Polynorbornene Copolymer with Side-Chain Iridium(III) Emitters and Carbazole Hosts: A Single Emissive Layer Material for Highly Efficient Electrophosphorescent Devices

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• 作者：Jun Ha Park ; Tae-Wook Koh ; Jin Chung ; Sung Hoon Park ; Maengsun Eo ; Youngkyu Do ; Seunghyup Yoo ; Min Hyung Lee
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：February 12, 2013
• 年：2013
• 卷：46
• 期：3
• 页码：674-682
• 全文大小：539K
• 年卷期：v.46,no.3(February 12, 2013)
• ISSN：1520-5835

文摘

Vinyl addition copolymerization of norbornene monomers using a Pd(II) catalyst in combination with 1-octene chain transfer agent efficiently produces well-defined soluble polynorbornene copolymers bearing side-chain (CN)₂Ir(OO) emitters (CN = 2-(4,6-difluorophenyl)-pyridine (M₃); 2-phenyl-pyridine (M₄); 2-(benzo[b]thiophen-2-yl)-pyridine (M₅), OO = acetylacetonato) and 9,9鈥?(1,3-phenylene)bis-9H-carbazole (mCP) or 9,9鈥?(1,1鈥?biphenyl)-4,4鈥?diylbis-9H-carbazole (CBP) host moieties (M₁ and M₂). The catalytic system provides high-molecular-weight copolymers (M_w = 151鈥?00鈥?57鈥?00 g/mol) with a controlled incorporation of monomers. All copolymers possess high thermal stability with high decomposition (T_d5 > 400 掳C) and glass transition temperatures (T_g > 330 掳C). Among the solution-processed devices fabricated based on a single emissive layer comprising the blue-, green-, and red-phosphorescent copolymers (PBn, PGn, and PRn, n = 1鈥?) with various concentrations of emitters (1.7鈥?3.9 mol %-Ir), the devices based on PB4 (10.5 mol %-Ir), PG2 (5.3 mol %-Ir), and PR4 (13.9 mol %-Ir) display the best performances with maximum power efficiencies of 12.9, 25.6, and 3.3 lm/W and maximum external quantum efficiencies of 8.8, 13.3, and 5.1%, respectively, for each color. These results correspond to almost double the efficiencies of the corresponding doped polymer systems and are outstanding among the polymeric rivals reported thus far.