Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

Karaman, Merve; Gupta, Abhishek Kumar; Suresh, Subeesh Madayanad; Matulaitis, Tomas; Mardegan, Lorenzo; Tordera, Daniel; Bolink, Henk J.; Wu, Sen; Warriner, Stuart; Samuel, Ifor D. W.; Zysman‐Colman, Eli

doi:10.3762/bjoc.18.136

Cited by 13 publications

(11 citation statements)

References 45 publications

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“…[ 32 ] The color purity of these results was better than that of recently reported LECs with MR‐TADF emitters. [ 33,34 ] Therefore, we concluded that the realization of ultrapure blue EL emissions based on solution‐processable LECs could contribute greatly to the creation of a sustainable society in the future.…”

Section: Resultsmentioning

confidence: 99%

Solution‐Processable Ultrapure‐Blue Light‐Emitting Electrochemical Cells

Tanaka,

Ito,

Liu

et al. 2023

Advanced Optical Materials

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Light‐emitting electrochemical cells (LECs) have attracted considerable attention owing to their unique luminescence mechanisms and device structures, making them suitable for solution processing. However, these cells encounter problems related to color purity, which plays an important role in efficient and high‐resolution displays. Here, two types of solution‐processed LECs are reported that exhibit ultrapure blue emissions at 467 and 452 nm with narrow emission full‐widths at half‐maximum (FWHM) values of 21 and 30 nm, corresponding to the Commission Internationale de l'éclairage (CIE) coordinates of (0.12, and 0.15) and (0.16, 0. and 10), respectively. These values are obtained using the multi‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) materials, namely, ν‐DABNA and DABNA‐4TBC. The suppression of structural relaxation and vibronic coupling in these MR‐TADF materials results in high‐color‐purity emissions with a small FWHM. Host‐guest‐type LECs employing these molecules as guest emitters in a spin‐coated single active layer exhibit both ultrapure blue electroluminescence (EL) and solution processability, strongly supporting their use in building a sustainable society in the future.

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Section: Resultsmentioning

confidence: 99%

Solution‐Processable Ultrapure‐Blue Light‐Emitting Electrochemical Cells

Tanaka,

Ito,

Liu

et al. 2023

Advanced Optical Materials

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“…After confirming a TADF emission mechanism, we turned our attention on the influence of ionic additives employed in the active layer of the final device, vide infra , as it has been demonstrated that the presence of ionic additives can alter similarly the spin-vibronic coupling. [21,31,57] Thus, morphology and photophysical response of films embedding dendrimers and ion polyelectrolyte was also studied. Since the appropriate selection of the electrolyte is crucial to meet high performing LECs, we explored a wide variety of traditional ion-based electrolytes in LECs, namely PEO-based electrolytes, ionic liquids, inorganic salts, etc.…”

Section: Photophysical Properties In Thin Filmsmentioning

confidence: 99%

Dendri‐LEC Family: Establishing the Bright Future for Dendrimer Emitters in Traditional and Graphene‐Based Light‐Emitting Electrochemical Cells

Cavinato,

Yamaoka,

Lipinski

et al. 2023

Adv Funct Materials

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A rational implementation and optimization of thermally activated delayed fluorescent (TADF) dendrimer emitters in light‐emitting electrochemical cells (LECs) sets in the Dendri‐LEC family. They feature outstanding stabilities (90/1050 h for green/yellow devices) that are comparable to the best green/yellow Ir(III)‐complexes (450/500 h) and conjugated polymers (33/5500 h), while offering benefits of low‐cost synthesis and easy upscaling. In particular, a fundamental molecular design that capitalizes on exchanging peripheral substituents (tert‐butyl vs methoxy) to tune photophysical, electrochemical, morphological, and ion conductivity features in thin films is rationalized by temperature‐dependent steady‐state and time‐resolved emission spectroscopy, cyclic voltammetry, atomic force microscopy, and electrochemical impedance spectroscopy techniques. Herein, a TADF mechanism associated to a reduced photoluminescence quantum yield, but an enhanced electrochemical stability and ion conductivity enables to clarify the reduced device efficiency and brightness (4.0 lm W−1@110 cd m−2 vs 3.2 lm W−1@55 cd m−2) and increased stability (90 vs 1050 h) upon using methoxy groups. What is more, this substitution enables an excellent compatibility with biogenic electrolytes keeping device performances (1.9 lm W−1@35 cd m−2 and 1300 h), while graphene‐devices achieve on par figures to traditional indium–tin oxide‐devices. Overall, this work establishes the bright future of dendrimer emitters toward highly stable and truly sustainable lighting sources.

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“…40 Karaman et al recently reported on the synthesis of two cationic MR-TADF compounds, which comprised a DiKTa 41 core endowed with a chemically grafted imidazolium cation that is chargecompensated by a mobile PF 6 − anion. 42 They introduced a neat thin lm of one, or a blend, of these two ionic compounds as the active material in an LEC device, which delivered electroluminescence. The drawbacks were that the peak luminance and the EQE were modest at 15 cd/m 2 and < 0.01%, respectively, and that the emission spectrum was broad with a FWHM of > 100 nm.…”

Section: Introductionmentioning

confidence: 99%

“…The drawbacks were that the peak luminance and the EQE were modest at 15 cd/m 2 and < 0.01%, respectively, and that the emission spectrum was broad with a FWHM of > 100 nm. 42 Here, we report on the development of the rst MR-TADF LEC that delivers bright and narrowband emission at 500 cd/m 2 and a FWHM of 31 nm, respectively, at a high EQE of 3.8%. The peak wavelength of the blue-emitting MR-TADF LEC is 489 nm and the CIE coordinates are (0.11, 0.35).…”

Section: Introductionmentioning

confidence: 99%

Introducing MR-TADF Emitters into Light-Emitting Electrochemical Cells for Narrowband and Efficient Emission

Edman

Tang

Santos

et al. 2023

Preprint

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Organic semiconductors that emit by the process of multi-resonance thermally activated delayed fluorescence (MR-TADF) can deliver narrowband and efficient electroluminescence while being processable from solvents and metal free. This renders them attractive for use as the emitter in sustainable light-emitting electrochemical cells (LECs), but so far reports on narrowband and efficient MR-TADF emission from LEC devices are absent. Here, we address this issue through careful and systematic material selection and device development. Specifically, we show that the detrimental aggregation tendency of an archetypal rigid and planar carbazole-based MR-TADF emitter can be inhibited by its dispersion into a compatible carbazole-based blend host and an ionic-liquid electrolyte; and we further demonstrate that the tuning of this active material results in the desired achievement of balanced p- and n-type electrochemical doping, high solid-state photoluminescence quantum yield of 91%, singlet and triplet trapping on the MR-TADF guest emitter, and similarly sized electron and hole transport traps. The introduction of this designed metal-free active material into an MR-TADF LEC results in the attainment of bright blue electroluminescence of 500 cd/m2, which is delivered at a high external quantum efficiency of 3.8% and a narrow full-width-at-half-maximum of 31 nm.

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Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

Cited by 13 publications

References 45 publications

Solution‐Processable Ultrapure‐Blue Light‐Emitting Electrochemical Cells

Solution‐Processable Ultrapure‐Blue Light‐Emitting Electrochemical Cells

Dendri‐LEC Family: Establishing the Bright Future for Dendrimer Emitters in Traditional and Graphene‐Based Light‐Emitting Electrochemical Cells

Introducing MR-TADF Emitters into Light-Emitting Electrochemical Cells for Narrowband and Efficient Emission

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