Liu Yulong, Liu Hui, Bai Qing, Du Chunya, Shang Anqi, Jiang Dongyan, Tang Xiangyang, Lu Ping
State Key Laboratory of Supramolecular Structure and Materials, Department of Chemistry, Jilin University, Changchun 130012, China.
Department of Applied Chemistry, Northeast Agricultural University, Harbin 150030, China.
ACS Appl Mater Interfaces. 2020 Apr 8;12(14):16715-16725. doi: 10.1021/acsami.0c01846. Epub 2020 Mar 25.
A family of pyrene[4,5-]imidazole derivatives, PyPA, PyPPA, PyPPAC, and PyPAC, with different excited states are successfully developed. Among them, PyPPA and PyPPAC possess hybridized local and charge-transfer (HLCT) state, endowing them with pure blue fluorescence as well as high quantum yields. The nondoped organic light-emitting diode (OLED) based on PyPPA displays Commission Internationale de L'Eclairage coordinates of (0.14, 0.13) and achieves a maximum external quantum efficiency (EQE) of 8.47%, which are among the highest value reported to date for nondoped blue HLCT OLEDs. The nondoped OLED based on PyPPAC exhibits a maximum luminance of 50,046 cd m located in the blue region with CIE coordinates of (0.15, 0.21) and an EQE of 6.74% even when the luminance reached over 10,000 cd m. In addition, they both reveal ultimate exciton utilizing efficiencies of nearly 100%. The potential of a blue emitter of PyPPA with an HLCT character for application in white OLED (WOLED) is further tested. The efficient two-color hybrid warm WOLED is successfully achieved, which provides the total EQE, power efficiency, and current efficiency of up to 21.19%, 61.46 lm W, and 62.13 cd A, respectively. The nondoped blue OLEDs and hybrid WOLEDs present good color stabilities with low efficiency roll-offs. Our results prove that taking advantage of the HLCT state, nondoped blue OLEDs as well as hybrid WOLEDs with high performance could be realized, which have a promising prospect for the displays and lightings in the future.
成功开发了一系列具有不同激发态的芘[4,5-]咪唑衍生物，即PyPA、PyPPA、PyPPAC和PyPAC。其中，PyPPA和PyPPAC具有杂化局域和电荷转移（HLCT）态，使其具有纯蓝色荧光以及高量子产率。基于PyPPA的非掺杂有机发光二极管（OLED）的国际照明委员会坐标为（0.14, 0.13），最大外量子效率（EQE）达到8.47%，这是迄今为止报道的非掺杂蓝色HLCT OLED的最高值之一。基于PyPPAC的非掺杂OLED在蓝色区域的最大亮度为50,046 cd m，CIE坐标为（0.15, 0.21），即使亮度超过10,000 cd m，EQE仍为6.74%。此外，它们都显示出接近100%的最终激子利用效率。进一步测试了具有HLCT特性的PyPPA作为蓝色发射体在白色OLED（WOLED）中的应用潜力。成功实现了高效的双色混合暖白光WOLED，其总EQE、功率效率和电流效率分别高达21.19%、61.46 lm W和62.13 cd A。非掺杂蓝色OLED和混合WOLED具有良好的颜色稳定性和低效率滚降。我们的结果证明，利用HLCT态可以实现高性能的非掺杂蓝色OLED以及混合WOLED，它们在未来的显示和照明领域具有广阔的前景。
