Poly(dithiazolfluorene-alt-selenadiazolobenzotriazole)-Based Blue-Light Photodetector and Its Application in Visible-Light Communication

Conjugated polymers have attracted broad interest from synthetic chemists and device developers in optoelectronic fields. In this study, we report a blue-light organic photodetector (OPD) based on our low-band and ambipolar PSeN polymer. Besides high stability, the device has excellent color-selective property in the visible-light region. At the bias of −3 V, the ratio of the external quantum efficiency (EQE) in blue to red is more than 10:1. Meanwhile, the device also shows very low dark current density of ∼21 nA/cm2 and high EQE more than 100% for blue light at the bias of −3 V. Then, the mechanism of the high EQE in single-sensitive layer structure devices is analyzed by considering the activation energy of traps and carrier injection. Furthermore, for portable purposes, a flexible blue-light OPD is designed. This OPD shows a great orthogonal light response to blue and orange contents in a white light source and will be a potential candidate in a two-channel visible-light communication system.