ABSTRACT Small‐molecule electron acceptors with donor–acceptor (D–A) structures have emerged as attractive materials for organic optoelectronics, yet achieving strong absorption in the short‐wavelength infrared (SWIR, 1000–3000 nm) region remains a fundamental challenge. Here, a resonant N—B←N unit, bis(borondifluoride)‐8‐imidazodipyrromethene (BIP), is introduced as a new electron‐deficient core for constructing D–A type SWIR acceptors. Incorporation of the BIP unit induces a pronounced bathochromic shift of 255 nm and affords an ultranarrow optical bandgap of 0.86 eV, with thin‐film absorption extending to 1450 nm. The resulting acceptor, BIP‐M1, exhibits a high molar extinction coefficient of 3.8 × 10 5 M − 1 cm − 1 and an exceptionally small Stokes shift of 0.054 eV, indicative of its strong SWIR absorption capability and suppressed nonradiative losses. Photodiode‐type organic photodetectors based on BIP‐M1 enable sensitive photoresponse over a broad spectral range from 300 to 1400 nm, delivering a responsivity of 0.18 A W − 1 and a specific detectivity of 3.93 × 10 11 Jones at 1200 nm, together with an ultralow Urbach energy of 19.19 meV. This study identifies resonant N—B←N units as powerful structural motifs for small bandgap molecular design and establishes BIP‐based small molecular acceptors as a promising platform for next‐generation SWIR optoelectronics.
LI et al. (Wed,) studied this question.