图1 传统荧光、磷光及TADF材料的发光机理。
Published:05 December 2022,
Received:14 July 2022,
Revised:03 August 2022
Scan QR Code
Cite this article
Pyrimidine can be used as a common acceptor for the construction of D-A type thermally activated delayed fluorescent(TADF) materials. Its strong electron absorption characteristics and flexible substitution effect are advantageous to the formation of diversified molecular structures, which lends probability to realize efficient organic electroluminescence. In recent years, important progress has been made in the molecular structure design based on pyrimidine acceptor. The research direction has transformed from symmetrical molecules dominated by D-A-D type to asymmetric molecules gradually. Quinazoline is a new acceptor of TADF materials with fused bicyclic structure of benzene and pyrimidine rings, which shows good potential as a result of extended conjugate plane. Through the reasonable molecular modification, it can improve the luminescence performance of the device effectively. In this review, we summarize the research progress of thermally activated delayed fluorescent materials based on pyrimidine and its derivative quinazoline acceptors briefly with molecular structure, photophysical properties and device performances, and look forward to the broad development prospect of TADF materials based on quinazoline.
自1987年邓青云发明有机发光二极管(OLED)以来[
如
图1 传统荧光、磷光及TADF材料的发光机理。
Fig.1 Luminescent mechanism of fluorescence, phosphorescence and TADF materials.
高效OLED是人们一直以来追求的目标,对基于TADF材料的OLED而言,器件的外量子效率不仅与材料本身的发光效率有关,还受到延迟荧光效率的影响。反系间窜越速率(kRISC)是表征材料延迟荧光效率的重要参数,其大小与最低单重态-三重态能级差ΔEST和环境温度T直接相关,其关系表现为:ΔEST越小,温度T越高,相应的kRISC值就越高。所以,为实现高效的反系间窜越过程,TADF体系要求材料的最低单重态(S1)和三重态(T1)能级尽可能接近,即具有较小的ΔEST值。
通过合理的有机分子结构设计,充分分离最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO),降低HOMO-LUMO重叠积分,理论上可以有效减小TADF分子的ΔEST值。因此,TADF分子常见的设计思路是构建具有高度扭曲结构的给体-受体型(D-A型)分子骨架[
