Solution-processed near-infrared organic photodetector based on a liquid crystalline phthalocyanine derivative for vital signal monitoring

• Published in: Japanese Journal of Applied Physics Vol. 62; no. SC; p. SC1013
• Main Authors: Kabir, Shahriar, Takayashiki, Yukiko, Hanna, Jun-ichi, Iino, Hiroaki
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.04.2023; Japanese Journal of Applied Physics
• Subjects: bulk heterojunction; Butyric acid; Excitons; liquid crystalline semiconductor; Liquid crystals; Near infrared radiation; near-infrared photodetector; organic semiconductor; Photometers; Quantum efficiency; Signal monitoring; Spin coating
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/acaa42

In this study, near-infrared (NIR) organic photodetectors (OPDs) based on a liquid crystalline phthalocyanine derivative, 1,4,8,11,15,18,22,25-octaoctyl-phthalocyanine (8H 2 Pc), and phenyl-C61-butyric acid methyl ester (PC 61 BM) were realized. The best device had a blend ratio of 1:1 by weight and exhibited responsivity of 0.2 A W −1 , external quantum efficiency of 29% and shot-noise-limited specific detectivity of 1.3 × 10 12 Jones at 740 nm with −1 V reverse bias. This notable performance was attributed to the uniformity and smooth surface morphology of the spin-coated active layer and the intermixed condition of the liquid crystalline 8H 2 Pc and PC 61 BM, resulting in smaller domain sizes and better separation of photogenerated exciton pairs. Finally, the future prospects of the realized NIR OPD in practical applications were demonstrated by monitoring the vital signals of a human subject with a very simple experimental setup.