Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units

Hall, David; Stavrou, Kleitos; Du̅da, Eimantas; Danos, Andrew; Bagnich, S. A.; Warriner, Stuart; Slawin, Alexandra M. Z.; Beljonne, David; Köhler, Anna; Monkman, Andrew P.; Olivier, Yoann; Zysman‐Colman, Eli

doi:10.1039/d1mh01383a

Cited by 81 publications

(109 citation statements)

References 72 publications

(128 reference statements)

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“…30 The longest delayed component is attributed to pure monomer emission with mono-excitonic origin, in contrast with α-3BNOH where it was found to have bi-excitonic TTA contribution (Figure S13). As in other recent studies of MR-TADF materials, 15,18 we find that changing the host matrix has only a modest influence on kRISC (Figure S12b). Finally, the photoluminescence quantum yield (PLQY) of α-3BNMes in 1% mCP doped film was determined to be 63%, thus nearly double that of α-3BNOH (35% in 1 wt% mCP), and is sufficiently high to support OLED applications.…”

Section: Optical Propertiessupporting

confidence: 89%

“…14 MR-TADF compounds show TADF due to the alternating pattern of electron density between the ground and excited states that leads to small DEST, combined with upper-triplet crossings from thermally-populated Tn states back to the emissive S1 state. [15][16][17][18] The excited states thus possess a distinct short range charge transfer (SRCT) character, 13,19,20 and MR-TADF compounds are endowed with high singlet radiative decay (kr) rates of around 10 7 s -1 . 5,19 Despite these advantages, the RISC rates reported for MR-TADF materials typically lag ~100 times slower than those of leading D-A or D-A-D TADF materials.…”

Section: Introductionmentioning

confidence: 99%

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Emission and Absorption Tuning in MR-TADF B,N-Doped Hep-tacenes: Towards Ideal-Blue Hyperfluorescent OLEDs

Stavrou

Suresh

Hall

et al. 2022

Preprint

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Developing high-efficiency purely organic blue organic light-emitting diodes (OLEDs) that meet the stringent industry standards is a major current research challenge. Hyperfluorescent device approaches achieve in large measure the desired high performance by combining the advantages of a high-efficiency thermally activated delayed fluorescence (TADF) assistant dopant with a narrowband deep-blue multi-resonant TADF (MR-TADF) terminal emitter. However, this ap-proach requires suitable spectral overlap to support Förster resonance energy transfer (FRET) between the two. Here we demonstrate colour tuning of a recently reported MR-TADF B,N-heptacene core through control of the boron substituents. While there is little impact on the intrinsic TADF properties - as both singlet and triplet energies decrease in tandem - this approach improves the emission colour coordinate as well as the spectral overlap for blue hyperfluorescence OLEDs (HF OLEDs). Crucially, the red-shifted and more intense absorption allows us to pair this MR-TADF emitter with a high-performance TADF assistant dopant and achieve maximum external quantum efficiency (EQEmax) of 15% at colour coordinates of (0.15, 0.10). The efficiency values recorded for our device at a practical luminance of 100 cd m-2 are among the highest reported for HF TADF OLEDs with CIEy ≤ 0.1.

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Section: Optical Propertiessupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Emission and Absorption Tuning in MR-TADF B,N-Doped Hep-tacenes: Towards Ideal-Blue Hyperfluorescent OLEDs

Stavrou

Suresh

Hall

et al. 2022

Preprint

Self Cite

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“…[15] MR-TADF compounds show TADF due to the alternating pattern of electron density between the ground and excited states that leads to small ΔE ST , combined with upper-triplet crossings from thermally populated T n states back to the emissive S 1 state. [16][17][18][19] The excited states thus possess a distinct short-range charge transfer (SRCT) character, [14,20,21] and MR-TADF compounds are endowed with high singlet radiative decay (k r ) rates of around 10 7 s -1 . [5,20] Despite these advantages, the RISC rates reported for MR-TADF materials typically lag ~100 times slower than those of leading D-A or D-A-D TADF materials.…”

Section: Introductionmentioning

confidence: 99%

Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs

Stavrou

Suresh

Hall

et al. 2022

Advanced Optical Materials

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Developing high‐efficiency purely organic blue organic light‐emitting diodes (OLEDs) that meet the stringent industry standards is a major current research challenge. Hyperfluorescent device approaches achieve in large measure the desired high performance by combining the advantages of a high‐efficiency thermally activated delayed fluorescence (TADF) assistant dopant with a narrowband deep‐blue multi‐resonant TADF (MR‐TADF) terminal emitter. However, this approach requires suitable spectral overlap to support Förster resonance energy transfer (FRET) between the two. Here, a color tuning of a recently reported MR‐TADF B,N‐heptacene core through control of the boron substituents is demonstrated. While there is little impact on the intrinsic TADF properties—as both singlet and triplet energies decrease in tandem—this approach improves the emission color coordinate as well as the spectral overlap for blue hyperfluorescence OLEDs (HF OLEDs). Crucially, the red‐shifted and more intense absorption allows the new MR‐TADF emitter to pair with a high‐performance TADF assistant dopant and achieve maximum external quantum efficiency (EQEmax) of 15% at color coordinates of (0.15 and 0.10). The efficiency values recorded for the device at a practical luminance of 100 cd m–2 are among the highest reported for HF TADF OLEDs with CIEy ≤ 0.1.

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“…showed that the MR‐TADF emitters can exhibit both small Δ E ST and high

f_{S_1 S_0}

, [ 42 ] which opens the possibility to increase the device performance. However, the MR‐TADF emitters are rare, and most of them are nanographenes doped with both donor and acceptor atoms, such as O, B, and N. [ 41 ] Recently proposed DilCzMes4 is the first acceptor‐free MR‐TADF that contains only nitrogen as donor, [ 43 ] showing an unexplored frontier in MR‐TADF design.…”

Section: Design Of Thermally‐activated Delayed Fluorescence Emittersmentioning

confidence: 99%

Virtual Screening for Organic Solar Cells and Light Emitting Diodes

et al. 2022

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We dedicate this contribution to Klaus Müllen on the occasion of his 75th birthday. He advanced the synthesis and application of organic electronic compounds in an internationally leading position for many years and always challenged theory to provide a better understanding.The field of organic semiconductors is multifaceted and the potentially suitable molecular compounds are very diverse. Representative examples include discotic liquid crystals, dye-sensitized solar cells, conjugated polymers, and graphene-based low-dimensional materials. This huge variety not only represents enormous challenges for synthesis but also for theory, which aims at a comprehensive understanding and structuring of the plethora of possible compounds. Eventually computational methods should point to new, better materials, which have not yet been synthesized. In this perspective, it is shown that the answer to this question rests upon the delicate balance between computational efficiency and accuracy of the methods used in the virtual screening. To illustrate the fundamentals of virtual screening, chemical design of non-fullerene acceptors, thermally activated delayed fluorescence emitters, and nanographenes are discussed.

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Diindolocarbazole – achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units

Abstract: We present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms.

Cited by 81 publications

References 72 publications

Emission and Absorption Tuning in MR-TADF B,N-Doped Hep-tacenes: Towards Ideal-Blue Hyperfluorescent OLEDs

Emission and Absorption Tuning in MR-TADF B,N-Doped Hep-tacenes: Towards Ideal-Blue Hyperfluorescent OLEDs

Emission and Absorption Tuning in TADF B,N‐Doped Heptacenes: Toward Ideal‐Blue Hyperfluorescent OLEDs

Virtual Screening for Organic Solar Cells and Light Emitting Diodes

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