Over 30% Efficiency in Halogen-Free Solvent-Processed Indoor Organic Photovoltaic Cells Enabled by Favorable Charge Carrier Dynamics.

Abstract

Indoor organic photovoltaics (IOPVs) offer a promising candidate for sustainable and self-sufficient power supply for Internet of Things (IoT) devices, where high efficiency critically depends on an in-depth understanding of charge carrier dynamics. Using two structurally similar IOPV systems, we demonstrate that multichannel exciton-to-charge conversion and low trap-state-density charge transport enable efficient charge generation and collection under indoor illumination. Exciton dissociation in PTQ10:AFIC occurs predominantly through charge-transfer (CT) states, with intrinsically faster state-to-state transitions relative to the PTQ10:ITCC system. This dynamic suppresses interfacial CT state accumulation, markedly reducing trap-assisted recombination-a major loss contributor under indoor illumination. Additionally, a favorable vertical phase distribution in the PTQ10:AFIC system promotes charge separation and transport, further suppressing recombination and enhancing charge collection. Notably, the halogen-free solvent-processed PTQ10:AFIC device delivers a remarkable efficiency of 30.4% (3000 K, 2000 lux), and exhibits promising scalability, with 1 and 6.25 cm² devices delivering 29.1% and 27.4% PCE, respectively, under the same 2000 lux illumination. This work demonstrates that favorable charge carrier dynamics and morphology synergistically suppress trap-assisted recombination in IOPVs, with such advantages disproportionately amplified under low-carrier-density indoor illumination conditions, highlighting the system's promising practical application potential.