Enhancing Small-Molecule Organic Photodetector Performance for Reflectance-Mode Photoplethysmography Sensor Applications

• Published in: ACS applied electronic materials 2020-05, Vol.2 (5), p.1280-1288
• Main Authors: Bilgaiyan, Anubha, Elsamnah, Fahed, Ishidai, Hiroshi, Shim, Chang-Hoon, Misran, Muhamad Affiq Bin, Adachi, Chihaya, Hattori, Reiji
• Format: Article
• Language: English
• ISSN: 2637-6113; 2637-6113
• DOI: 10.1021/acsaelm.0c00082

Organic photodetector performance for enhancing the sensing abilities of an organic photoplethysmography sensor was investigated. The optimized organic photodetector with an anode interlayer and a cathode interlayer showed a reverse dark current density of 22 nA cm–2 at −2 V and an external quantum efficiency of 53.3% at 0 V. This organic photodetector was fabricated monolithically with an organic light-emitting diode on a glass substrate to achieve a reflectance-mode photoplethysmography sensor, demonstrating the impact of organic photodetector device performance on the measured photoplethysmography signal for sensing applications. Furthermore, we estimated the optimal sensor design for circular geometry in terms of device area and distance between the organic light-emitting diode and organic photodetector to maximize the signal-to-noise ratio and lower the power consumption of organic photoplethysmography sensor devices. For the most favorable photoplethysmography sensor design, a signal strength of 130 mV with 600 μW power consumption was measured.