Robust Imaging through Light-Scattering Barriers via Energetically Modulated Multispectral Organic Photodetectors

Abstract

Emerging technologies, such as biomedical imaging and autonomous driving, rely on low-noise near infrared (NIR) photodetectors. Organic photodetectors (OPDs) offer tremendous potential for these applications because of their seamless integration and NIR photosensing capabilities; however, their high noise levels have constrained widespread commercialization. Herein, the study demonstrates a bulk heterojunction (BHJ) NIR OPD featuring an ultralow noise current of 2.18 fA, enabled by a newly synthesized electron-blocking layer (EBL), ((2,7-dicyano-9H-fluorene-9,9-diyl)bis(propane-3,1-diyl))bis(phosphonic acid) (3PAFCN). Through diverse energetic modulative design strategies, 3PAFCN enables the OPD to achieve homogenous surface properties, an elevated interfacial energy barrier, and optimized BHJ morphology, culminating in a notable specific detectivity of 2.50 x 1014 cm Hz0.5 W-1 at 808 nm illumination under white-noise conditions. These EBL design principles are broadly applicable for various photoactive materials. Demonstrations in single-pixel imaging highlight the exceptional clarity of the 3PAFCN-based OPD in low-light and foggy environments, underscoring the potential of OPD technology for advanced imaging applications.