Research Progress on Thermally Activated Delayed Fluorescent Materials

Abstract

Organic light-emitting diodes (OLEDs) have attracted significant attention because of their promise for application in full-colour flat-panel displays and solid-state lighting sources. The ratio of singlet excitons to triplet excitons is 1:3 under electrical excitation. The internal quantum efficiency (IQE) of conventional fluorescent OLEDs is limited to 25% because only singlet excitons are available for light emission. Thermally activated delayed fluorescence (TADF) is a promising way to obtain a high nearly 100% IQE by converting triplet excitons up to the singlet state level by the reverse intersystem crossing (RISC). The key to design TADF materials is to combine a small energy gap (ΔE_ST) between the lowest singlet excited states (S₁) and lowest triplet excited states (T₁) with high photoluminescence quantum efficiency simultaneously. This review summarizes the recent progress in TADF materials, focusing on the design strategies and device performance.

	Service

	Email this article
	Add to my bookshelf
	Add to citation manager
	Email Alert
	RSS
	Articles by authors
	Lu Tianxing
	Li Xianggao
	Xiao Yin
	Wang Shirong

Keywords： electroluminescence； quantum efficiency； donor； acceptor

Received 2015-05-16;

About author:

Cite this article:

Lu Tianxing, Li Xianggao, Xiao Yin, Wang Shirong.Research Progress on Thermally Activated Delayed Fluorescent Materials[J] Chemcial Industry and Engineering, 2017,V34(4): 1-10,32

