Rational design of perfectly oriented thermally activated delayed fluorescence emitter for efficient red electroluminescence

Zhang, Xuan; Huang, Yu‐Hsin; Gong, Shaolong; Yin, Xuguang; Lee, Wei‐Kai; Xiao, Xiao; Zhang, Yu; Zeng, Weixuan; Lu, Chen‐Han; Lee, Chang-Cheng; Dong, Xiu‐Qin; Zhong, Cheng; Wu, Chung‐Chih; Yang, Chuluo

doi:10.1007/s40843-020-1501-1

Cited by 32 publications

(16 citation statements)

References 41 publications

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“…A similar molecule with a highly horizontal TDM orientation, the red emitter PhNAI‐PMSBA, was recently reported by Zeng et al. [ 75 ] PhNAI‐PMSBA is the longest molecule in our database ( x E = 34.4 Å), it is highly linear ( L = 0.63), and it also has a high MW (986 Da). Additionally, when used in the mCPCN host, PhNAI‐PMSBA achieved the highest x E / x H value in this database (2.57).…”

Section: Results From Meta‐analysis Of Literature Data and Dft Modelingsupporting

confidence: 74%

“…The figure was made using data from 53 separate reports that include EQE max and emitter orientation data on 124 materials systems. [ 20,22–24,37–85 ] While there is no correlation between EQE max and anisotropy across all data, it is clear that the highest efficiency in TADF‐ and non‐TADF‐based systems, respectively, is reached at low anisotropy factors.…”

Section: Introductionmentioning

confidence: 92%

“…First, in the many studies that have reported improved horizontal alignment of molecules with higher aspect ratios compared to other molecules with similar structures, claims on linearity and planarity are often evoked but rarely quantified. [ 20,24,38–41,45–49,52–54,57,60,65–67,75,93,112 ] As we mentioned above, the real impact of an increase in the aspect ratio of molecules is difficult to assess because the studies are often based on the addition of moieties to reference molecules. Therefore, the reported increases in the linearity or planarity of the molecules are accompanied by increases in MW.…”

Section: Recent Demonstrations Of Horizontal Orientation In New Tadf and Deep‐blue Fluorescent Emittersmentioning

confidence: 99%

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Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

et al. 2021

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In organic light‐emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass‐transition temperature (Tg) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state‐of‐the‐art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum‐processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta‐analysis of 203 published emitter systems is conducted and combined with density‐functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host–guest systems with low‐MW emitters, orientation is mostly influenced by the host Tg, whereas the length and MW of the emitter become more relevant for systems involving higher‐MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.

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Section: Results From Meta‐analysis Of Literature Data and Dft Modelingsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 92%

Section: Recent Demonstrations Of Horizontal Orientation In New Tadf and Deep‐blue Fluorescent Emittersmentioning

confidence: 99%

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Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

et al. 2021

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“…S1, the PL decay curves of both exciplexes contained a prompt fluorescence and a delayed fluorescence. In addition, the delayed components of the two exciplexes were evidently stronger than that of pure 3Cz-o-TRz, indicating the more efficient RISC process of these exciplexes, which would benefit the exciton utilization in the OLEDs [34]. Accordingly, we further measured the PL quantum yields The key performances of these OLEDs are illustrated in Fig.…”

Section: Resultsmentioning

confidence: 93%

Novel donor-spacer-acceptor compound as the multifunctional component of exciplexes for efficient organic light-emitting diodes

et al. 2021

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By connecting tercarbazole (3Cz) and triphenyltriazine (TRz) units with a diphenyl ether group, we designed and synthesized a new donor-spacer-acceptor structure molecule 9'-(4-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenoxy) phenyl)-9'H-9,3':6',9"-tercarbazole (3Cz-o-TRz) as the multifunctional component of exciplex emitters. As expected, the intermolecular charge-transfer transition is dominant for 3Cz-o-TRz because of the space-enough and conjugation-forbidden linkage of the diphenyl ether group, increasing the intrinsic characteristics of the 3Cz and TRz moieties in its single-molecule state. Accordingly, three common electron acceptors (4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PyMPm), 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2methylpyrimidine (B4PyMPm), and (1,3,5-triazine-2,4,6-triyl) tris(benzene-3,1-diyl)tris(diphenylphosphineoxide) (PO-T2T)) and three common electron donors (4,4'-(cyclohexane-1,1-diyl)bis(N,N-di-p-tolylaniline) (TAPC), tris(4-(10H-phenoxazin-10-yl)phenyl)amine (TPA-PXZ), and N1-phenyl-N4, N4-bis(4-(phenyl(m-tolyl)amino)phenyl)-N1-(m-tolyl)benzene-1,4-diamine (m-MTDATA)) were chosen to construct six exciplex emitters with 3Cz-o-TRz. In the organic light-emitting diodes (OLEDs), the emission spectra of these exciplex emitters could be gradually modulated from 510 to 590 nm. In addition, TAPC:3Cz-o-TRz-and 3Cz-o-TRz:PO-T2T-based OLEDs achieved desirable performance with maximum external quantum efficiencies (EQEs) around 12%. Moreover, a simple tandem OLED containing TAPC:3Cz-o-TRz and 3Czo-TRz:PO-T2T emitters realized optimal performance with an ultralow turn-on voltage of 2.4 V and a maximum EQE of 14.1%. These results indicate the great potential of the donorspacer-acceptor structure compounds in developing exciplex emitters.

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“…Following this concept, we have developed several efficient blue, orange-red and red TADF emitters with high Θ//'s of up to 95%. [8][9][10][11] The multicolor OLEDs based on our TADF emitters have demonstrated outstanding device performance with over 25% EQE for blue, over 30% EQE for orange-red, and nearly 28% EQE for red TADF OLEDs.…”

Section: Developing Tadf Emitters With High θ//'Smentioning

confidence: 96%

28‐1: Invited Paper: Efficient Thermally Activated Delayed Fluorescence Emitters with Preferentially Horizontal Dipole Orientations

Gong

Yang

2021

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Rational design of perfectly oriented thermally activated delayed fluorescence emitter for efficient red electroluminescence

Cited by 32 publications

References 41 publications

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

Novel donor-spacer-acceptor compound as the multifunctional component of exciplexes for efficient organic light-emitting diodes

28‐1: Invited Paper: Efficient Thermally Activated Delayed Fluorescence Emitters with Preferentially Horizontal Dipole Orientations

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