2026-10-12T14:20:20Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34030664 2026-09-30T08:03:50Z category_1 category_7 category_14 category_873 category_39 portal_63 item_type_6 month_year_09_2026

Mitigating the Trade-Off between Bandgap Narrowing and Trap-Limited Transport for Low-Noise Organic Short-Wave Infrared Photodetectors Ohhyun Kwon (24565715) Un-Hak Lee (5815223) Gyeong Min Lee (22837776) Seunghyun Oh (8202096) Se Jeong Park (1954663) Yeonsu Choi (11534020) Hyungju Ahn (1488403) Sang Heon Lee (3915581) Seunghyun Rhee (3961988) Dong Ryeol Whang (1365735) SungWoo Nam (1437964) Seo-Jin Ko (1466557) Jae Won Shim (1571971) Biophysics Medicine Molecular Biology Chemical Sciences not elsewhere classified Ecology wave infrared detection enhanced quinoidal character elevated dark current dependent collection bottlenecks dark current drift dark current density corresponding specific detectivity 88 × 10 47 × 10 1200 nm highlight 1200 nm even extending swir response mediated transport losses study introduces fc2bs energetic disorder relative enabling stable low cm · hz 11 </ sup noise organic short energetic disorder 1263 nm limiting noise absorption extending transport penalties related transport limited transport typically achieved suppressed bias reduced structural promising route promising molecular optical bandgap low bias fc2bs achieves design motif bias operation benzoselenadiazole substitution based device bandgap systems bandgap narrowing 98 ev 14 pw Solution-processed organic photodetectors present a promising route to short-wave infrared detection; however, accessing the spectral region beyond 1200 nm requires sub-1.0 eV organic absorbers, typically achieved through strong intramolecular charge transfer, enhanced quinoidal character, and extended π-conjugation; whereas, conformational and energetic disorder in such narrow-bandgap systems can contribute to trap-mediated transport losses and elevated dark current. This study introduces Fc2BS and Fc2BT, narrow-bandgap nonfullerene acceptors differing solely in the π-bridge unit (benzoselenadiazole vs benzothiadiazole), to examine how chalcogen substitution influences bandgap narrowing and trap-related transport in sub-1.0 eV organic absorbers. Fc2BS achieves an optical bandgap of 0.98 eV with absorption extending to 1263 nm, where benzoselenadiazole substitution is associated with reduced structural and energetic disorder relative to benzothiadiazole. Compared to the Fc2BT-based device, the Fc2BS-based device suppresses trap density by 8-fold and extends the critical carrier transport length by an order of magnitude, mitigating the dark current–responsivity trade-off and achieving a dark current density of 7.88 × 10^–9 A cm^–2 with an EQE of 12.5% at 1200 nm even at a low bias of −0.1 V, while enabling stable low-bias operation through suppressed bias-dependent collection bottlenecks and dark current drift. A directly measured noise equivalent power of 2.14 pW and corresponding specific detectivity of 1.47 × 10¹¹ cm·Hz^1/2·W^–1 at 1200 nm highlight the benzoselenadiazole π-bridge as a promising molecular-design motif for extending SWIR response while limiting noise and transport penalties. 2026-09-30T00:00:00Z Text Journal contribution 10.1021/acsnano.6c10554.s001 https://figshare.com/articles/journal_contribution/Mitigating_the_Trade-Off_between_Bandgap_Narrowing_and_Trap-Limited_Transport_for_Low-Noise_Organic_Short-Wave_Infrared_Photodetectors/34030664 CC BY-NC 4.0