Photoluminescence and electroluminescence properties of coumarin-urea/poly(N-vinylcarbazole) blends

The photoluminescence (PL) properties of a novel coumarin derivative (DCDU) in solution state and in poly(N-vinylcarbazole) (PVK) matrix were investigated. The single-layer electroluminescence (EL) devices fabricated from the DCDU/PVK blends showed the emission peak varying from 445 nm to 472 nm with the different dye doping ratio. When 2,5-bis(5′-tert-butyl-2-benzoxazoly)thiophene (BBOT) was used as an electron transport layer, the ITO/(2 wt.% DCDU+PVK)/BBOT/A1 device displayed the improved characteristics with the low turn-on voltage at 6.3 V, a maximum luminance of 730 cd/m2 and an external quantum efficiency of 0.8%.