Blue organic light emitting devices(OLEDs) with Alq, PBD, BBOT or F OXD as the electron transport layer were fabricated by a high vacuum multisource type organic molecular deposition system. The effect of various electron transport layers on the performances of OLED was studied. The result indicates that the performances of devices with electron transport layer added between emitter and cathode are increased greatly. It is found that device: ITO/TPD/PPCP/Alq/Al is optimal in structure compared with other devices. Its turn on voltage is 4 V. Its maximal brightness is 2 000 cd/m 2 and its maximal efficiency is 0.36 lm/W.
The band gap( E g) and HOMO level of pyrazoline derivative were obtained by UV Vis absorption spectra and electrochemical cyclic voltammetry methods. The effect of the molecular structure of pyrazoline on the energy band structure was investigated. It was indicated that the HOMO level changed from -5.56 eV to -5.10 eV while the LUMO level changed from -2 68 eV to -2.36 eV with different substituents in pyrazoline derivatives. The results obtained showed that the energy band structure of pyrazoline derivatives could be adjusted through changing the molecular structure. [WT5HZ]