其中,嘧啶是TADF分子构建中广泛应用的受体之一。与TADF材料中最早报道的受体三嗪相比,含有两个氮原子的嘧啶电子接受能力适中,在蓝光TADF分子的开发中极具潜力;同时嘧啶的不对称结构使其相比于吡嗪可变性更强,为有机分子设计提供了更多的可能。嘧啶受体的优异特性引起了研究人员的广泛关注,基于其构建的D-A型TADF分子表现出良好的器件性能,并由此进一步衍生出了共轭平面更大的喹唑啉系列受体。本文总结了基于嘧啶及其衍生物受体的TADF发光材料研究进展,深入讨论其分子结构设计策略、光物理性质以及器件性能之间的联系,从而为高效TADF材料的设计合成提供参考。
嘧啶(PM)是一种双氮六元杂环化合物,与苯和吡啶相比,它具有强吸电子特性,取代更为多样化。作为目前应用最为广泛的二嗪,嘧啶在芳香基取代条件下化学稳定性良好,易于通过结构修饰来调整分子的发射特性[
图2 基于嘧啶受体的TADF分子设计策略
Fig.2 Molecular design strategy of TADF materials based on pyrimidine acceptor
D-A-D型对称结构是以嘧啶作为受体核心,两个完全相同的给体单元分别占据4和6位,由苯基单元作为连接给体与受体的π桥,从而形成的稳定U型结构。利用扭曲的π-共轭体系,这些分子通常可以获得较小的ΔEST值和高PLQY。在嘧啶受体的2位通过进行简单的分子修饰,连接的一些小基团(如甲基和苯基)能够实现对TADF材料光电性能的调控[
2016年,Sasabe和Kido等首次报道了具有D-A-D型对称结构的嘧啶基TADF发光分子[
分子类型 | λEL/nm | CIE(x, y) | EQEmax/% | CEmax/(cd·A-1) | PEmax/(lm·W-1) | 参考文献 |
---|---|---|---|---|---|---|
Ac⁃HPM | — | (0.21, 0.44) | 20.9 | 60.3 | 54.7 |
[ |
Ac⁃PPM | 495 | (0.21, 0.44) | 19.0 | 52.8 | 49.2 |
[ |
Ac⁃MPM | 487 | (0.19, 0.37) | 24.5 | 61.6 | 54.9 |
[ |
PXZPM | 528 | (0.33, 0.57) | 19.9 | 65.4 | 60.1 |
[ |
PXZMePM | — | (0.30, 0.56) | 22.2 | 71.3 | 68.4 |
[ |
PXZPhPM | — | (0.32, 0.57) | 24.6 | 80.0 | 73.7 |
[ |
Ac⁃NPM | 480 | (0.17, 0.29) | 14.4 | 27.8 | 30.5 |
[ |
分子类型 | λEL/nm | CIE(x, y) | EQEmax/% | CEmax/(cd·A-1) | PEmax/(lm·W-1) | 参考文献 |
---|---|---|---|---|---|---|
PXZ⁃PPM | 539 | (0.36, 0.58) | 25.1 | 89.4 | 111.0 |
[ |
ClPPM | 546 | (0.40, 0.55) | 25.3 | 68.9 | 67.7 |
[ |
BrPPM | 544 | (0.39, 0.56) | 23.6 | 66.2 | 61.2 |
[ |
PXZPyPM | 528 | (0.33, 0.58) | 33.9 | 113.5 | 118.9 |
[ |
PXZTAZPM | 528 | (0.33, 0.58) | 30.1 | 101.3 | 106.1 |
[ |
2DPAc⁃MPM | 468 | (0.16, 0.21) | 19.0 | 32.0 | 27.9 |
[ |
2DPAc⁃PPM | 472 | (0.16, 0.24) | 20.8 | 38.2 | 31.5 |
[ |
2SPAc⁃HPM | 487 | (0.18, 0.34) | 25.6 | 57.5 | 51.6 |
[ |
2SPAc⁃MPM | 479 | (0.17, 0.29) | 24.3 | 50.0 | 42.5 |
[ |
2SPAc⁃PPM | 484 | (0.18, 0.32) | 31.5 | 68.8 | 56.9 |
[ |
m⁃2SPAc⁃PPM | 499 | — | 17.6 | 43.1 | 38.2 |
[ |
o⁃2SPAc⁃PPM | 512 | — | 24.8 | 73.1 | 67.6 |
[ |
p,o⁃SPAc⁃PPM | 500 | (0.23, 0.43) | 23.2 | 62.2 | 55.8 |
[ |
p,m⁃SPAc⁃PPM | 486 | (0.20, 0.36) | 25.1 | 58.2 | 50.7 |
[ |
