(A)Efficient blue-light emitting diodes based on polyfluorene containing bipolar pendant groups (B)A Novel Efficient Blue-Light-Emitter with Improving Electron Injection Property
| Autor: | Mao-Chuan Yuan, 袁茂川 |
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| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 (A)Efficient Blue-Light-Emitting Diodes Based on Polyfluorene Containing Bipolar Pendant Groups Three novel blue-light-emitting copolymers (PFCzs series) with bulky hole-transporting carbazole and/or electron-transporting oxadiazole pendant groups attached at the C-9 position of fluorene have synthesized. The results from photoluminescence and electrochemical measurements reveal that both the side chains and the polyfluorene main chain retain their own electronic characteristics in these copolymers. They also possess high thermal stability and good solubility in common organic solvents. Furthermore, PFECzOXD copolymer with both carbazole and oxadiazole pendant groups demonstrate improved charge injection and balanced charge transport in electroluminescence and maximum external quantum efficiency is 1.09 % at 232 cd/m2 with a current density of 40 mA/cm2. In addition, we blend a red Ir complex (Ir(FPQ)2(acac)) into PFECzOXD copolymer and demonstrate good device performance with maximum external quantum efficiency 8.63 % at 2027 cd/m2 with a current density of 23 mA/cm2. (B)A Novel Efficient Blue-Light-Emitter with Improving Electron Injection Property An efficient blue emitter DPVSBPy was synthesised by incorporating a high affinity bipyridine group at the C-9 substitution of a fluorene-derivatized blue emitter (DPVSBF) without altering the emission properties of the DPVSBF backbone. A double-layer LED device using DPVSBPy as the emitting layer shows a bright blue emission with a low turn-on voltage at 2.5 V and a high brightness of 7196 cd/m2 at a drive voltage of 11.5 V. The maximum external quantum is 1.05 % at 1151 cd/m2 with a current density of of 110 mA/cm2. The improved device performance of DPVSBPy over DPVSBF may be due to better electron injection and transport . |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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