Organic Semiconductors with Halogenated Quinoid Terminals for Sensitive Short‐Wave Infrared Detection and Imaging

Abstract

ABSTRACT Short‐wave infrared (SWIR) detection and imaging is vital for optoelectronics, and solution‐processed organic semiconductors pave the way for developing large‐area, cost‐effective SWIR sensor arrays compatible with readout integrated circuits through facile pattern‐free processing. However, limited by the energy gap law, molecular skeleton vibrations, especially high‐frequency stretching modes like C─H bonds, induce accelerated non‐radiative decay in SWIR molecules, making the performance of SWIR organic photodetectors (OPDs), particularly in the long‐wavelength region, still lag behind that of commercial inorganic counterparts. Here we develop an efficient molecular engineering strategy to construct vibration‐suppressed SWIR molecules by employing halogenated quinoid terminals. Relative to their analogs with H atoms, halogenated semiconductors show attenuated exciton‐vibration coupling, decreased conformation and energy disorder, as well as enhanced intramolecular charge transfer, resulting in nearly doubled exciton lifetimes and reduced energy disorder from 103 to 66–83 meV, accompanied by 0.1–0.15 eV optical bandgap narrowing. The optimized SWIR OPDs achieve broadband photoresponse (0.3–1.6 µm) and high specific detectivities up to 2.11 × 10 11 Jones at 1.03 µm, overwhelming all reported OPDs with >1.4 µm response and comparable to Ge photodetectors in 0.9–1.4 µm range. Furthermore, we demonstrate an advanced active‐matrix OPD‐based SWIR imaging system prototype, showcasing applicability in diverse SWIR scenarios.