The effect of functional group substitution on the photoluminescence and electroluminescence of pyrazoline derivatives

Two derivatives of pyrazoline with different substitutional groups were syn thesized. The effects of substitution on their photoluminescence (PL) and e letroluminescence were studied. It was observed that the fluorescence quant um yield of the compound PD2 with a methoxy substitutional group is larger than that of the compound PD1, which has an N,N-dimethlyamino substitutiona l group. On the other hand, when these compounds were used as dopants in bl ue-light-emitting organic electroluminescent devices with a configuration o f indium tin oxide (ITO)/TPD/TPBI:2% PD1 or PD2/TPBI/Mg:Ag, the device with PD1 as the dopant was more efficient than that with PD2 despite the higher fluorescence quantum yield of PD2. The PD1-doped device emitted blue light , which peaked at around 487 nm with a luminance of 1224 cd/m(2) at a curre nt density of about 420 mA/cm(2). (C) 2000 Elsevier Science S.A. All rights reserved.