m,o⁃SPAc⁃PPM | 500 | (0.24, 0.43) | 23.3 | 61.9 | 54.0 |
[ |
Ac⁃1MHPM | 477 | (0.17, 0.28) | 24.0 | 46.0 | 45.1 |
[ |
Ac⁃2MHPM | 477 | (0.17, 0.27) | 19.8 | 36.9 | 35.8 |
[ |
Ac⁃3MHPM | 451 | (0.16, 0.15) | 17.8 | 19.9 | 19.6 |
[ |
PXZ⁃PYR | 536 | (0.35, 0.56) | 27.9 | — | 84.1 |
[ |
PXZ⁃muPYR | 529 | (0.32, 0.55) | 29.1 | — | 74.1 |
[ |
PXZ⁃mdPYR | 514 | (0.27, 0.49) | 27.5 | — | 75.2 |
[ |
PXZ⁃2mPYR | 502 | (0.23, 0.42) | 26.3 | — | 53.3 |
[ |
MFAc⁃PPM | 470 | (0.16, 0.23) | 20.4 | 41.7 | 37.2 |
[ |
MXAc⁃PPM | 462 | (0.16, 0.20) | 12.2 | 22.7 | 18.8 |
[ |
MFAc⁃PM | 469 | (0.16, 0.21) | 17.1 | 34.3 | 31.7 |
[ |
MXAc⁃PM | 460 | (0.16, 0.19) | 14.3 | 25.0 | 20.7 |
[ |
Ac⁃PM | 458 | (0.15, 0.15) | 11.4 | 18.9 | 16.5 |
[ |
Ac⁃46DPPM | — | (0.16, 0.21) | 11.8 | 18.3 | 19.7 |
[ |
Ac⁃26DPPM | — | (0.18, 0.33) | 18.6 | 39.6 | 43.5 |
[ |
CzAc⁃26DPPM | — | (0.21, 0.38) | 22.8 | 53.9 | 59.2 |
[ |
为改善效率滚降问题,同年,杨楚罗课题组选
用给电子能力更强的吩噁嗪作为给体单元合成了三种绿光TADF分子(
图3 基于嘧啶受体的D-A-D型分子结构
Fig.3 D-A-D type molecular structure based on pyrimidine acceptors
将电子受体卤化是缩短TADF发光分子的延迟荧光寿命、改善器件效率滚降的另一可行策略。杨楚罗等以绿光分子PXZPM为基础,将卤素原子Cl和Br分别引入嘧啶受体,开发了两种新型TADF发光分子,即ClPPM和BrPPM(
2020年,杨楚罗团队再次改进PXZPM分子结构,他们在嘧啶受体的2位分别连接苯基吡啶和三苯基-三嗪取代基,得到了两种新型分子[
基于嘧啶类受体的TADF材料目前已取得不错的研究进展,特别是对于绿光OLED成果显著。相较之下,由于器件效率、色纯度以及稳定性等问题的制约,高效蓝光TADF材料的开发仍是当前亟待解决的一大难题。Yasuda等以9,9-二苯基-9,10-二氢吖啶(DPAc)作为给体,合成了两种高效纯蓝TADF发光分子:2DPAc-MPM和2DPAc-PPM(
更进一步,我们将相同的给体SPAc分别与作为π桥的苯基的邻位和间位相连,合成了m-2SPAc-PPM和o-2SPAc-PPM两种发光分子(
最近,我们在已有研究的基础上,通过给体与苯基相连位置的不同组合,设计合成了三种发光分子,统称为X-SPAc-PPM(
除了对嘧啶受体2位的取代基进行改进和优化,Sasabe和Kido等也尝试对共轭苯环进行分子修饰[
Serevičius等基于嘧啶受体核开发了一系列TADF分子,通过在苯基片段上插入不同数量的甲基来改变其刚性结构[
由于吩噁嗪的平面性使其可以承担更大的空间位阻,在进一步的研究中,该课题组选用吩噁嗪给体,继续利用甲基作为空间位阻调节剂,从而实现对分子结构调控。结果表明,含有正甲基片段的嘧啶衍生物PXZ-mdPYR具有较大的ΔEST值和较低的kRISC,而基于甲基调控的结构优化,使得间甲基修饰的嘧啶衍生物PXZ-muPYR的kRISC从0.7×106 s-1提高到6.5×106 s-1。基于PXZ-muPYR的TADF器件获得了29.1%的高EQE值[
具有D-A-D对称构型的嘧啶类化合物发光性能优良,发展前景广阔,由此引发了研究者探索其分子结构与光电特性之间关系的极大热情,并尝试开发更多的可能构型以实现性能突破。D-A构型是基于嘧啶受体的TADF材料的另一常见设计策略,不同于D-A-D型分子具有两个给体单元,此类分子通常只在嘧啶受体上连接一个给体。相比于D-A-D型,D-A型发光分子呈现出较弱的CT特性,从而更容易实现蓝移,为高效蓝光TADF分子设计提供了一种可行方案[
