Solution-processed organic infrared photodetectors operating beyond 1.4 μm for sensitive environmental monitoring

Photon energies in the short-wave infrared (SWIR) beyond 1.4 μm enable access to vibrational-overtone signatures of O-H, C-H, and N-H bonds in pollutants and waste materials, offering an imaging-based nondestructive approach for environmental monitoring. However, current SWIR imaging technologies rely on costly epitaxial semiconductors incompatible with monolithic integration, limiting consumer-grade deployment. Here we report a cost-effective organic SWIR imager with response beyond 1.4 μm, integrating high-detectivity organic photodetectors (OPDs) with amorphous silicon thin-film transistors via solution processing. The developed highly-ordered SWIR organic semiconductors with (halogenated) thiophene-fused quinoid terminals exhibit ultra-narrow optical bandgaps of 0.68-0.94 eV and Urbach energies down to 23 meV. The SWIR OPDs achieve spectral response from 0.3 μm to 1.5-1.7 μm with responsivities up to ∼0.1 A W^-1 and specific detectivities of 2.03-4.60 × 10¹⁰ Jones at 1.4 μm. The active-matrix SWIR imagers achieve accurate oil-leak monitoring in simulated seawater (R² = 0.993-0.997) and reliable waste-textile classification (silhouette score = 0.824), demonstrating their capabilities in environmental monitoring.