Luminescent properties of benzothiazole derivatives and their application in white light emission

Three benzothiazole derivatives, N-[4-(benzothiazol-2-yl)-3-hydroxyphenyl]-octanamide (BHPO1), N-[3-(benzothiazol-2-yl)-4-hydroxyphenyl]-octanamide (BHPO2), N-[4-(benzothiazol-2-yl)phenyl]-octanamide (BPO) were prepared and their luminescence properties were investigated. These analogues show similar absorption maxima but quite different emission regions due to the existence of an excited-state intramolecular proton transfer (ESIPT) process in BHPO1 and BHPO2. Upon excitation with 365 nm light, BPO, BHPO1 and BHPO2 exhibit bright blue-violet, green and orange emission in aggregated states, respectively which perfectly make up the component elements of white light. By doping these compounds into a polymer matrix at a certain proportion, an emission that lies at the saturated white-light region with CIE chromaticity coordinates of (0.31, 0.32) was obtained. This study provides a flexible and simple fabrication process of a white-light emitting device using three structurally-similar compounds without detrimental energy transfer.