Yasuda等在嘧啶的2位分别连接螺-吖啶(MPAc)、吖啶(Ac)、螺-氧杂蒽(MXAc)三种不同的大体积给体,嘧啶的4,6位则尝试由苯基取代,合成了一系列具有扭曲构型的D-A型TADF分子(
图4 基于嘧啶受体的D-A型分子结构
Fig.4 D-A type molecular structure based on pyrimidine acceptors
不同于简单对称结构,在嘧啶的4位或6位不对称连接单一给体单元,将使得嘧啶受体的取代关系更加多样化,有助于深入探究分子结构与发光性能的关系。在Ac-PM的基础上,Sasabe和Kido等对具有不对称结构的嘧啶类TADF化合物进行了研究[
喹唑啉具有苯并嘧啶的稠环结构,是一种平面芳香杂环化合物,多用于生物医药领域[
图5 喹唑啉单元结构示意图
Fig.5 Illustration of quinazoline unit structure
目前喹唑啉及其衍生物在OLED中应用的研究还很缺乏,在已有报道中多用作主体材料。2016年,王子兴等以喹唑啉为中心,设计合成了一系列分子,并将其作为OLED的主体材料,相应的红色磷光OLED获得了19.2%的最大外量子效率[
2019年,本课题组首次引入喹唑啉单元(PQ)这一简单结构作为高效受体,设计合成了一类全新的D-A型TADF材料[
图6 基于喹唑啉受体的TADF分子结构
Fig.6 Molecular structure of TADF based on quinazoline acceptors
分子类型 | λEL/nm | CIE/(x, y) | EQEmax/% | CEmax/(cd·A-1) | PEmax/(lm·W-1) | 参考文献 |
---|---|---|---|---|---|---|
4HQ⁃PXZ | 511 | (0.25, 0.54) | 20.2 | 61.4 | 60.3 |
[ |
4PQ⁃PXZ | 518 | (0.28, 0.57) | 20.5 | 65.6 | 64.4 |
[ |
2HQ⁃PXZ | 538 | (0.36, 0.57) | 16.0 | 42.9 | 42.1 |
[ |
2PQ⁃PXZ | 538 | (0.36, 0.56) | 17.1 | 55.7 | 54.7 |
[ |
2PQ⁃Cz | 445 | (0.15, 0.01) | 2.17 | — | — |
[ |
4PQ⁃Cz | 436 | (0.16, 0.08) | 1.33 | — | — |
[ |
24PQ⁃Cz | 448 | (0.15, 0.11) | 2.64 | — | — |
[ |
4PQ⁃NH | 495 | (0.35, 0.34) | 3 | 5.4 | 5.14 |
[ |
2PQ⁃PTZ | 570 | (0.46, 0.52) | 25.0 | 72.2 | 71.9 |
[ |
4PQ⁃PTZ | 550 | (0.69, 0.54) | 18.4 | 59.3 | 62.0 |
[ |
PQ⁃DitCz | 562 | — | 0.5 | ~0.5 | ~0.3 |
[ |
2DPyPh⁃Qz | 555 | (0.43, 0.55) | 27.5 | 89.9 | 96.5 |
[ |
实现具有高色纯度的稳定蓝光器件,关键在于通过适当的有机分子设计,尽可能减小光谱的半峰宽(FWHM),提升窄带发射能力。2020年,我们使用喹唑啉受体实现了最大波长不超过450 nm的高色纯度稳定深蓝光发射[
有机单分子白光OLED在实际照明应用中极具潜力。早在2013年,张红雨等就将喹唑啉分别与咔唑和二苯胺通过苯桥连接,得到4PQ-Cz和4PQ-NH两种D⁃A型蓝光分子,通过与控制酸质子化后的橙光发射相结合,实现了白色光致发光,为白光OLED的获得提供了一种新颖简单的方法,但尚未过多地关注效率问题[
2020年,我们通过连接喹唑啉受体和吩噻嗪给体,设计了两个分子2PQ-PTZ和4PQ-PTZ[
图7 2PQ-PTZ和4PQ-PTZ构象的晶体结构。 (a)2PQ-PTZ中准轴向“ax”构象(Ⅰ)和准赤道“eq”构象(Ⅱ)的晶体结构;(b)4PQ-PTZ准赤道“eq(1)”构象(Ⅲ)和“eq(2)” (Ⅳ)构象的晶体结构;(c)2PQ-PTZ和4PQ-PTZ不同扭转角下的柔性势能表面扫描[