[1] Segal M, Baldo M A, Holmes R J, et al. Excitonic singlet-triplet ratios in molecular and polymeric organic materials[J]. Physical Review B, 2003, 68(7): 338-344
[2] Rothberg L J, Lovinger A J. Status of and prospects for organic electroluminescence[J]. Journal of Materials Research, 1996, 11(12): 3 174-3 187
[3] Adachi C, Baldo M A, Thompson M E, et al. Nearly 100% internal phosphorescence efficiency in an organic light-emitting device[J]. Journal of Applied Physics, 2001, 90(10): 5 048-5 051
[4] Adachi C. Third-Generation organic electroluminescence materials[J]. Japanese Journal of Applied Physics, 2014, 53(6): 060101. Doi:10.7567/JJAP.53.060101
[5] Smith L H, Wasey J A E, Barnes W L. Light outcoupling efficiency of top-emitting organic light-emitting diodes[J]. Applied Physics Letters, 2004, 84(16): 2 986-2 988
[6] Madigan C F, Lu M H, Sturm J C. Improvement of output coupling efficiency of organic light-emitting diodes by backside substrate modification[J]. Applied Physics Letters, 2000, 76(13): 1 650-1 652
[7] Uoyama H, Goushi K, Shizu K, et al. Highly efficient organic light-emitting diodes from delayed fluorescence[J]. Nature, 2012, 492(7 428): 234-238
[8] Furukawa T, Nakanotani H, Inoue M, et al. Dual enhancement of electroluminescence efficiency and operational stability by rapid upconversion of triplet excitons in OLEDs[J]. Scientific Reports, 2015, 5: 8 429. Doi:10.1038/srep08429
[9] Cho Y J, Yook K S, Lee J Y. High efficiency in a solution-processed thermally activated delayed-fluorescence device using a delayed-fluorescence emitting material with improved solubility[J]. Advanced Materials, 2014, 26(38): 6 642-6 646
[10] Cho Y J, Jeon S K, Chin B D, et al. The design of dual emitting cores for green thermally activated delayed fluorescent materials[J]. Angewandte Chemie International Edition, 2015, 54(17): 5 201-5 204
[11] Li B, Nomura H, Miyazaki H, et al. Dicarbazolyldicyanobenzenes as thermally activated delayed fluorescence emitters: Effect of substitution position on photoluminescent and electroluminescent properties[J]. Chemistry Letters, 2014, 43(3): 319-321
[12] Hung W, Chi L, Chen W, et al. A carbazole-phenylbenzimidazole hybrid bipolar universal host for high efficiency RGB and white PhOLEDs with high chromatic stability[J]. Journal of Materials Chemistry, 2011, 21(48): 19 249-19 256
[13] Lin W, Huang W, Huang M, et al. A bipolar host containing carbazole/dibenzothiophene for efficient solution-processed blue and white phosphorescent OLEDs[J]. Journal of Materials Chemistry C, 2013, 1(41): 6 835-6 841
[14] Nakanotani H, Masui K, Nishide J, et al. Promising operational stability of high-efficiency organic light-emitting diodes based on thermally activated delayed fluorescence[J]. Scientific Reports, 2013, 3: 2 127. Doi:10.1038/srep02127
[15] Komatsu R, Sasabe H, Inomata S, et al. High efficiency solution processed OLEDs using a thermally activated delayed fluorescence emitter[J]. Synthetic Metals, 2015, 202: 165-168
[16] Im Y, Lee J Y. Above 20% external quantum efficiency in thermally activated delayed fluorescence device using furodipyridine-type host materials[J]. Chemistry of Materials, 2014, 26(3): 1 413-1 419
[17] Nishimoto T, Yasuda T, Lee S Y, et al. A six-carbazole-decorated cyclophosphazene as a host with high triplet energy to realize efficient delayed-fluorescence OLEDs[J]. Materials Horizons, 2014, 1(2): 264-269
[18] Kim B S, Lee J Y. Phosphine oxide type bipolar host material for high quantum efficiency in thermally activated delayed fluorescent device[J]. ACS Applied Materials & Interfaces, 2014, 6(11): 8 396-8 400
[19] Gaj M P, Hernandez C F, Zhang Y, et al. Highly efficient organic light-emitting diodes from thermally activated delayed fluorescence using a sulfone-carbazole host material[J]. Organic Electronics, 2015, 16: 109-112
[20] Suzuki Y, Zhang Q, Adachi C. A solution-processable host material of 1,3-bis{3-[3-(9-carbazolyl)phenyl]-9-carbazolyl}benzene and its application in organic light-emitting diodes employing thermally activated delayed fluorescence[J]. Journal of Materials Chemistry C, 2015, 3(8): 1 700-1 706
[21] Kim B S, Lee J Y. Engineering of mixed host for high external quantum efficiency above 25% in green thermally activated delayed fluorescence device[J]. Advanced Functional Materials, 2014, 24(25): 3 970-3 977
[22] Kim B S, Yook K S, Lee J Y. Above 20% external quantum efficiency in novel hybrid white organic light-emitting diodes having green thermally activated delayed fluorescent emitter[J]. Scientific Reports, 2014, 4: 6 019. Doi:10.1038/srep06019
[23] Kim B S, Lee J Y. Interlayer free hybrid white organic light-emitting diodes with red/blue phosphorescent emitters and a green thermally activated delayed fluorescent emitter[J]. Organic Electronics, 2015, 21: 100-105
