Effect of functional group substitution on the photoluminescence and electroluminescence of pyrazoline derivatives

Two derivatives of pyrazoline with different substitutional groups were synthesized. The effects of substitution on their photoluminescence (PL) and eletroluminescence were studied. It was observed that the fluorescence quantum yield of the compound PD2 with a methoxy substitutional group is larger than that of the compound PD1, which has an N,N-dimethlyamino substitutional group. On the other hand, when these compounds were used as dopants in blue-light-emitting organic electroluminescent devices with a configuration of 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/m² at a current density of about 420 mA/cm².