Fig.7 Crystal structures of 2PQ-PTZ and 4PQ-PTZ conformers. H atoms have been omitted for clarity. (a)Crystal structure of “ax” (Ⅰ) and“eq” (Ⅱ) conformers of 2PQ-PTZ. (b)Crystal structure of “eq(1)” (Ⅲ) and “eq(2)” (Ⅳ) conformers of 4PQ-PTZ. (c)Flexible potential surface energy scanning of 2PQ-PTZ and 4PQ-PTZ at different twisted angles[
图8 (a)基于2PQ-PTZ的白光OLED在1 000 cd·m-2处的EL光谱(插图为OLED运行时的照片);(b)基于2PQ-PTZ的白光OLED的电流密度和亮度随电压(J⁃V⁃L)变化特性;(c)基于2PQ-PTZ和4PQ-PTZ的黄光OLED的EL光谱;(d)黄光OLED的J⁃V⁃L变化特性[
Fig.8 (a)EL spectrum of 2PQ-PTZ-based white OLED at 1 000 cd·m-2(the inset is the photo of OLED under operation). (b)Current density and luminance versus voltage(J⁃V⁃L) characteristics of 2PQ-PTZ-based white OLED. (c)EL spectra of 2PQ-PTZ and 4PQ-PTZ-based yellow OLEDs. (d)J⁃V⁃L characteristics of the yellow OLEDs[
此外,Grazulevicius等基于喹唑啉受体开发了一种白光激基复合物OLED。他们分别以叔丁基修饰的咔唑、二甲基吖啶和吩噻嗪作为给体部分,合成了三种化合物,通过DFT理论计算和实验,探究了其光物理性能、电化学性能和热力学性质。所合成的3,6-二叔丁基咔唑取代的喹唑啉基化合物在固体掺杂膜中能够与受体PO-T2T形成天蓝色发光激基复合物,也能够与给体m-MTDATA形成橙色发光激基复合物。基于上述激基复合系统,制得的白光OLED器件的外量子效率为0.5%,最大亮度为3 030 cd·m-2[
由于单重态能级较低,基于喹唑啉-吩噁嗪的发光分子呈现绿色到绿黄色的电致发光。为优化发射偶极子水平取向,提高OLED器件效率,杨楚罗课题组通过进一步的分子修饰,在2PQ-PXZ的基础上,通过连接两个吡啶环来延伸受体平面,合成了绿光TADF分子2DPyPh-Qz,在掺杂薄膜中实现了79%的高水平偶极比和96%的高PLQY[
经过三十多年的发展,有机电致发光技术逐渐成熟,OLED市场前景广阔,当前已在显示照明领域占有一席之地,并呈现出良好的发展趋势。热激活延迟荧光材料具有高效率、低成本的优异性能,有望取代传统磷光材料,在未来实现大规模的商业应用。合理设计D-A型分子结构是实现高效TADF材料的有效途径。嘧啶是一类性能良好的常见受体,其取代的多样性为有机分子结构设计提供了更多可能,近年来受到了研究人员的广泛关注。目前对于以嘧啶为受体核的D-A-D型对称TADF分子的研究日趋成熟,通过调节给体单元和取代基种类及位置,在蓝光、绿光OLED器件方面获得了令人满意的出色性能;而对于不对称结构,取代类型则更加多样化,有助于进一步调控分子的光电特性。基于嘧啶受体的TADF材料表现出良好的研究价值,但在实际亮度下的长期稳定性及高亮度下的效率衰减等问题仍面临挑战,有待开发新型分子以实现器件性能的突破。
喹唑啉是由嘧啶衍生出来的一种新型TADF受体,苯并嘧啶的稠环结构使其具有比嘧啶更长的共轭长度和更大的共轭平面,进而表现出吸电子能力的增强。以此为基础开发的喹唑啉系列TADF发光分子,通过不同种类给体的连接,可以达到调控材料光物理性能的目的。基于喹唑啉类化合物的TADF OLED器件性能优异,外量子效率均超过20%,在高效蓝光以及白光OLED的开发方面极具发展潜力。另外,取代基的位置和种类对材料的发光性能影响显著,基于喹唑啉的不对称结构和不同的取代位点,通过特定位置取代基团的变化来进行适当的分子修饰,可有效改善材料的ICT特性,实现器件光色、色纯度及效率水平的提升。目前对基于喹唑啉受体的TADF材料发光性能的研究仍然较为缺乏,具有很大的研究空间。我们相信,随着对喹唑啉类受体研究的发展和深入,材料及器件性能有望得到进一步提升,从而在未来形成一类重要的材料体系,推动高效稳定的TADF材料在OLED领域的商业化进程。
本文专家审稿意见及作者回复内容的下载地址:http://cjl.lightpublishing.cn/thesisDetails#10.37188/
CJL.20220273.
