ASYMMETRIC NON-FULLERENE ACCEPTORS ECO-FRIENDLY SOLVENT-PROCESSED INDOOR ORGANIC PHOTOVOLTAICS

Abstract

Molecular structural tuning of non-fullerene acceptors (NFAs) has significantly progressed indoor organic photovoltaics (IOPVs). However, the use of additive-assisted chlorinated solvents in the processing of the photoactive layers remains a serious issue for the commercialization of IOPVs. We present the synthesis and photovoltaic properties of two asymmetric NFAs, IPC1CF3-BBO-IC2F and IPC1CF3-BBO-IC2Cl. These NFAs exhibited strong visible-light absorption with upshifted energy levels, as compared to the representative NFA Y6. Non-halogenated solvent-processed and additive-free IOPVs based on PM6:IPC1CF3-BBO-IC2F and PM6:IPC1CF3-BBO-IC2Cl exhibited high power conversion efficiencies (PCEs) of 29.3 and 26.8%, respectively, under a 1000-lux light-emitting diode (LED) illumination. Moreover, ternary IOPVs based on PM6:Y6:IPC1CF3-BBO-IC2F and PM6:Y6:IPC1CF3-BBO-IC2Cl exhibited impressive PCEs of 29.5 and 30.1% under 1000 lux-LED illumination and 33.6 and 32.7% under 1000 lux-fluorescent lamp illumination, respectively. These results highlight the effectiveness of structural modification using asymmetric end-groups to enhance the performance of IOPVs processed by eco-friendly solvent without using additives.