Multifunctional and Multicolor Perovskite-CdSe Quantum Dots Diodes for Pulse Oximetry.

A conventional pulse oximeter system is composed of two light sources with different peak emission wavelengths and a photodetector. Integrating these three independent components into one single device will absolutely simplify the system design and create a miniaturized size of the product. Here, we demonstrate a bilayer perovskite-CdSe quantum dot (hereafter perovskite-QD) diode capable of voltage-tunable green/red emission and photodetection. The proposed diode also presents an intriguing feature of simultaneous light emission and detection, which is explored as regards the diode being used as a photoconductor when the positive bias is larger than the built-in voltage. The multifunctional and multicolor diode is further employed in a reflective pulse oximeter system, as either the multicolor light sources or the sensing unit in the system provide accepted and trustful results for heart rate and arterial blood oxygenation. Our work provides a possible avenue for the simplification of the pulse oximetry with a compact and miniaturized design in the future.