TANG C W, VANSLYKE S A. Organic electroluminescent diodes [J]. Appl. Phys. Lett., 1987, 51(12): 913-915. doi: 10.1063/1.98799 [Baidu Scholar]
ENDO A, SATO K, YOSHIMURA K, et al. Efficient up-conversion of triplet excitons into a singlet state and its application for organic light emitting diodes [J]. Appl. Phys. Lett., 2011, 98(8): 083302. [Baidu Scholar]
UOYAMA H, GOUSHI K, SHIZU K, et al. Highly efficient organic light-emitting diodes from delayed fluorescence [J]. Nature, 2012, 492(7428): 234-238. doi: 10.1038/nature11687 [Baidu Scholar]
刘婷婷, 李淑红, 王文军, 等. 基于器件结构提高TADF-OLED器件的发光性能 [J]. 发光学报, 2020, 41(1): 77-85. doi: 10.3788/fgxb20204101.0077 [Baidu Scholar]
LIU T T, LI S H, WANG W J, et al. Enhanced luminescent properties of TADF-OLEDs based on device structures [J]. Chin. J. Lumin., 2020, 41(1): 77-85. (in Chinese). doi: 10.3788/fgxb20204101.0077 [Baidu Scholar]
卢伶, 张祥, 赵青华. 热激活延迟荧光材料在有机电致发光器件中的研究进展 [J]. 材料导报, 2019, 33(15): 2589-2601. doi: 10.11896/cldb.19010093 [Baidu Scholar]
LU L, ZHANG X, ZHAO Q H. Research progress on thermal activated delayed fluorescence materials for organic light-emitting diodes [J]. Mater. Rep., 2019, 33(15): 2589-2601. (in Chinese). doi: 10.11896/cldb.19010093 [Baidu Scholar]
LI C L, DUAN R H, LIANG B Y, et al. Deep-red to near-infrared thermally activated delayed fluorescence in organic solid films and electroluminescent devices [J]. Angew. Chem. Int. Ed., 2017, 56(38): 11525-11529. [Baidu Scholar]
NAVEEN K R, CP K P, BRAVEENTH R, et al. Molecular design strategy for orange red thermally activated delayed fluorescence emitters in organic light-emitting diodes (OLEDs) [J]. Chem. Eur. J., 2022, 28(12): e202103532. doi: 10.1002/chem.202281261 [Baidu Scholar]
WANG S P, YAN X J, CHENG Z, et al. Highly efficient near-infrared delayed fluorescence organic light emitting diodes using a phenanthrene-based charge-transfer compound [J]. Angew. Chem. Int. Ed., 2015, 54(44): 13068-13072. [Baidu Scholar]
YAO L, YANG B, MA Y G. Progress in next-generation organic electroluminescent materials: material design beyond exciton statistics [J]. Sci. China Chem., 2014, 57(3): 335-345. [Baidu Scholar]
曹云锋, 李旭萍, 卢建军. 基于热活化延迟荧光双发射的有机电子给体-受体型材料研究进展 [J]. 发光学报, 2021, 42(9): 1386-1395. doi: 10.37188/CJL.20210181 [Baidu Scholar]
CAO Y F, LI X P, LU J J. Research progress of thermally activated delayed fluorescence materials with dual-emission based on donor-acceptor system [J]. Chin. J. Lumin., 2021, 42(9): 1386-1395. (in Chinese). doi: 10.37188/CJL.20210181 [Baidu Scholar]
马志华, 马荣荣, 董文月, 等. 树枝状热活化延迟荧光材料研究进展 [J]. 发光学报, 2021, 42(7): 904-916. doi: 10.37188/CJL.20210099 [Baidu Scholar]
MA Z H, MA R R, DONG W Y, et al. Recent advances on thermally activated delayed fluorescence dendrimers [J]. Chin. J. Lumin., 2021, 42(7): 904-916. (in Chinese). doi: 10.37188/CJL.20210099 [Baidu Scholar]
KATO Y, SASABE H, HAYASAKA Y, et al. A sky blue thermally activated delayed fluorescence emitter to achieve efficient white light emission through in situ metal complex formation [J]. J. Mater. Chem. C, 2019, 7(11): 3146-3149. [Baidu Scholar]
KOMATSU R, SASABE H, SEINO Y, et al. Light-blue thermally activated delayed fluorescent emitters realizing a high external quantum efficiency of 25% and unprecedented low drive voltages in OLEDs [J]. J. Mater. Chem. C, 2016, 4(12): 2274-2278. [Baidu Scholar]
ZHANG Q S, LI J, SHIZU K, et al. Design of efficient thermally activated delayed fluorescence materials for pure blue organic light emitting diodes [J]. J. Am. Chem. Soc., 2012, 134(36): 14706-14709. [Baidu Scholar]
