Simultaneous Enhancement of Quinoidal Resonance and Intermolecular Packing Enables Organic Photodetectors with High Detectivity Exceeding 10 ¹⁴ Jones below Si Bandgap

Achieving high specific detectivity ( D * ) in the shortwave infrared (SWIR) region remains challenging for organic photodetectors (OPDs) due to the limited photoelectric conversion efficiency and high dark current density ( J d ). Herein, we present a novel design strategy involving the extended conjugation of central unit to develop non‐fullerene acceptors (NFAs) with an exceptionally low bandgap ( E g opt ) of 0.69 eV. Single crystal X‐ray diffraction analysis reveals that QXIC‐4F exhibits a simultaneous enhancement in quinoidal resonance and diversified intermolecular stacking, resulting in redshifted absorption beyond 1200 nm, improved carrier mobility, reduced non‐radiative recombination, and lower trap density. As a result, OPDs based on QXIC‐4F achieve a high D * exceeding 10 14 Jones at 1040 nm under 0 V bias, significantly outperforming commercial silicon (Si)‐based detectors. Notably, a flexible 15 mm × 15 mm photoplethysmography (PPG) sensor and 256 × 256 organic photodiode image arrays (OPDIA) with 50 µm × 50 µm pixel pitch are successfully fabricated, demonstrating accurate heart rate monitoring and high‐quality SWIR imaging at room temperature.