EFFICIENT BLUE LUMINESCENCE OF A CONJUGATED POLYMER EXCIPLEX

Efficient blue light emission is observed from a bilayer thin film of poly(p-phenylene-2,6-benzobis(oxazole)) (PBO) and tris(p-tolyl)amine (TTA) dispersed in the matrix of Bisphenol A polycarbonate. PBO thin films emit green light with the emission peak at 500 nm. The luminescence of PBO/TTA bilayer thin films (15-50 nm) has a peak at 474 nm and a factor of 3.4-4.2 increase in fluorescence quantum efficiency relative to PBO thin films. The steady state and time-resolved photoluminescence results suggest that the emission from PBO/TTA bilayer films originates from (PBO-TTA(+))* exciplex formation due to photoinduced electron transfer. The present results demonstrate that conjugated polymer exciplexes represent a new approach to blue luminescence as well as a means to enhance the solid state fluorescence quantum efficiency of conjugated polymers.