RAJAMALLI P, SENTHILKUMAR N, GANDEEPAN P, et al. A method for reducing the singlet-triplet energy gaps of TADF materials for improving the blue OLED efficiency [J]. ACS Appl. Mater. Interfaces, 2016, 8(40): 27026-27034. doi: 10.1021/acsami.6b10678 [Baidu Scholar]
ACHELLE S, HODÉE M, MASSUE J, et al. Diazine-based thermally activated delayed fluorescence chromophores [J]. Dyes Pigm., 2022, 200: 110157. [Baidu Scholar]
YU L, YANG C L. Multipath exciton harvesting in diazine-based luminescent materials and their applications for organic light-emitting diodes [J]. J. Mater. Chem. C, 2021, 9(48): 17265-17286. doi: 10.1039/D1TC04397H [Baidu Scholar]
WU K L, ZHANG T, ZHAN L S, et al. Optimizing optoelectronic properties of pyrimidine-based TADF emitters by changing the substituent for organic light-emitting diodes with external quantum efficiency close to 25% and slow efficiency roll-off [J]. Chem. Eur. J., 2016, 22(31): 10860-10866. [Baidu Scholar]
KOMATSU R, SASABE H, NAKAO K, et al. Unlocking the potential of pyrimidine conjugate emitters to realize high‐performance organic light‐emitting devices [J]. Adv. Opt. Mater., 2017, 5(2): 1600675. [Baidu Scholar]
XIANG Y P, ZHAO Y B, XU N, et al. Halogen-induced internal heavy-atom effect shortening the emissive lifetime and improving the fluorescence efficiency of thermally activated delayed fluorescence emitters [J]. J. Mater. Chem. C, 2017, 5(46): 12204-12210. doi: 10.1039/C7TC04181K [Baidu Scholar]
XIANG Y P, LI P, GONG S L, et al. Acceptor plane expansion enhances horizontal orientation of thermally activated delayed fluorescence emitters [J]. Sci. Adv., 2020, 6(41): eaba7855. doi: 10.1126/sciadv.aba7855 [Baidu Scholar]
PARK I S, LEE J, YASUDA T. High-performance blue organic light-emitting diodes with 20% external electroluminescence quantum efficiency based on pyrimidine-containing thermally activated delayed fluorescence emitters [J]. J. Mater. Chem. C, 2016, 4(34): 7911-7916. [Baidu Scholar]
LI B W, LI Z Y, HU T P, et al. Highly efficient blue organic light-emitting diodes from pyrimidine-based thermally activated delayed fluorescence emitters [J]. J. Mater. Chem. C, 2018, 6(9): 2351-2359. [Baidu Scholar]
LI B W, LI Z Y, WEI X F, et al. Molecular engineering of thermally activated delayed fluorescence emitters to concurrently achieve high performance and reduced efficiency roll-off in organic light-emitting diodes [J]. J. Mater. Chem. C, 2019, 7(32): 9966-9974. [Baidu Scholar]
LI B W, LI Z Y, SONG X A, et al. Pyrimidine-based thermally activated delayed fluorescent materials with unique asymmetry for highly-efficient organic light-emitting diodes [J]. Dyes Pigm., 2022, 203: 110373. [Baidu Scholar]
KOMATSU R, OHSAWA T, SASABE H, et al. Manipulating the electronic excited state energies of pyrimidine-based thermally activated delayed fluorescence emitters to realize efficient deep-blue emission [J]. ACS Appl. Mater. Interfaces, 2017, 9(5): 4742-4749. [Baidu Scholar]
SEREVIČIUS T, SKAISGIRIS R, DODONOVA J, et al. Emission wavelength dependence on the rISC rate in TADF compounds with large conformational disorder [J]. Chem. Commun., 2019, 55(13): 1975-1978. [Baidu Scholar]
PARK I S, KOMIYAMA H, YASUDA T. Pyrimidine-based twisted donor-acceptor delayed fluorescence molecules: a new universal platform for highly efficient blue electroluminescence [J]. Chem. Sci., 2017, 8(2): 953-960. [Baidu Scholar]
NAKAO K, SASABE H, KOMATSU R, et al. Significant enhancement of blue OLED performances through molecular engineering of pyrimidine-based emitter [J]. Adv. Opt. Mater, 2017, 5(6): 1600843. [Baidu Scholar]
