Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off

Wu, Tien-Lin; Huang, Min‐Jie; Lin, Chih-Chun; Huang, Pei-Yun; Chou, Tsu-Yu; Chen-Cheng, Ren-Wu; Lin, Hao‐Wu; Liu, Rai‐Shung; Cheng, Chien-Hong

doi:10.1038/s41566-018-0112-9

Cited by 720 publications

(450 citation statements)

References 39 publications

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“…Finally, D-π-A triarylboranes with small singlet-triplet gaps are already proving useful in thermally activated delayed fluorescence (TADF) based materials. [42,[86][87][88][89][90][91][92][93][94][95][96][97][98] The use of trifluoromethylated aryl groups in three coordinate boron compounds for optical applications provides a very efficient tool to fine tune properties. Consequently, it is of the utmost importance to understand the electronic properties of these systems in detail.…”

Section: Resultsmentioning

confidence: 99%

Insights into the Optical Properties of Triarylboranes with Strongly Electron‐Accepting Bis(fluoromesityl)boryl Groups: when Theory Meets Experiment

et al. 2019

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The photophysical properties (absorption, fluorescence and phosphorescence) of a series of triarylboranes of the form 4‐D−C6H4−B(Ar)2 (D=tBu or NPh2; Ar=mesityl (Mes) or 2,4,6‐tris(trifluoromethylphenyl (Fmes)) were analyzed theoretically using state‐of‐the‐art DFT and TD‐DFT methods. Simulated emission spectra and computed decay rate constants are in very good agreement with the experimental data. Unrestricted electronic computations including vibronic contributions explain the unusual optical behavior of 4‐tBu−C6H4−B(Fmes)2 2, which shows both fluorescence and phosphorescence at nearly identical energies (at 77 K in a frozen glass). Analysis of the main normal modes responsible for the phosphorescence vibrational fine structure indicates that the bulky tert‐butyl group tethered to the phenyl ring is strongly involved. Interestingly, in THF solvent, the computed energies of the singlet and triplet excited states are very similar for compound 2 only, which may explain why 2 shows phosphorescence in contrast to the other members of the series.

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Section: Resultsmentioning

confidence: 99%

Insights into the Optical Properties of Triarylboranes with Strongly Electron‐Accepting Bis(fluoromesityl)boryl Groups: when Theory Meets Experiment

et al. 2019

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“…If this molecule is linkedw ith the propera cceptor, the as-formed D-A compounds mighte xhibit TADF character. [32][33][34][35][36] In this work, we have synthesized and characterizedf our compounds, 2-5 (Scheme 1). The cyano-modified triarylboron acceptorp resentsastrong electron-acceptinga bility,a sw ell as steric bulkiness,b eing similar to thet riarylboron group.…”

Section: Introductionmentioning

confidence: 99%

Electron‐Rich Twistacene‐Modified Arylboron Donor–Acceptor Systems: Synthesis, Photophysics, and Electroluminescence with Hot Exciton Response

Jin

Han

Tian

et al. 2020

Chemistry A European J

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A series of twistacene‐functionalized donor (D)‐π‐acceptor (A) derivatives (2–5) have been designed and synthesized, in which twistacene can be regarded as a promising platform for electron‐rich systems for fluorescence emitters. The connecting modes and various acceptors are also examined to investigate the effect of structural changes on the photophysical, electrochemical, and thermal properties. The strong electron‐withdrawing capability of the arylboron‐modified benzonitrile unit can effectively separate the HOMO and LUMO energy levels of 4/5, which is beneficial for the formation of thermally activated delayed fluorescence (TADF) molecules. Cyan and orange organic light‐emitting diodes based on 4 and 5 exhibit promising electroluminescence with a maximum brightness of 7643 cd m−2 for device‐4 and 14871 cd m−2 for device‐5.

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“…Thermally activated delayed fluorescence (TADF) emitters,following the conventional fluorescent [1,2] and phosphorescent ones, [3,4] are now recognized as third-generation electroluminescent materials for organic light-emitting diodes (OLEDs). [5][6][7][8] Thanks to the small energy difference (DE ST ) between the lowest singlet (S 1 )and triplet (T 1 )states,they can realize atheoretical 100 %internal quantum efficiency (IQE) through at hermally assisted reverse intersystem crossing from T 1 to S 1 .I n2 012, Adachi and co-workers prepared ag roup of carbazolyl dicyanobenzene derivatives, [9] and demonstrated that their delayed fluorescence efficiencies were comparable to those of phosphors.S ince then, much effort has been focused on the design of numerous TADF small molecules with efficient deep-blue to near-infrared emissions, [10][11][12][13] whose device fabrication relies on an expensive vacuum deposition technique.B yc ontrast, the development of TADF polymers,c apable of low-cost wet methods including spin-coating and inkjet printing,i ss till lagging behind in terms of amount and efficiency. [14,15] Generally,s everal principles could be adopted for the design of TADF polymers (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Bridging Small Molecules to Conjugated Polymers: Efficient Thermally Activated Delayed Fluorescence with a Methyl‐Substituted Phenylene Linker

Rao

Liu

et al. 2019

Angew Chem Int Ed

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Based on a “TADF + Linker” strategy (TADF=thermally activated delayed fluorescence), demonstrated here is the successful construction of conjugated polymers that allow highly efficient delayed fluorescence. Small molecular TADF blocks are linked together using a methyl‐substituted phenylene linker to form polymers. With the growing number of methyl groups on the phenylene, the energy level of the local excited triplet state (3LEb) from the delocalized polymer backbone gradually increases, and finally surpasses the charge‐transfer triplet state (3CT). As a result, the diminished delayed fluorescence can be recovered for the tetramethyl phenylene containing polymer, revealing a record‐high external quantum efficiency (EQE) of 23.5 % (68.8 cd A−1, 60.0 lm W−1) and Commission Internationale de l′Eclairage (CIE) coordinates of (0.25, 0.52). Combined with an orange‐red TADF emitter, a bright white electroluminescence is also obtained with a peak EQE of 20.9 % (61.1 cd A−1, 56.4 lm W−1) and CIE coordinates of (0.36, 0.51).

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Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off

Cited by 720 publications

References 39 publications

Insights into the Optical Properties of Triarylboranes with Strongly Electron‐Accepting Bis(fluoromesityl)boryl Groups: when Theory Meets Experiment

Insights into the Optical Properties of Triarylboranes with Strongly Electron‐Accepting Bis(fluoromesityl)boryl Groups: when Theory Meets Experiment

Electron‐Rich Twistacene‐Modified Arylboron Donor–Acceptor Systems: Synthesis, Photophysics, and Electroluminescence with Hot Exciton Response

Bridging Small Molecules to Conjugated Polymers: Efficient Thermally Activated Delayed Fluorescence with a Methyl‐Substituted Phenylene Linker

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