9:15 AM - 9:30 AM
▼ [18a-E102-2] Flexible Near-infrared Organic Photodetector with a Liquid Crystalline Phthalocyanine Derivative for Photoplethysmography
Keywords:flexible electronics, near-infrared photodetector, liquid crystalline semiconductor
In this study, flexible near-infrared (NIR) organic photodetectors (OPDs) (device structure: PET/Al/PEIE/active layer/Ag) were prepared on 25 μm PET substrates with active layer of a liquid crystalline organic semiconductor 1,4,8,11,15,18,22,25-octaoctyl-phthalocyanine (8H2Pc) and phenyl-C61-butyric acid methyl ester (PC61BM). At -5 V reverse bias, the external quantum efficiency (EQE) and shot-noise-limited detectivity (D*sh) at NIR wavelength of 740 nm of the flexible OPD without any bending strain were 9% and 1.1×1011 Jones, respectively. Measurements were also taken when the OPD was bent at a radius of 7.5 mm (thickness of the index finger of an average human subject). Even under strain, the device performed ideally with EQE of 5% and D*sh of 5.7×1010 Jones indicating very good mechanical flexibility and durability of the OPD. The potential of this device in vital signal monitoring was demonstrated by monitoring the photoplethysmogram of a human subject with a rigid NIR OPD in ambient conditions.