrared (NIR) wavelength beyond 800 nm cannot be utilized. Herein, a new indacenothiophene‐based electron transporting material (ETM), namely, ITCP‐M, is developed, which works to enhance electron extraction and electron transporting, and simultaneously extends photoresponses to the NIR region in MAPbI 3 ‐based inverted PSCs. Notably, the ITCP‐M‐based device exhibits a prominent photoresponse beyond 800 nm as observed from the external quantum efficiency (EQE) spectra, contributing to enhanced short‐circuit current density ( J sc ) without sacrificing the open‐circuit voltage and fill factor. As a result, inverted PSCs using ITCP‐M ETM delivers a high efficiency of 19.15%, representing one of the highest efficiencies in inverted PSCs using nonfullerene ETMs. This work provides a new and simple strategy to extend photoresponses to the NIR absorption region for MAPbI 3 ‐based inverted PSCs that can significantly improve device performance.