Rotation-restricted thermally activated delayed fluorescence compounds for efficient solution-processed OLEDs with EQEs of up to 24.3% and small roll-off

Li, Kuofei; Zhu, Yunhui; Yao, Bing; Chen, Yuannan; Deng, Hao; Zhang, Qisheng; Zhan, Hongmei; Xie, Zhiyuan; Cheng, Yanxiang

doi:10.1039/d0cc01738h

Cited by 62 publications

(47 citation statements)

References 37 publications

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“…Second, the electron cloud overlap between donor and acceptor can be reduced, beneficial for reducing DE ST and achieving TADF effect. [4,[50][51][52][53][54][55][56][57][58] Using this strategy,T ADF polymers with emission covering the whole visible spectra from deep blue to red region have been developed. [48] However,t hese TSCT polymers suffer from unpredictable spatial alignment of donor and acceptor because both of them are attached in different repeating units and can motion freely relative to each other,limiting the understanding of throughspace CT processes.T herefore,itisdesired to develop TSCT polymers where donors and acceptors can be fixed and controlled for modulating the through-space interactions.…”

Section: Introductionmentioning

confidence: 99%

Through‐Space Charge‐Transfer Polynorbornenes with Fixed and Controllable Spatial Alignment of Donor and Acceptor for High‐Efficiency Blue Thermally Activated Delayed Fluorescence

et al. 2020

Angew Chem Int Ed

140

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Through-space charge transfer polynorbornenes with fixeda nd controllable spatial alignment of donor and acceptor in edge-to-face/face-to-face stacking patterns are developed for achieving high-efficiency blue thermally activated delayed fluorescence (TADF). The alignment is realized by using the cis,e xo-configuration of norbornene to confine donor and acceptor in close proximity, and utilizing orthogonal and dendritic structures of donors to provide either perpendicular or parallel stackingm otif relative to acceptors. Compared to edge-to-face counterparts,polynorbornenes with face-to-face aligned donor and acceptor exhibit muchl arger oscillator strength and higher photoluminescence quantum yield. The resulting polymers exhibit deep blue (422 nm) to sky blue (482 nm) emission and TADF effect with reverse intersystem crossing rates of 0.4-5.9 10 6 s À1 ,giving the maximum external quantum efficiency of 18.8 %f or non-doped blue organic light-emitting diodes by solution process.

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Section: Introductionmentioning

confidence: 99%

Through‐Space Charge‐Transfer Polynorbornenes with Fixed and Controllable Spatial Alignment of Donor and Acceptor for High‐Efficiency Blue Thermally Activated Delayed Fluorescence

et al. 2020

Angew Chem Int Ed

140

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“…One is through‐bond charge transfer (TBCT) mediated by conjugated bonds, [ 1 ] which features strong electron coupling between donor and acceptor through covalent bonds, while the other is through‐space charge transfer (TSCT), which occurs through spatial electron interactions and has relatively weaker electron coupling between donor and acceptor. [ 11–25 ]…”

Section: Introductionmentioning

confidence: 99%

Through‐space charge transfer polymers for solution‐processed organic light‐emitting diodes

2020

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Through‐space charge transfer (TSCT) polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect, different from conventional luminescent polymers with conjugated donor‐acceptor structure and through‐bond charge transfer emission. Their emission comes from the intramolecular charge transfer by through‐space pathway because the donor and acceptor segments are spatially proximate to each other in each repeating unit but are physically separated by nonconjugated polymer backbone. In this review, recent advances in TSCT polymers with linear, bottlebrush, and dendritic architectures are presented, with the focus on their molecular design, photophysical behavior, and device performance. We hope that this review shall provide a useful insight of new luminescent polymers with TSCT effect for use in solution‐processed organic light‐emitting diodes.

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“…A common approach to achieve RISC is to carefully combine electron donor and acceptor units within a chromophore, so as to allow for intramolecular charge transfer (ICT). Numerous design strategies have been reported, and in a number of cases efficient TADF has been shown to result from combining multiple separate photophysical processes, including charge transfer (CT) and locally excited states [2c, 14] . In most TADF chromophores (i) the highest occupied molecular orbital (HOMO) is well separated from lowest unoccupied molecular orbital (LUMO), and (ii) the energy gap between the T and S excited states (Δ E ST ) amounts to less that ≈0.2 eV [3] .…”

Section: Figurementioning

confidence: 99%

Tuning Optical Properties by Controlled Aggregation: Electroluminescence Assisted by Thermally‐Activated Delayed Fluorescence from Thin Films of Crystalline Chromophores

Haldar

Jakoby

Kozłowska

et al. 2020

Chemistry A European J

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Several photophysical properties of chromophores depend crucially on intermolecular interactions. Thermally‐activated delayed fluorescence (TADF) is often influenced by close packing of the chromophore assembly. In this context, the metal‐organic framework (MOF) approach has several advantages: it can be used to steer aggregation such that the orientation within aggregated structures can be predicted using rational approaches. We demonstrate this design concept for a DPA‐TPE (diphenylamine‐tetraphenylethylene) chromophore, which is non‐emissive in its solvated state due to vibrational quenching. Turning this DPA‐TPE into a ditopic linker makes it possible to grow oriented MOF thin films exhibiting pronounced green electroluminescence with low onset voltages. Measurements at different temperatures clearly demonstrate the presence of TADF. Finally, this work reports that the layer‐by‐layer process used for MOF thin film deposition allows the integration of the TADF‐DPA‐TPE in a functioning LED device.

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Rotation-restricted thermally activated delayed fluorescence compounds for efficient solution-processed OLEDs with EQEs of up to 24.3% and small roll-off

Abstract: A sandwich-like chromophore, composed of two donors and an inserted acceptor, is hitched onto a single carbazole to yield an efficient TADF emitter with excellent electroluminescent performance.

Cited by 62 publications

References 37 publications

Through‐Space Charge‐Transfer Polynorbornenes with Fixed and Controllable Spatial Alignment of Donor and Acceptor for High‐Efficiency Blue Thermally Activated Delayed Fluorescence

Through‐Space Charge‐Transfer Polynorbornenes with Fixed and Controllable Spatial Alignment of Donor and Acceptor for High‐Efficiency Blue Thermally Activated Delayed Fluorescence

Through‐space charge transfer polymers for solution‐processed organic light‐emitting diodes

Tuning Optical Properties by Controlled Aggregation: Electroluminescence Assisted by Thermally‐Activated Delayed Fluorescence from Thin Films of Crystalline Chromophores

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