Enhancing Exciton Utilization via Förster Resonance Energy Transfer Enabling Ternary Organic Solar Cells With Low Nonradiative Energy Loss

Reducing nonradiative recombination energy loss (Δ E nonrad ) is a critical pathway for enhancing the efficiency of organic solar cells (OSCs). This study investigates Förster resonance energy transfer (FRET) and the mechanisms contributing to energy losses, employing electroluminescence (EL) spectroscopy as a key analytical tool. By incorporating the guest material IDIC into PM6:IMC6‐4Cl devices, the ternary OSC achieves a power conversion efficiency of 15.69% and a reduced energy loss ( E Loss ) of 0.62 eV. In the PM6:IMC6‐4Cl:IDIC ternary system, more sufficient exciton transfer from the guest acceptor IDIC to the host system was mediated by Förster resonance energy transfer (FRET). This mechanism enhances exciton utilization, thereby minimizing energy losses in the ternary systems. The incorporation of IDIC not only improves energy alignment but also leverages FRET to improve overall device efficiency. These findings underscore the potential of employing ternary FRET systems in OSCs and offer insights into selecting guest molecules to accelerate energy transfer.