Self-Filtering Narrowband Organic Photodetectors for Non-Invasive Blood-Oxygen Monitoring

Increasing demands on medical diagnostics, miniaturized spectroscopy, and optical communication raise the need for developing compact photodetectors with spectral selectivity. Narrowband photodetector stands out as a promising solution. Self-filtering narrowband organic photodetectors respectively peaked at 660 nm and 860 nm are fabricated following the exciton dissociation narrowing (EDN) strategy. A full width at half maximum (FWHM) of 83.0 nm with a peak EQE of 59% at 860 nm and 72.9 nm with a peak EQE of 59% at 660 nm are achieved. The narrow-band photodetectors show excellent stability that maintained a high specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1}.{2}\times {10}^{{12}}$ </tex-math></inline-formula> Jones at 860 nm and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${7}.{6}\times {10}^{{11}}$ </tex-math></inline-formula> Jones at 660 nm after being aged in air at room temperature for 280 days. By integrating the self-filtering narrowband photodetectors peaked at 660 nm and 860 nm with red and infrared LEDs, respectively, a device for real-time non-invasive monitoring of arterial PPG signals, blood oxygen saturation, and heart rates was realized.