Purely organic pyridium-based materials with thermally activated delayed fluorescence for orange-red light-emitting electrochemical cells

Shen, Hsiang‐Ling; Hsiao, Pei-Wan; Yi, Rong-Huei; Su, Yi-Hua; Yin, Chen; Lu, Chin‐Wei; Su, Hai‐Ching

doi:10.1016/j.dyepig.2022.110346

Cited by 18 publications

(10 citation statements)

References 68 publications

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“…Recently, we proposed red LECs employing ionic TADF small molecules. [164] However, the EL emission peak wavelengths were ca. 600 nm and were still far from deep-red or NIR region.…”

Section: Discussionmentioning

confidence: 99%

Long‐Wavelength Light‐Emitting Electrochemical Cells: Materials and Device Engineering

Lin

2022

Chemistry A European J

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Long‐wavelength light‐emitting electrochemical cells (LECs) are potential deep‐red and near infrared light sources with solution‐processable simple device architecture, low‐voltage operation, and compatibility with inert metal electrodes. Many scientific efforts have been made to material design and device engineering of the long‐wavelength LECs over the past two decades. The materials designed the for long‐wavelength LECs cover ionic transition metal complexes, small molecules, conjugated polymers, and perovskites. On the other hand, device engineering techniques, including spectral modification by adjusting microcavity effect, light outcoupling enhancement, energy down‐conversion from color conversion layers, and adjusting intermolecular interactions, are also helpful in improving the device performance of long‐wavelength LECs. In this review, recent advances in the long‐wavelength LECs are reviewed from the viewpoints of materials and device engineering. Finally, discussions on conclusion and outlook indicate possible directions for future developments of the long‐wavelength LECs. This review would like to pave the way for the researchers to design materials and device engineering techniques for the long‐wavelength LECs in the applications of displays, bio‐imaging, telecommunication, and night‐vision displays.

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“…Recently, we proposed red LECs employing ionic TADF small molecules. [164] However, the EL emission peak wavelengths were ca. 600 nm and were still far from deep-red or NIR region.…”

Section: Discussionmentioning

confidence: 99%

Long‐Wavelength Light‐Emitting Electrochemical Cells: Materials and Device Engineering

Lin

2022

Chemistry A European J

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“…Fundamental research has resulted in an improved understanding of the complex LEC working mechanism, [4][5][6] which in turn has paved the way for devices with increased efficiency, a broader color gamut, and prolonged operational lifetime. [6][7][8] The most common emitting materials in LECs are conjugated polymers, [6,[9][10][11] small molecules, [12][13][14][15][16] quantum dots, [17][18][19][20] and ionic transition metal complexes (iTMCs). [10,[21][22][23][24] The latter are particularly efficient as spin-orbit coupling (SOC) enables for harvesting of all electrically generated excitons (i.e., both triplets and singlets) for light emission.…”

Section: Introductionmentioning

confidence: 99%

Broadband White‐Light‐Emitting Electrochemical Cells

Adranno

Tang

Paterlini

et al. 2023

Advanced Photonics Research

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Emerging organic light‐emitting devices, such as light‐emitting electrochemical cells (LECs), offer a multitude of advantages but currently suffer from that most efficient phosphorescent emitters are based on expensive and rare metals. Herein, it is demonstrated that a rare metal‐free salt, bis(benzyltriphenylphosphonium)tetrabromidomanganate(II) ([Ph3PBn]2[MnBr4]), can function as the phosphorescent emitter in an LEC, and that a careful device design results in the fact that such a rare metal‐free phosphorescent LEC delivers broadband white emission with a high color rendering index (CRI) of 89. It is further shown that broadband emission is effectuated by an electric‐field‐driven structural transformation of the original green‐light emitter structure into a red‐emitting structure.

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“…Recently, a novel type of fluorescent materials with thermally activated delayed fluorescence (TADF) [32] has been demonstrated to be capable of recycling the triplet excitons on them via efficient reverse intersystem crossing (RISC), leading to phosphorescent EL efficiencies. In view of such a high potential, neat-film [33][34][35][36] and host-guest [37][38][39][40][41][42][43] TADF LECs have been proposed. The host-guest TADF LECs generally showed higher device efficiencies than the neat-film TADF LECs due to reduced self-quenching and a lower possibility of triplet-triplet annihilation on the TADF guest molecules, which is a strong competing process against RISC.…”

Section: Introductionmentioning

confidence: 99%

White Light‐Emitting Electrochemical Cells Employing Phosphor‐Sensitized Thermally Activated Delayed Fluorescence to Approach All‐Phosphorescent Device Efficiencies

Chen

Huang

Luo

et al. 2023

Chemistry A European J

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Solid-state light-emitting electrochemical cells (LECs) show promising advantages of simple device architecture, low operation voltage, and insensitivity to the electrode work functions such that they have high potential in low-cost display and lighting applications. In this work, novel white LECs based on phosphor-sensitized thermally activated delayed fluorescence (TADF) are proposed. The emissive layer of these white LECs is composed of a blue-green phosphorescent host doped with a deep-red TADF guest. Efficient singlet-to-triplet intersystem crossing (ISC) on the phosphorescent host and the subsequent Förster energy transfer from the host triplet excitons to guest singlet excitons can make use of both singlet and triplet excitons on the host. With the good spectral overlap between the host emission and the guest absorption, 0.075 wt.% guest doping is sufficient to cause substantial energy transfer efficiency (ca. 40 %). In addition, such a low guest concentration also reduces the self-quenching effect and a high photoluminescence quantum yield of up to 84 % ensures high device efficiency. The phosphor-sensitized TADF white LECs indeed show a high external quantum efficiency of 9.6 %, which is comparable with all-phosphorescent white LECs. By employing diffusive substrates to extract the light trapped in the substrate, the device efficiency can be further improved by ca. 50 %. In the meantime, the intrinsic EL spectrum and device lifetime of the white LECs recover since the microcavity effect is destroyed. This work successfully demonstrates that the phosphor-sensitized TADF white LECs are potential candidates for efficient white light-emitting devices.

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Purely organic pyridium-based materials with thermally activated delayed fluorescence for orange-red light-emitting electrochemical cells

Cited by 18 publications

References 68 publications

Long‐Wavelength Light‐Emitting Electrochemical Cells: Materials and Device Engineering

Long‐Wavelength Light‐Emitting Electrochemical Cells: Materials and Device Engineering

Broadband White‐Light‐Emitting Electrochemical Cells

White Light‐Emitting Electrochemical Cells Employing Phosphor‐Sensitized Thermally Activated Delayed Fluorescence to Approach All‐Phosphorescent Device Efficiencies

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