Interactions of Solid Supports and Fluorescent Substances in Thermally Activated Delayed Fluorescence

Onoue, Yoshiaki; Hiraki, Kei; Nishikawa, Yasuharu

doi:10.2116/analsci.3.509

Cited by 7 publications

(4 citation statements)

References 3 publications

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“…In this regard, copper(I)-based iTMCs (Cu-iTMCs) are attracting more and more attention, since they are considered as a serious alternative to the well-known iridium(III)-based iTMCs (Ir-iTMCs). , The interest in Cu-iTMCs is justified by (i) the absence of metal-centered (MC) excited states that are typical degradative pathways for iridium(III) complexes, ,− (ii) the emission mechanism involving a thermally activated delayed fluorescence (TADF) that results in high photoluminescence quantum yields (Φ), − (iii) the large number of emitting families, ,, and (iv) the low production costs related to the use of a relatively abundant and cheaper metal with respect to iridium.…”

Section: Introductionmentioning

confidence: 99%

Novel Ligand and Device Designs for Stable Light-Emitting Electrochemical Cells Based on Heteroleptic Copper(I) Complexes

et al. 2018

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This work reports on the positive impact of (i) attaching methoxy groups at the ortho position of the bipyridine ligand (6,6'-dimethoxy-2,2'-bipyridine) in heteroleptic copper(I) complexes belonging to the [Cu(bpy)(POP)] family, and (ii) a new device design comprising a multilayered architecture to decouple hole/electron injection and transport processes on the performance of light-emitting electrochemical cells (LECs). In short, the substituted complex showed enhanced thermal- and photostability, photoluminescence, and ionic conductivity features in thin films compared to those of the archetypal complex without substitution. These beneficial features led to LECs outperforming reference devices in terms of luminance, stability, and efficacy. Furthermore, a new device design resulted in a 10-fold enhancement of the stability without negatively affecting the other figures of merit. Here, hole/electron injection and transport processes are performed at two different layers, while electron injection and electron-hole recombination occur at the copper(I) complex layer. As such, this work provides further insights into a smart design of N^N ligands for copper(I) complexes, opening the path to a simple device architecture toward an enhanced electroluminescence response.

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Section: Introductionmentioning

confidence: 99%

Novel Ligand and Device Designs for Stable Light-Emitting Electrochemical Cells Based on Heteroleptic Copper(I) Complexes

et al. 2018

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“…2 Recently, an alternative approach was demonstrated whereby emitters fluoresce from triplet states via thermal up-conversion to the singlet state. 3 The system, named thermally activated delayed fluorescence (TADF), 4 has since been vigorously investigated. 5 Although TADF materials containing heavy-metals (e.g.…”

Section: Introductionmentioning

confidence: 99%

Molecular Design Realizing Very Fast Reverse Intersystem Crossing in Purely Organic Emitter

wada¹,

Nakagawa²,

Matsumoto³

et al. 2019

Preprint

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Reverse intersystem crossing (RISC), originally considered forbidden in purely organic materials, has been recently enabled by minimizing the energy gap between the lowest singlet excited state (S1) and lowest triplet state (T1) in thermally activated delayed fluorescence (TADF) systems. However, direct spin-inversion between S1 and T1 is still inefficient when both states are of the same charge transfer (CT) nature (i.e. 1CT and 3CT, respectively). Intervention of locally excited triplet states (3LE) between 1CT and 3CT is expected to trigger fast spin-flip. Here, we report on the systematic-design of the ideal TADF molecules with near-degenerate 1CT, 3CT and 3LE states by controlling the through-space distance between the donor and acceptor segments in a molecule with tilted intersegment angles. The new system realizes very fast RISC with a rate constant (kRISC) of 1.2×107 s−1. The large kRISC of the emitter resulted in great device performance in the applications to blue TADF assisted fluorescence organic light-emitting diodes (OLEDs) as well as TADF-emitter OLEDs.

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“…Materials that have E-type delayed fluorescence, namely thermally activated delayed fluorescence (TADF), [1] have recently drawn great interest in the field of organic light-emitting diodes. This is because utilization of triplet excitons to generate light is crucial for achieving high performance devices with lowenergy consumption.…”

mentioning

confidence: 99%

“…Recently, in addition to formation of degenerate CT-type S 1 and T 1 , inclusion of different excited states, such as locally excited triplet states ( 3 LE), has drawn attention for increasing the rate constant of RISC (k RISC ). Materials that have a small energy difference between 1 CT and 3 LE have good TADF performance. [3g,n,o,5] However, there remain questions over the nature of the additional states and whether these are limited to 3 LE.…”

mentioning

confidence: 99%

Acceleration of Reverse Intersystem Crossing using Different Types of Charge Transfer States

Wada

Nakagawa

Kaji

2021

Chemistry An Asian Journal

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There is a need to boost the rate constant of reverse intersystem crossing (k RISC ) in thermally activated delayed fluorescence (TADF) materials for applications to organic light-emitting diodes. Recently, energy level matching of the locally excited state (LE) and charge transfer state (CT) has been reported to enhance k RISC . In this study, we conceptually demonstrate that k RISC can be improved even between CT states without LE states, through the use of different types of CT states. On the basis of this concept, we design a new compound, named DMAC-bPmT, where two phenyl groups of a well-known TADF material DMAC-TRZ are substituted by pyrimidine groups. Theoretical calculations indicated that the energy levels of the different CT states of DMAC-bPmT are very close and enhanced spin orbit coupling may be expected between them. As predicted, DMAC-bPmT experimentally exhibited a k RISC three times as high as that of DMAC-TRZ.

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Interactions of Solid Supports and Fluorescent Substances in Thermally Activated Delayed Fluorescence

Cited by 7 publications

References 3 publications

Novel Ligand and Device Designs for Stable Light-Emitting Electrochemical Cells Based on Heteroleptic Copper(I) Complexes

Novel Ligand and Device Designs for Stable Light-Emitting Electrochemical Cells Based on Heteroleptic Copper(I) Complexes

Molecular Design Realizing Very Fast Reverse Intersystem Crossing in Purely Organic Emitter

Acceleration of Reverse Intersystem Crossing using Different Types of Charge Transfer States

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