Photophysical And Electroluminescent Properties Of Pyrazolo-pyridine Derivatives

Nowadays, the organic blue light materials and devices are the focuses of the research in OLED. This work focuses on the photophysical properties and the fluorescence quenching of pyrazolo pyridines.The carrier injection and transportation of PAQ5 doped PVK single devices are investigated by studying the current-voltage data. Except for the transition from the injection limited current to space charge limited current (SCLC), there are other two transitions:One is the transition from single injection in the low applied voltage area to the dual injection in the high applied voltage area. The other is the transition for the major injection current mechanism from Richardson-Schotty thermionic emission to Fowler-Nordheim tunneling injection current induced by high electrical field in high applied voltage area.It is the first time to study fluorescence quenching of 4-phenyl-1,3,5,7-tetramethyl-1,7-dihydrodipyrazolo [3,4-b; 4',3'-e] pyridine.The quenching of PAP1 in ethanol solution was measured using HCl as the quencher. The quenching process is found to be a combined dynamic and static quenching process. The dynamic quenching resulted from diffusive collisions between the excited PAP1 and the quencher, i.e. H+ or HCl in this case.The fluorescence quenching of PAP 1 in PVK film in presence of PTS condition was also studied. The absorption and fluorescence spectra was measured and analyzed. It was found that there was a competition between PTS quench PAP1 and PVK fluorescence in PAP1 doped PVK films, with a better quenching of PAP 1.