Amine-Based Interfacial Engineering in Solution-Processed Organic and Perovskite Solar Cells

Solution-processed organic solar cells (OSCs) and hybrid perovskite solar cells (PvSCs) generally require appropriate transparent electrode with a low work function, which improves the electron extraction, increases the built-in potential, and suppresses charge recombinations. Hence, interfacial modifiers between the cathode and the photoactive layer play a significant role in OSCs and PvSCs, as they provide suitable energy-level alignment, leading to desirable charge carrier selectivity and suppressing charge carrier recombinations at the interfaces. Here, we present a comprehensive study of the energy-level mapping between a transparent electrode and photoactive layers to enhance the electron-transport ability by introducing amine-based interfacial modifiers (ABIMs). Among the ABIMs, polyethylenimine ethoxylated (PEIE) incorporating inverted OSCs shows enhanced power conversion efficiencies (PCEs) from 0.32 to 9.83% due to large interfacial dipole moments, leading to a well-aligned energy level between the cathode and the photoactive layer. Furthermore, we explore the versatility of the PEIE ABIM by employing different photoactive layers with fullerene derivatives, a nonfullerene acceptor, and a perovskite layer. Promisingly, inverted nonfullerene OSCs and planar n-i-p PvSCs with PEIE ABIM show outstanding PCEs of 11.88 and 17.15%, respectively.