High-Performance Blue OLEDs Based on Phenanthroimidazole Emitters via Substitutions at the C6- and C9-Positions for Improving Exciton Utilization

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• 作者：Bin Liu ; Yi Yuan ; Dan He ; De-Yue Huang ; Cheng-Yuan Luo ; Ze-Lin Zhu ; Feng Lu ; Prof. Dr. Qing-Xiao Tong and Prof. Dr. Chun-Sing Lee
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：August 16, 2016
• 年：2016
• 卷：22
• 期：34
• 页码：12130-12137
• 全文大小：2825K
• ISSN：1521-3765

文摘

Donor–acceptor (D–A) molecular architecture has been shown to be an effective strategy for obtaining high-performance electroluminescent materials. In this work, two D–A molecules, Ph-BPA-BPI and Py-BPA-BPI, have been synthesized by attaching highly fluorescent phenanthrene or pyrene groups to the C6- and C9-positions of a locally excited-state emitting phenylamine–phenanthroimidazole moiety. Equipped with good physical and hybridized local and charge-transfer properties, both molecules show high performances as blue emitters in nondoped organic light-emitting devices (OLEDs). An OLED using Ph-BPA-BPI as the emitting layer exhibits deep-blue emission with CIE coordinates of (0.15, 0.08), and a maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 4.56 %, 3.60 cd A⁻¹, and 3.66 lm W⁻¹, respectively. On the other hand, a Py-BPA-BPI-based, sky-blue OLED delivers the best results among nondoped OLEDs with CIE_y values of < 0.3 reported so far, for which a very low turn-on voltage of 2.15 V, CIE coordinates of (0.17, 0.29), and maximum CE, PE, and EQE values of 10.9 cd A⁻¹, 10.5 lm W⁻¹, and 5.64 %, were achieved, respectively. More importantly, both devices show little or even no efficiency roll-off and high singlet exciton-utilizing efficiencies of 36.2 % for Ph-BPA-BPI and 39.2 % for Py-BPA-BPI.