The State-of-the-Art Solution-Processed Single Component Organic Photodetectors Achieved by Strong Quenching of Intermolecular Emissive State and High Quadrupole Moment in Non-Fullerene Acceptors.

Abstract

A bulk-heterojunction (BHJ) blend is commonly used as the photoactive layer in organic photodetectors (OPDs) to utilize the donor (D)/acceptor (A) interfacial energetic offset for exciton dissociation. However, this strategy often complicates optimization procedures, raising serious concerns over device processability, reproducibility and stability. Herein, we demonstrate highly efficient OPDs fabricated with single-component organic semiconductors via solution-processing. The non-fullerene acceptors (NFAs) with strong intrinsic D/A character are used as the photoactive layer, where the emissive intermolecular charge transfer excitonic (CTE) states are formed within <1ps, and efficient photocurrent generation is achieved via strong quenching of these CTE states by reverse bias. Y6 and IT-4F based OPDs show excellent OPD performances; low dark current density (∼10-9 A cm-2 ), high responsivity (≥ 0.15 A W-1 ), high specific detectivity (> 1012 Jones) and fast photo-response time (< 10 µs), comparable to the state-of-the-art BHJ OPDs. Together with strong CTE state quenching by electric field, these excellent OPD performances are also attributed to the high quadrupole moments of NFA molecules, which can lead to large interfacial energetic offset for efficient CTE dissociation. Our work opens a new way to realize efficient OPDs using single-component systems via solution-processing and provides important molecular design rules. This article is protected by copyright. All rights reserved.