Dual-Band Selective Organic Photodetector for Visible and Near-Infrared Light Imaging

Abstract

Dual-band selective organic photodetectors, which can change their responsive wavelengths by electrically switching their bias voltage, are essential for a comprehensive understanding of objects by detecting distinct optical information. Dual-band detection contributes to biomedical monitoring such as the blood oxygen percentage (SpO₂) measurement using red and near-infrared light. Having a stacked configuration of two different light-detecting active layers, dual-band selective organic photodetectors inherently exhibit a self-filtering effect: the front layer detects short-wavelength light, whereas the rear layer detects transmitted longer-wavelength light. Here, we present a dual-band selective organic photodetector capable of selectively detecting visible and near-infrared light at a low operating voltage of ≤1 V, achieving high specific detectivities at both wavelengths—1.5 × 10¹² Jones in the visible range and 1.8 × 10¹² Jones in the near-infrared range. Notably, the high specific detectivity in the near-infrared region was achieved by enhancing the photocurrent through the incorporation of an efficient near-infrared-responsive donor into the rear active layer. Attaining high specific detectivities in both the visible and near-infrared regions within a single device will facilitate high-resolution dual-band imaging.