Referential tuning strategy for high-lying triplet energy level setting in OLED emitter with hot-exciton characteristics

Ke, Qinqin; Song, Yuxi; Li, Ganggang; Li, Baoxi; Chen, Yiwen; Wan, Qing; Ma, Dongge; Wang, Zhiming; Tang, Ben Zhong

doi:10.1039/d2tc01036d

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…This hypothesis was proven by comparing two D-A-D molecules that combined a naphtho[2,3-d][1,2,3]triazole (NMZ) core and either naphthalene (Np) or anthracene (An) substituents. The T 1 energy of Np was higher than the T 1 energy of An, and, subsequently, Np-NMZ-Np had a larger T 2 -T 1 energy gap than An-NMZ-An [80]. In addition, for a D-A type molecule, the electronic coupling between LE T 1 and CT T 2 states correlates with the electron exchange between the donor and the acceptor fragments.…”

Section: Hot Exciton Materials Designmentioning

confidence: 91%

“…Although the hot exciton process does not obey Kasha's rule, numerous hot exciton materials have been reported [20,[68][69][70][71][72][73][74][75][76]. A comprehensive review on the reported cases of hot exciton materials can be found elsewhere [20], and some representative molecules are shown in Figure 5 [51, [77][78][79][80][81][82][83] with their photophysical properties summarized in Table 1. Ideally, hot exciton materials have several advantages.…”

Section: Hot Exciton Processmentioning

confidence: 99%

“…As most hRISC processes initiate from T 2 states, increasing the T 2 -T 1 energy gap will be a good strategy. When there is a core fragment with a given T 1 energy, if we introduce a substituent with a much higher T 1 energy of its own, the T 2 energy of the whole molecule will be close to the T 1 energy of the added substituent [80,115] as long as the T 2 energy of the original core part is even higher. This hypothesis was proven by comparing two D-A-D molecules that combined a naphtho[2,3-d][1,2,3]triazole (NMZ) core and either naphthalene (Np) or anthracene (An) substituents.…”

Section: Hot Exciton Materials Designmentioning

confidence: 99%

See 2 more Smart Citations

Overcoming the Limitation of Spin Statistics in Organic Light Emitting Diodes (OLEDs): Hot Exciton Mechanism and Its Characterization

Park

Kim

Rhee

2023

IJMS

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Triplet harvesting processes are essential for enhancing efficiencies of fluorescent organic light-emitting diodes. Besides more conventional thermally activated delayed fluorescence and triplet-triplet annihilation, the hot exciton mechanism has been recently noticed because it helps reduce the efficiency roll-off and improve device stability. Hot exciton materials enable the conversion of triplet excitons to singlet ones via reverse inter-system crossing from high-lying triplet states and thereby the depopulation of long-lived triplet excitons that are prone to chemical and/or efficiency degradation. Although their anti-Kasha characteristics have not been clearly explained, numerous molecules with behaviors assigned to the hot exciton mechanism have been reported. Indeed, the related developments appear to have just passed the stage of infancy now, and there will likely be more roles that computational elucidations can play. With this perspective in mind, we review some selected experimental studies on the mechanism and the related designs and then on computational studies. On the computational side, we examine what has been found and what is still missing with regard to properly understanding this interesting mechanism. We further discuss potential future points of computational interests toward aiming for eventually presenting in silico design guides.

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Section: Hot Exciton Materials Designmentioning

confidence: 91%

Section: Hot Exciton Processmentioning

confidence: 99%

Section: Hot Exciton Materials Designmentioning

confidence: 99%

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Overcoming the Limitation of Spin Statistics in Organic Light Emitting Diodes (OLEDs): Hot Exciton Mechanism and Its Characterization

Park

Kim

Rhee

2023

IJMS

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“…[19][20][21][22] The efficient hRISC occurs only by suppressing internal conversion (IC) from the T n -T 1 state. [23][24][25] The RISC and IC rates are inversely proportional to the T n -S m energy gap. [26] Besides the small T n -S m gap, spin-orbit coupling (SOC) plays a prominent role in determining the RISC rate.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Fast RISC in Hot‐Exciton Thermally Activated Delayed Fluorescence Emitter Through Fused Ring Modification: A Theoretical Insights

