LAUSR

Organic photodetectors (OPDs) based on co‐evaporated bulk heterojunctions (BHJs) have demonstrated their potential for industrially relevant fabrication of high‐efficiency devices. However, acceptor materials choice is still dominated by fullerenes, which show sub‐optimal performance due to deep trap states originating from unfavorable BHJ morphology. Herein, the non‐fullerene acceptor Cl6‐SubPc is used to replace C60 in 2‐((8‐methyl‐8H‐thieno[2,3‐b]indol‐2‐yl)methylene)−1H‐cyclopenta[b]naphtha‐lene‐1,3(2H)‐dione (MPTA):C60 BHJs. Through active layer thickness tuning, the effective Cl6‐SubPc intercalation into MPTA domains is achieved for a highly intermixed BHJ morphology. This results in a high yield of interfacial charge‐transfer states, which are readily quenched under electric field for efficient OPD photoresponse. In comparison to C60‐based devices, Cl6‐SubPc suppresses the residual MPTA aggregation and the adduct generation with MPTA, preventing deep‐trap state formation. As such, non‐fullerene acceptor‐based OPDs are highly promising for trap‐free photodetection, enabling superior performances under low‐light illumination.