In Situ Self‐Assembly of Trichlorobenzoic Acid Enabling Organic Photovoltaics with Approaching 19% Efficiency.

Future industrialization of organic photovoltaics (OPVs) requires OPVs' processing to be more energy‐efficient and streamlined. Currently, only MoO3 and PEDOT:PSS are commonly used as the anode interface layer (AIL). The processing of MoO3 typically involves vacuum thermal evaporation with stringent thickness requirements. PEDOT:PSS necessitates separate processing and thermal annealing at temperatures exceeding 100 °C to eliminate moisture. This work utilized 3,4,5‐trichlorobenzoic acid (3CBA) as the AIL material. The distinct advantage of 3CBA over PEDOT:PSS and MoO3 is the in situ self‐assembly of 3CBA eliminates the need for separate solution processing, thermal evaporation, or thermal annealing. Remarkably, OPV devices incorporating PM6, BTP‐eC9, and the 3CBA AIL exhibited a superior efficiency of 18.2% compared to those with PEDOT:PSS (17.7%). By using nonhalogenated solvent, o‐xylene, to meet industrialization requirements, the devices achieved an exceptional efficiency of 18.8%, the highest reported value among devices with in situ self‐assembled interface layers. Furthermore, semi‐transparent devices with 3CBA displayed higher PCE and AVT values (13.1% and 25.7%) than their PEDOT: PSS counterparts, due to the weak absorption of the 3CBA AIL. This work contributes significantly to the high‐throughput production of OPVs by streamlining the AIL processing. [ABSTRACT FROM AUTHOR]