[1] [1] Tang C W, Vanslyke S A. Organic electroluminescent diodes. Applied Physics Letters, 1987, 51(12): 913–915

[2] [2] Xie F M, An Z D, Xie M, Li Y Q, Zhang G H, Zou S J, Chen L, Chen J D, Cheng T, Tang J X. Tert-butyl substituted hetero-donor TADF compounds for efficient solution-processed non-doped blue OLEDs. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2020, 8(17): 5769–5776

[3] [3] Kim H J, Godumala M, Kim S K, Yoon J, Kim C Y, Park H, Kwon J H, Cho M J, Choi D H. Color-tunable boron-based emitters exhibiting aggregation-induced emission and thermally activated delayed fluorescence for efficient solution-processable nondoped deep-blue to sky-blue OLEDs. Advanced Optical Materials, 2020, 8 (14): 1902175

[4] [4] Matsuo K, Yasuda T. Blue thermally activated delayed fluorescence emitters incorporating acridan analogues with heavy group 14 elements for high-efficiency doped and non-doped OLEDs. Chemical Science (Cambridge), 2019, 10(46): 10687–10697

[5] [5] Yi C L, Ko C L, Yeh T C, Chen C Y, Chen Y S, Chen D G, Chou P T, HungWY,Wong K T. Harnessing a new co-host system and low concentration of new TADF emitters equipped with trifluoromethyland cyano-substituted benzene as core for high-efficiency blue OLEDs. ACS Applied Materials & Interfaces, 2020, 12(2): 2724– 2732

[6] [6] Wang Q, Tian Q S, Zhang Y L, Tang X, Liao L S. High-efficiency organic light-emitting diodes with exciplex hosts. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2019, 7(37): 11329–11360

[7] [7] Zhang Q S, Li B, Huang S P, Nomura H, Tanaka H, Adachi C. Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence. Nature Photonics, 2014, 8(4): 326– 332

[8] [8] Zhang Q, Tsang D, Kuwabara H, Hatae Y, Li B, Takahashi T, Lee S Y, Yasuda T, Adachi C. Nearly 100% internal quantum efficiency in undoped electroluminescent devices employing pure organic emitters. Advanced Materials, 2015, 27(12): 2096–2100

[9] [9] uan C, Fan C, Wei Y, Han F, Huang W, Xu H. Optimizing the intralayer and interlayer compatibility for high-efficiency blue thermally activated delayed fluorescence diodes. Scientific Reports, 2016, 6(1): 19904

[10] [10] Yang H, Liang Q Q, Han C M, Zhang J, Xu H. A posphanthrene oxide host with close sphere packing for ultralow-voltage-driven efficient blue thermally activated delayed fluorescence diodes. Advanced Materials, 2017, 29(38): 1700553

[11] [11] Zhang Z, Ding D X, Wei Y, Zhang J, Han C M, Xu H. Excited-state engineering of universal ambipolar hosts for highly efficient blue phosphorescence and thermally activated delayed fluorescence organic light-emitting diodes. Chemical Engineering Journal, 2020, 382: 122485

[12] [12] Gao F F, Du R M, Jiao F X, Lu G, Zhang J, Han CM, Xu H. A novel bridge-ring phosphine oxide host 5,10-[1,2]benzenophosphanthrene 5,10-dioxide for ultralow-voltage-driven blue thermally activated delayed fluorescence diodes. Advanced Optical Materials, 2020, 8 (13): 2000052

[13] [13] Zhang J, Ding D, Wei Y, Han F, Xu H, Huang W. Multiphosphineoxide hosts for ultralow-voltage-driven true-blue thermally activated delayed fluorescence diodes with external quantum efficiency beyond 20%. Advanced Materials, 2016, 28(3): 479–485

[14] [14] Cao X S, Chen Z X, Gong S L, Pan K, Zhou C J, Huang T, Chai D Y, Zhan Q, Li N Q, Zou Y, Liu H, Yang C L. Designing versatile sulfoximine as accepting unit to regulate the photophysical properties of TADF emitters towards high-performance OLEDs. Chemical Engineering Journal, 2020, 399: 125648

