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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 × 1013 Jones at λ = 1100 nm, while speed and linearity are preserved. By employing a small-molecule-acceptor IR6, EQE = 35% and D* = 4.1 × 1012 Jones are obtained at λ = 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.
Luong et al. (Mon,) studied this question.