Nathiya

2024

Advcd Theory and Sims

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Recent progress has shown promising advancements in enhancing the Reverse intersystem crossing (RISC) process between high‐energy triplet states (Tn, n ≥ 1) and radiative singlet states (Sm) through the utilization of the classic D‐A‐D' strategy. In this study, 12 molecules employing phenyl carbazole and a peripheral phenanthroimidazole as the donors and fused cores as acceptors are theoretically designed. Additionally, electron‐withdrawing groups such as fluorine and cyano, as well as electron‐donating group like methoxy, are incorporated into anthracene, napthaoxadiazole, and napthothiadiazole derivatives, acting as fused core components. Theoretical analyses reveal that among the molecules examined, eight adhere to the three golden principle rules, demonstrating a large energy gap between S1‐T1, the minimal ΔES1‐T2, and large T2‐T1. Additionally, these molecules exhibit significant Spin‐orbit coupling (SOC) and maintain a strong Hybridized local and charge transfer (HLCT) character, facilitating the fast hRISC from T2 to S1. The auxiliary inclusion of heteroatoms, such as oxygen and sulfur, on the anthracene core, aligns with the prerequisite strategy, ultimately reinforcing the SOC. Furthermore, replacing the methoxy group on the Nz bridge significantly enhances the SOC, resulting in a substantial increase in the hRISC rate (10 +08 s−1). Overall, the findings substantially elevate the photophysical attributes of the designed molecules through the utilization of the hRISC channel.

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“…[ 14 ] It is well‐known that hot excitons on high‐lying excited triplet state energy levels can theoretically realize the exciton utilization of 100% by fast reverse intersystem crossing (hRISC) from T n (n≥ 2) to S m (m≥ 1). [ 15 ] Therefore, if using hot exciton materials as EEL, triplet excitons on T n can be utilized directly without the need for collisions of the triplet exciton pairs that leads to additional energy loss. It is expected that the efficiency of TTF‐based blue fluorescence OLEDs can achieve further large enhancement.…”

Section: Introductionmentioning

confidence: 99%

High Efficiency Triplet‐Triplet Fusion Blue Fluorescence OLEDs by introducing a “Hot Exciton” Efficiency Enhancement Layer

Xie,

Wang,

Chen

et al. 2024

Advanced Optical Materials

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Triplet‐triplet fusion (TTF) can effectively transfer triplet excitons to singlet energy level and exhibit good stability, making it widely used in blue fluorescence organic light emitting diodes (OLEDs) for practical application. However, the efficiency of the resulting blue fluorescence OLEDs is still fundamentally limited. Herein, this work introduces a hot exciton efficiency enhancement layer (EEL) between TTF emissive layer and electron‐transporting layer for the first time. It can be found that the triplet excitons are greatly utilized by the efficient hot exciton EEL. As a result, a high efficiency blue fluorescence OLED is successfully developed, exhibiting a maximum external quantum efficiency of 15.2% at the luminance of 4068.0 cd m−2, achieving a breakthrough in the efficiency of blue TTF‐OLEDs. Transient electroluminescence (TrEL) measurements and detailed theoretical calculations confirm the key role of the effective hot exciton process from the high‐lying triplet energy level (Tn, n ≥ 2) to S1 via a reverse intersystem crossing (hRISC). Furthermore, the device lifetime is also greatly improved owing to the fast and efficient hRISC in the introduced hot exciton EEL. This work has important guiding significance for constructing high efficiency blue fluorescence OLEDs by introducing hot exciton molecules.

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Referential tuning strategy for high-lying triplet energy level setting in OLED emitter with hot-exciton characteristics

Abstract: “Hot-exciton” emitters featured with high-lying reverse intersystem crossing (hRISC) has been served as promising candidates due to their meliorative exciton utilization efficiency and efficiency roll-off in organic light-emitting diodes (OLEDs)....

Cited by 6 publications

References 36 publications

Overcoming the Limitation of Spin Statistics in Organic Light Emitting Diodes (OLEDs): Hot Exciton Mechanism and Its Characterization

Overcoming the Limitation of Spin Statistics in Organic Light Emitting Diodes (OLEDs): Hot Exciton Mechanism and Its Characterization

Enhancing Fast RISC in Hot‐Exciton Thermally Activated Delayed Fluorescence Emitter Through Fused Ring Modification: A Theoretical Insights

High Efficiency Triplet‐Triplet Fusion Blue Fluorescence OLEDs by introducing a “Hot Exciton” Efficiency Enhancement Layer

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