High-Performance Hole-Transport Polyurethanes for Light-Emitting Diodes Applications

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• 作者：Chao-Hui Kuo ; Kang-Chun Peng ; Li-Chung Kuo ; Kuei-Hui Yang ; Jiun-Haw Lee ; Man-kit Leung ; Kuo-Huang Hsieh
• 刊名：Chemistry of Materials
• 出版年：2006
• 出版时间：August 22, 2006
• 年：2006
• 卷：18
• 期：17
• 页码：4121 - 4129
• 全文大小：145K
• 年卷期：v.18,no.17(August 22, 2006)
• ISSN：1520-5002

文摘

A novel family of hole-transport polyurethanes (PUs) has been developed. The PUs were preparedfrom 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. ThePUs demonstrates superior properties that were concluded on the basis of the improved current injectionin the corresponding hole-only device. The OLED device with the OPV-PU interfacial layer inserted inITO/PEDOT:PSS(20 nm)/PU(30 nm)/-NPB(10 nm)/Bebq₂(20 nm)/Ca(10 nm)/Ag(100 nm) has a dramaticvoltage reduction of 2.5 V under the current density of 100 mA/cm². When compared to the controldevice, the current efficiency was improved 2.37 times. The maximum brightness increased to 14900cd/m² in comparison to that of 5780 cd/m² for the control device. The performance of the OLED deviceswas fine-tuned by adjusting the combination of the OPV and OXD units to reach electron-hole balancedconditions. 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.