基于菲并咪唑衍生物的激发态调控及其在蓝光/白光OLED中的应用  

Excited State Regulation Based on Phenanthrimidazole Derivatives and Its Application in Blue/White Light OLED

作　　者：娄敬丽 黎刚刚 王志明 唐本忠 LOU Jingli;LI Ganggang;WANG Zhiming;TANG Benzhong(School of Materials Science&Engineering,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]华南理工大学材料科学与工程学院,广东广州510641

出　　处：《材料研究与应用》2023年第5期773-786,共14页Materials Research and Application

基　　金：国家自然科学基金项目(21975077,51673118);广东省自然科学基金杰出青年基金项目(2022B1515020084);发光材料与器件国家重点实验室(SCUT)自主创新研究项目(Skllmd-2022-01);深圳市分子聚集体功能材料重点实验室(ZDSYS20211021111400001);深圳市科技创新委员会(KQTD20210811090142053);广东省基础与应用基础研究基金(2023B1515040003)。

摘　　要：有机发光二极管的应用已经步入我们的生活领域,但是高效率的蓝色发光材料仍然是限制其效率进一步提高的瓶颈。基于“交叉长短轴”结构模型,以菲并咪唑作为蓝光的构筑基元,设计合成了两个纯蓝光/天蓝光分子NPD和NCNPD。实验和理论计算结果表明:NCNPD分子由于N1位点引入了较强吸电子能力的氰基而表现出了更强的CT态特征,在溶液和薄膜中表现出了比NPD更红的发射和更低的荧光量子产率(PLQY),在此基础上NPD及NCNPD在非掺杂/掺杂器件的最大外量子效率(EQE)分别为1.84%/6.90%和0.76%/6.38%,充分说明在菲并咪唑长轴骨架上引入强CT态组分,以及再配合短轴修饰氰基来增强分子CT态特征,会对分子的光电性能造成不利的影响,凸显出合理调控蓝光材料激发态中的LE/CT态组分的分布和强度的必要性;基于NPD分子开发了一系列高性能的荧磷混合白光OLED,通过调控蓝光层/黄光层的厚度,暖白光及正白光器件的最大EQE达到了23.45%和15.24%;通过调控间隔层的厚度,制备了低滚降、光色稳定的正白光OLED,最高EQE为11.54%,显色指数(CRI)达到了了50。The application of organic light-emitting diodes(OLEDs)has been widely used in our life,but the high efficiency blue light-emitting materials are still the bottleneck restricting their further improvement.Based on the“crossed long-short axis”structure model,we designed and synthesized two pure-blue/sky-blue luminescent molecules,NPD and NCNPD,using phenanthroimidazole(PI)as the building block.Based on the experimental results and theoretical calculation,it is found that the NCNPD exhibits a stronger CT property due to the introduction of an electron-withdrawing cyano group at the N1 position of PI.A s a result,NCNPD shows red shifted emission peaks and lower photoluminescence quantum yields(PLQYs)than NPD in solution and neat film.What’s more,the maximum external quantum efficiencies(EQEs)o f NPD and NCNPD in nondoped/doped OLEDs are 1.84%/6.90%and 0.76%/6.38%,respectively,indicating that introducing strong CT components to the long-axis backbone of PI,combined with the modification of the short-axis skeleton to increase the CT intensity,will negatively affect the optoelectronic performances of molecules,and it is critical to modulate the distribution of the LE/CT component in the excited states of blue-emitting molecules in a reasonable manner.Finally,a series of highperformance hybrid white OLEDs were developed using NPD as a blue emitter.By regulating the thickness of blue-and yellow-emitting layers,the maximum EQEs of the warm-white and pure-white OLEDs reached 23.45%and 15.24%,respectively.O n this basis,by adjusting the thickness of the interlayer,a pure-white OLED with low-efficiency roll-off and stable spectra was fabricated,achieving a maximum EQE of 11.54%with a color rendering index(CRI)exceeding 50.

关 键 词：有机发光二极管 有机蓝光材料 菲并咪唑 交叉长短轴 杂化局域电荷转移 

分 类 号：O482.31[理学—固体物理]