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


 In this study, near-infrared (NIR) organic photodetectors (OPDs) based on a liquid crystalline phthalocyanine derivative, octaoctyl-phthalocyanine (8H2Pc), and phenyl-C61-butyric-acid-methyl-ester (PC61BM) were realized. The champion device was found at the blend ratio of 1:1 by weight and exhibited responsivity of 0.2 A/W, external quantum efficiency of 29%, and shot-noise-limited specific detectivity of 1.3 × 1012 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 8H2Pc and PC61BM, resulting in smaller domain sizes and better separation of photo generated exciton pairs. Finally, the future prospect of the realized NIR OPD in practical applications was demonstrated by monitoring the vital signals of a human subject with a very simple experimental setup.