Indoor Organic Solar Cells: Toward Enhancing Indoor Light Energy Harvesting Using Non-Fullerene Acceptors

This study investigates the performance and stability of organic solar cells (OSCs) employing nonfullerene acceptors (NFAs) under indoor light-emitting diode (LED) illumination. Using PM6 as the polymer donor and comparing PC70BM fullerene with ITIC-M, Y6-O, and Y7 NFAs, devices were fabricated and characterized electrically and optically. Under an illumination of 1500 lx LED light, power conversion efficiencies (PCEs) reached up to 20% with ITIC-M, outperforming the other acceptors. Electrical modeling using a single-diode equivalent circuit correlated experimental data with transport and recombination mechanisms, revealing that NFAs and fullerene-based devices exhibit distinct degradation pathways. Stability tests under continuous 1000 lx LED exposure showed that PM6:ITIC-M devices retained over 96% of their initial PCE after 511 h, indicating superior operational stability. The results demonstrate that NFA-based OSCs, particularly PM6:ITIC-M, are promising candidates for efficient, stable, and cost-effective indoor photovoltaic energy harvesting, suitable for powering low-energy devices.