A Phosphorescent OLED with an Efficiency Roll-Off Lower than 1% at 10,000 cd/m2 Achieved by Reducing the Carrier Mobility of the Donors in an Exciplex Co-host System
學年 110
學期 2
出版（發表）日期 2022-03-09
作品名稱 A Phosphorescent OLED with an Efficiency Roll-Off Lower than 1% at 10,000 cd/m2 Achieved by Reducing the Carrier Mobility of the Donors in an Exciplex Co-host System
作品名稱（其他語言）
著者 Chun-Hao Chiu; Nurul Ridho Al Amin ; Jia-Xun Xie; Chih-Chien Lee; Dian Luo; Sajal Biring; Kevin Sutanto; Shun-Wei Liu; Chih-Hsin Chen
單位
出版者
著錄名稱、卷期、頁數 Journal of Materials Chemistry C 10, p.4955-4964
摘要 9,9′-Diphenyl-9H,9′H-3,3′-bicarbazole (BCzPh)-based molecules have been applied as donors in an exciplex co-host system in OLEDs to achieve high device performance. In this work, to investigate the effect of charge mobility of the donor on the performance of OLEDs using an exciplex co-host system, we synthesized two bipolar BCzPh analogs, i.e., BCzPh-pimi and BCzPh-mimi, by introducing 1-phenyl-1H-benzimidazole to the para- and meta-positions of the phenyl ring of BCzPh. The ΔEST values of BCzPh-pimi and BCzPh-mimi are 0.60 eV and 0.59 eV, respectively. In contrast, the ΔEST values of the exciplex formed by BCzPh-pimi and BCzPh-mimi with an electron acceptor, i.e., B3PyMPM, are 0.26 eV and 0.19 eV, respectively. In addition, the photoluminescence (PL) decay lifetimes of BCzPh-pimi and BCzPh-mimi increase remarkably from 5.39 ns and 9.46 ns to 247.79 ns and 263.21 ns, respectively, when mixed with B3PyMPM. The OLEDs fabricated by using BCzPh-pimi with B3PyMPM as an exciplex co-host for a green phosphorescence emitter, i.e., Ir(ppy)2(acac), exhibited a maximum external quantum efficiency (EQE) of 22.31%. Notably, the BCzPh-pimi-based device showed an extremely low efficiency roll-off. Its EQE was retained at 22.16% even at a high luminance of 10[thin space (1/6-em)]000 cd m−2, corresponding to the efficiency roll-off of only 0.67%. Such an extremely low efficiency roll-off of the device can be attributed to the reduced hole mobility of BCzPh-pimi resulting from the electron-withdrawing benzimidazole moiety in the molecular structure of BCzPh, which improves balance in charge recombination in the exciplex co-host system of OLED devices at high applied voltages.
關鍵字
語言 zh_TW
ISSN 2050-7526
期刊性質 國外
收錄於 SCI
產學合作
通訊作者
審稿制度 是
國別 GBR
公開徵稿
出版型式 ,電子版,紙本
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機構典藏連結 ( http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/123400 )