SEREVIČIUS T, SKAISGIRIS R, DODONOVA J, et al. Minimization of solid-state conformational disorder in donor-acceptor TADF compounds [J]. Phys. Chem. Chem. Phys., 2020, 22(1): 265-272. [Baidu Scholar]
SEREVIČIUS T, SKAISGIRIS R, DODONOVA J, et al. Achieving submicrosecond thermally activated delayed fluorescence lifetime and highly efficient electroluminescence by fine-tuning of the phenoxazine-pyrimidine structure [J]. ACS Appl. Mater. Interfaces, 2020, 12(9): 10727-10736. [Baidu Scholar]
SEREVIČIUS T, BUČIŪNAS T, BUCEVIČIUS J, et al. Room temperature phosphorescence vs. thermally activated delayed fluorescence in carbazole⁃pyrimidine cored compounds [J]. J. Mater. Chem. C, 2018, 6(41): 11128-11136. [Baidu Scholar]
KOMATSU R, SASABE H, KIDO J. Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices [J]. J. Photonics Energy, 2018, 8(3): 032108. [Baidu Scholar]
HELD F E, GURYEV A A, FRÖHLICH T, et al. Facile access to potent antiviral quinazoline heterocycles with fluorescence properties via merging metal-free domino reactions [J]. Nat. Commun., 2017, 8: 15071. [Baidu Scholar]
MOTOYAMA M, DOAN T H, HIBNER-KULICKA P, et al. Synthesis and structure-photophysics evaluation of 2-N-Amino-quinazolines: small molecule fluorophores for solution and solid state [J]. Chem. Asian J., 2021, 16(15): 2087-2099. [Baidu Scholar]
ZHANG Z, XIE J W, WANG H B, et al. Synthesis, photophysical and optoelectronic properties of quinazoline-centered dyes and their applications in organic light-emitting diodes [J]. Dyes Pigm., 2016, 125: 299-308. [Baidu Scholar]
KIM S M, YUN J H, HAN S H, et al. A design strategy of bipolar host materials for more than 30 times extended lifetime in phosphorescent organic light-emitting diodes using benzocarbazole and quinazoline [J]. J. Mater. Chem. C, 2017, 5(35): 9072-9079. [Baidu Scholar]
KIM D Y, KANG J S, LEE S E, et al. Blue organic light-emitting diodes based on fluorene-bridged quinazoline and quinoxaline derivatives [J]. Luminescence, 2017, 32(7): 1180-1185. [Baidu Scholar]
LI B W, WANG Z H, SU S J, et al. Quinazoline‐based thermally activated delayed fluorecence for high‐performance OLEDs with external quantum efficiencies exceeding 20% [J]. Adv. Opt. Mater., 2019, 7(9): 1801496. [Baidu Scholar]
LI B W, SONG X A, JIANG X, et al. Stable deep blue organic light emitting diodes with CIE of y < 0.10 based on quinazoline and carbazole units [J]. Chin. Chem. Lett., 2020, 31(5): 1188-1192. [Baidu Scholar]
LIU D, ZHANG Z Y, ZHANG H Y, et al. A novel approach towards white photoluminescence and electroluminescence by controlled protonation of a blue fluorophore [J]. Chem. Commun., 2013, 49(85): 10001-10003. [Baidu Scholar]
LI B W, LI Z Y, GUO F Y, et al. Realizing efficient single organic molecular white light-emitting diodes from conformational isomerization of quinazoline-based emitters [J]. ACS Appl. Mater. Interfaces, 2020, 12(12): 14233-14243. [Baidu Scholar]
KERUCKIENE R, VEKTERYTE S, URBONAS E, et al. Synthesis and properties of quinazoline-based versatile exciplex-forming compounds [J]. Beilstein J. Org. Chem., 2020, 16: 1142-1153. [Baidu Scholar]
LI P, XIANG Y P, GONG S L, et al. Quinazoline-based thermally activated delayed fluorescence emitters for high-performance organic light-emitting diodes with external quantum efficiencies about 28% [J]. J. Mater. Chem. C, 2021, 9(37): 12633-12641. doi: 10.1039/D1TC02633J [Baidu Scholar]
555
Views
356
Downloads
1
CSCD
Related Articles
Related Author
Related Institution