[15] [15] Wu Z, Liu Y, Yu L, Zhao C, Yang D, Qiao X, Chen J, Yang C, Kleemann H, Leo K, Ma D. Strategic-tuning of radiative excitons for efficient and stable fluorescent white organic light-emitting diodes. Nature Communications, 2019, 10(1): 2380

[16] [16] Zhao J, Wang Z J, Wang R, Chi Z G, Yu J S. Hybrid white organic light-emitting devices consisting of a non-doped thermally activated delayed fluorescent emitter and an ultrathin phosphorescent emitter. Journal of Luminescence, 2017, 184: 287–292

[17] [17] Yang J, Zhao S L, Song D D, Xu Z, Qiao B, Wang P, Wei P. Highly efficient solution processed blue thermally activated delayed fluorescent organic light-emitting devices with a mixed hole injection layer. Spectroscopy and Spectral Analysis, 2020, 40(4): 1028–1033

[18] [18] Yang J, Song D, Zhao S, Qiao B, Xu Z, Wang P, Wei P. Highly efficient and bright blue organic light-emitting devices based on solvent engineered, solution-processed thermally activated delayed fluorescent emission layer. Organic Electronics, 2019, 71: 1–6

[19] [19] Kido J, Hongawa K, Okuyama K, Nagai K. Bright blue electroluminescence from poly(N-vinylcarbazole). Applied Physics Letters, 1993, 63(19): 2627–2629

[20] [20] Hladka I, Lytvyn R, Volyniuk D, Gudeika D, Grazulevicius J V. Wshaped bipolar derivatives of carbazole and oxadiazole with high triplet energies for electroluminescent devices. Dyes and Pigments, 2018, 149: 812–821

[21] [21] Zhang Z H, Jiang W, Ban X X, Yang M, Ye S H, Huang B, Sun YM. Solution-processed efficient deep-blue fluorescent organic lightemitting diodes based on novel 9,10-diphenyl-anthracene derivatives. RSC Advances, 2015, 5(38): 29708–29717

[22] [22] Jeltsch K F, Lupa G, Weitz R T. Materials depth distribution and degradation of a FIrpic based solution-processed blue OLED. Organic Electronics, 2015, 26: 365–370

[23] [23] Jankus V, Abdullah K, Griffiths G C, Al-Attar H, Zheng Y H, Bryce M R, Monkman A P. The role of exciplex states in phosphorescent OLEDs with poly(vinylcarbazole) (PVK) host. Organic Electronics, 2015, 20: 97–102

[24] [24] Girotto E, Pereira A, Arantes C, Cremona M, Bortoluzzi A J, Salla C A M, Bechtold I H, Gallardo H. Efficient terbium complex based on a novel pyrazolone derivative ligand used in solution-processed OLEDs. Journal of Luminescence, 2019, 208: 57–62

[25] [25] Zhang Q, Zhang X W, Wei B. Highly efficient ultraviolet organic light-emitting diodes and interface study using impedance spectroscopy. Optik (Stuttgart), 2015, 126(18): 1595–1597

[26] [26] Si C F, Chen G, Guo K P, Pan S H, Peng C Y, Wei B. Enhanced performance in inverted organic light-emitting diodes using Li ion doped ZnO cathode buffer layer. Molecular Crystals and Liquid Crystals (Philadelphia, Pa.), 2017, 651(1): 118–125

[27] [27] Moon J, Cho H, Maeng M J, Choi K, Nguyen D T, Han J H, Shin J W, Kwon B H, Lee J, Cho S, Lee J I, Park Y, Lee J S, Cho N S. Mechanistic understanding of improved performance of graphene cathode inverted organic light-emitting diodes by photoemission and impedance spectroscopy. ACS Applied Materials & Interfaces, 2018, 10(31): 26456–26464

[28] [28] Voitsekhovskii A V, Nesmelov S N, Dzyadukh S M, Kopylova T N, Degtyarenko K M. Impedance characterization of organic lightemitting structures with thermally activated delayed fluorescence. Physica Status Solidi A, Applications and Materials Science, 2020, 217(6): 1900847

[29] [29] Gao M, Lee T, Burn P L, Mark A E, Pivrikas A, Shaw P E. Revealing the interplay between charge transport, luminescence efficiency, and morphology in organic light-emitting diode blends. Advanced Functional Materials, 2020, 30(9): 1907942.