Synthesis and Characterization of triazole-Containing Biphenyl Derivatives and Application in Blue Phosphorescent Organic Light Emitting Diodes
Date Issued
2011
Date
2011
Author(s)
Chen, Nai-Jing
Abstract
In this thesis, 2,2’-bis(1,5-diphenyl-1,2,4-triazol)biphenyl derivatives were successfully prepared. These compounds possess scissor-like conformations which were evidenced by using the spectroscopic and electrochemical methods, as well as by X-ray crystallography. The presence of the ample conformational variations influences their photoluminescence and morphological stability: (1) the scissor-like structures would breakdown the intramolecular pi-conjugation of the molecule, (2) The non-coplanar structure would also hamper the intermolecular stacking, prohibiting the compounds from crystallization and therefore increasing the thermal stability of their amorphous film structure. Two reduction waves by cyclic voltammetry were observed for each compound, indicating that both of the triazole units could be smoothly reduced. Although the reduction potential difference is small, the presence of the difference clearly indicates that through-space electronic interactions are present between the two triazole units. The electronic effects arising from the substituent of terminal phenyl units on the triazole reductions are small. These results suggest that the anionic sites are mainly localized at the triazole units. Delocalization of the negative charges onto the terminal phenyl rings is almost negligible. Organic light emitting diodes (OLED) with 2,2’-bis(1,5-diphenyl-1,2,4-triazol)biphenyl as the host matrix for FIrpic were successfully prepared. Under the best conditions, the OLED exhibited luminance efficiency of 44.3 cd/A with the maximum brightness of 2123 cd/m2.
Subjects
1, 2, 4-trazole
host
biphenyl
emitting diodes
Type
thesis
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