[24] Nishide J, Nakanotani H, Hiraga Y, et al. High-Efficiency white organic light-emitting diodes using thermally activated delayed fluorescence[J]. Applied Physics Letters, 2014, 104(23): 233 304
[25] Lee S Y, Yasuda T, Nomura H, et al. High-Efficiency organic light-emitting diodes utilizing thermally activated delayed fluorescence from triazine-based donor-acceptor hybrid molecules[J]. Applied Physics Letters, 2012, 101(9): 1 585
[26] 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]. Applied Physics Letters, 2011, 98(8): 42. Doi:10.1063/1.3558906
[27] Sato K, Shizu K, Yoshimura K, et al. Organic luminescent molecule with energetically equivalent singlet and triplet excited states for organic light-emitting diodes[J]. Physical Review Letters, 2013, 110(24): 247 401-247 401
[28] Serevi??ius T, Nakagawa T, Kuo M C, et al. Enhanced electroluminescence based on thermally activated delayed fluorescence from a carbazole-triazine derivative[J]. Physical Chemistry Chemical Physics, 2013, 15(38): 15 850-15 855
[29] Shizu K, Uejima M, Nomura H, et al. Enhanced electroluminescence from a thermally activated delayed-fluorescence emitter by suppressing nonradiative decay[J]. Physical Review Applied, 2015, 3(1): 014 001.Doi:10.1103/PhysRevApplied.3.014001
[30] Kim M, Jeon S K, Hwang S H, et al. Stable blue thermally activated delayed fluorescent organic light-emitting diodes with three times longer lifetime than phosphorescent organic light-emitting diodes[J]. Advanced Materials, 2015, 27(15): 2 515-2 520
[31] Tanaka H, Shizu K, Miyazakiab H, et al. Efficient green thermally activated delayed fluorescence (TADF) from a phenoxazine-triphenyltriazine (PXZ-TRZ) derivative[J]. Chemical Communications, 2012, 48(93): 11 392-11 394
[32] Tanaka H, Shizu K, Nakanotani H, et al. Dual intramolecular charge-transfer fluorescence derived from a phenothiazine-triphenyltriazine derivative[J]. The Journal of Physical Chemistry C, 2014, 118(29): 15 985-15 994
[33] Tanaka H, Shizu K, Nakanotani H, et al. Twisted intramolecular charge transfer state for long-wavelength thermally activated delayed fluorescence[J]. Chemistry of Materials, 2013, 25(18): 3 766-3 771
[34] Nakagawa T, Ku S Y, Wong K T, et al. Electroluminescence based on thermally activated delayed fluorescence generated by a spirobifluorene donor-acceptor structure[J]. Chemical Communications, 2012, 48(77): 9 580-9 582
[35] Méhes G, Nomura H, Zhang Q, et al. Enhanced electroluminescence efficiency in a spiro-acridine derivative through thermally activated delayed fluorescence[J]. Angewandte Chemie International Edition, 2012, 51(45): 11 311-11 315
[36] Nasu K, Nakagawa T, Nomura H, et al. A highly luminescent spiro-anthracenone-based organic light-emitting diode exhibiting thermally activated delayed fluorescence[J]. Chemical Communications, 2013, 49(88): 10 385-10 387
[37] Ohkuma H, Nakagawa T, Shizu K, et al. Thermally activated delayed fluorescence from a spiro-diazafluorene derivative[J]. Chemistry Letters, 2014, 43(7): 1 017-1 019
[38] Zhang Q, Li J, Shizu K, et al. Design of efficient thermally activated delayed fluorescence materials for pure blue organic light emitting diodes[J]. Journal of the American Chemical Society, 2012, 134(36): 14 706-14 709
[39] Wu S, Aonuma M, Zhang Q, et al. High-Efficiency deep-blue organic light-emitting diodes based on a thermally activated delayed fluorescence emitter[J]. Journal of Materials Chemistry C, 2013, 2(3): 421-424
[40] Zhang Q, Li B, Huang S, et al. Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence[J]. Nature Photonics, 2014, 8(4): 326-332
[41] Takahashi T, Shizu K, Yasuda T, et al. Donor-Acceptor-structured 1,4-diazatriphenylene derivatives exhibiting thermally activated delayed fluorescence: Design and synthesis, photophysical properties and OLED characteristics[J]. Science and Technology of Advanced Materials, 2014, 15(3): 034202. Doi:10.1088/1468-6996/15/3/034202
[42] Lee J, Chopra N, Eom S H, et al. Effects of triplet energies and transporting properties of carrier transporting materials on blue phosphorescent organic light emitting devices[J]. Applied Physics Letters, 2008, 93: 123306. Doi: 10.1063/1.2978235
[43] Wang Q, Ding J, Ma D, et al. Harvesting excitons via two parallel channels for efficient white organic LEDs with nearly 100% internal quantum efficiency: Fabrication and emission-mechanism analysis[J]. Advanced Functional Materials, 2009, 19(1): 84-95
[44] Lee J, Shizu K, Tanaka H, et al. Oxadiazole-and triazole-based highly-efficient thermally activated delayed fluorescence emitters for organic light-emitting diodes[J]. Journal of Materials Chemistry C, 2013, 1(30): 4 599-4 604
[45] Tanaka H, Shizu K, Lee J, et al. Effect of atom substitution in chalcogenodiazole-containing thermally activated delayed fluorescence emitters on radiationless transition[J]. The Journal of Physical Chemistry C, 2015, 119: 2 948-2 955