Highly Sensitive Resonance-Enhanced Organic Photodetectors for Shortwave Infrared Sensing

Shortwave infrared (SWIR) sensing has various applications, including night vision, remote sensing, and medical imaging. SWIR organic photodetectors (OPDs) offer advantages such as flexibility, cost-effectiveness, and tunable properties; however, lower sensitivity and limited spectral coverage compared to inorganic counterparts are major drawbacks. Here, we propose a simple yet effective and widely applicable strategy to extend the wavelength detection range of the OPD to a longer wavelength, using a resonant optical microcavity. We demonstrate a proof-of-concept in PTB7-Th:COTIC-4F blend system, achieving external quantum efficiency (EQE) > 50% over a broad spectrum (450-1100 nm) with a peak specific detectivity (D*) of 1.1 x 10(13) Jones at lambda = 1100 nm, while speed and linearity are preserved. By employing a small-molecule-acceptor IR6, EQE = 35% and D* = 4.1 x 10(12) Jones are obtained at lambda = 1150 nm. This research emphasizes the importance of optical design in optoelectronic devices, proposing a simpler method to broaden the photodetection range compared with traditional approaches using narrow optical gap absorbers.