OPV and multiphenyl for organic light emitting diodes application
Date Issued
2006
Date
2006
Author(s)
Kuo, Chao-Hui
DOI
en-US
Abstract
The essay were discussed the organic light emitting diodes. In the chapter 2 and chapter were discussed the theories and equipments of PLED. The chapter 3 and chapter 4 were discussed the polyurethane effect in the PLED devices. A novel family of hole-transport polyurethanes (PUs) has been developed. The PUs were prepared from the condensation
polymerization of isophorone diisocyanate (IPDI) with
(E,E)-1,4-bis(2-hydroxystyryl)benzene, an oligo p-phenylene-(E)-vinylene (OPV) unit, and various amounts of 2,5-bis(4-hydroxyphenyl)-1,3,4-oxadiazole (OXD), as well as with
4-tert-butyl phenol as the terminal group. The PUs demonstrates superior properties that were concluded on the basis of the improved current injection in the corresponding hole-only device. When compared to the control device, the current efficiency was improved 2.37 times. The maximum brightness increased to 14900 cd/m2 in comparison to that of 5780 cd/m2 for the control device. The performance of the OLED devices was fine-tuned by adjusting the combination of the OPV and OXD units to reach electron-hole balanced conditions. The maximum current efficiency increased to 4.12 cd/A at 5.5 V when the PU layer of OPV:OXD ) 67:33 was used. In the chapter 5 and chapter 6, a series of PPV system polymers was synthesized and the relationships between chemical structure design and thermal stability、optical properties、electro-chemical properties or device performance are discussed. At first, a series of PPV-Fluorene system copolymers was synthesized and discussed into three aspects (1) Molecular Weight Effect in PLED. (2) End Group Effect in PLED. (3)
Copolymer and tricopolymer comparability in PLED. By doing research in these three systems, we interiorize the application of PPV-Fluorene system luminescent polymers in
Polymer light emitting diode (PLED). It is found that the molecular weight mainly affects the film quality in device manufacturing when molecular weight increasing to a certain degree.End group is also an important improvement factor for luminescent properties of device, especially for applying triphenylamine group. On the other hand, based on luminescence conversion mechanism, a high efficiency PLED based on yellowish-white light CIE 1931 (0.423, 0.429) is successfully fabricated by simple spin-coating process. The device has external quantum efficiency of 3% and brightness of 400cd/m2. By combining dibromobenzo thiadiazole group into PPV-Fluorene system copolymers as tricopolymers, a high brightness green light PLED device is also successfully fabricated. The device has external quantum
efficiency of 2.3% and brightness of 4250cd/m2. In the chapter 7, series of the co-polymers with huge hinder 4-pentaphenylphenyl-phenyl group as side chain were been synthesized by Suzuki coupling process. The co-polymers are introducing four different kinds of repeat unit when polymerized including carbazole, fluorene, benzothiadiazole and oligophenylenevinylene (OPV) with their own optical properties, respectively. Therefore, these co-polymers are not only to be the emitting layer by themselves but also be the host role in phosphorescence material when doping Ir(ppy)3 as guest and PBD in the PLED device. The optical performance of the co-polymers and device are measured, PL spectra, electroluminescence, UV-vis, turn-on voltage, efficiency are included in our research.
Subjects
有機發光二極體
Organic light emitting diodes
polymer e,itting
Type
thesis
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