Modification of energy levels by cetyltrimethylammonium bromide at the perovskite/carbon interface for highly efficient and stable perovskite solar cells

Carbon electrodes represent a promising strategy for creating stable and low-cost perovskite solar cells (PSCs). However, PSCs with carbon electrodes usually suffer from energy level mismatch at the perovskite/carbon interface. In this study, the application of cetyltrimethylammonium bromide (CTABr) as a self-assembled monolayer (SAM) is explored to optimize the energy level alignment. As a result, CTABr-modified cell shows a 22.26% improvement in power conversion efficiency (PCE) and delivers an impressive PCE of 11.26% with a stabilized current density of 15.59 mA/cm 2 . Moreover, in a damp environment (humidity ≈85%) without encapsulation, CTABr-modified PSCs remain at 90% and 57% of the initial efficiency after being aged for 240 and 480 h, respectively. This study paves a new route for preparing better-performing PSCs with carbon using a low-temperature process.