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

Oh, Seunghyun; Jo, Suyeon; Lee, Ji Hyeon; Ko, Hyun Woo; Kim, Tae Hyuk; Seo, Paul Hongsuck; Lee, Gyeong Min; Shim, Eun Soo et al. · Adv Mater · 2025

basic_science · Level V

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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 × 10<sup>14</sup> cm Hz<sup>0.5</sup> W<sup>-1</sup> 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.