Exceeding 30 % External Quantum Efficiency in Non‐doped OLEDs Utilizing Solution Processable TADF Emitters with High Horizontal Dipole Orientation via Anchoring Strategy

Zhao, Guimin; Liú, Dan; Wang, Panpan; Huang, Xin-Lin; Chen, Haowen; Zhang, Yuewei; Zhang, Dongdong; Jiang, Wei; Sun, Yueming; Duan, Lian

doi:10.1002/anie.202212861

Cited by 65 publications

(25 citation statements)

References 96 publications

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“…showed that by attaching flexible chains with terminal 9,9′‐spirobi[fluorene] (HSF) units to a known TADF emitter core can contribute to a more horizontal orientation of the TDM by increasing the effective planarity of the compound [19d] . The TDM of 5CzBN‐HSF is 72 % horizontally oriented in the neat film, while the referencing compound, 5CzBN‐Hex (without HSF units), possesses an isotropically orientated TDM [19d] . These studies opened a new horizon for the use of liquid crystalline materials in OLEDs, especially in terms of the tuning of the film morphology and molecular orientation.…”

Section: Introductionmentioning

confidence: 99%

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

et al. 2023

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The use of thermally activated delayed fluorescence (TADF) emitters and emitters that show preferential horizontal orientation of their transition dipole moment (TDM) are two emerging strategies to enhance the efficiency of OLEDs. We present the first example of a liquid crystalline multi-resonance TADF (MR-TADF) emitter, DiKTa-LC. The compound possesses a nematic liquid crystalline phase between 80 °C and 110 °C. Importantly, the TDM of the spin-coated film shows preferential horizontal orientation, with an anisotropy factor, a, of 0.28, which is preserved in doped poly(vinylcarbazole) films. Green-emitting (λ EL = 492 nm) solution-processed OLEDs based on DiKTa-LC showed an EQE max of 13.6 %. We thus demonstrate for the first time how self-assembly of a liquid crystalline TADF emitter can lead to the so-far elusive control of the orientation of the transition dipole in solutionprocessed films, which will be of relevance for highperformance solution-processed OLEDs.

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Section: Introductionmentioning

confidence: 99%

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

et al. 2023

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“…Another point needed to think about is that, in contrast to vacuum evaporation, solution process is expected to be a promising technology for large‐area commercial production, which puts forward higher requirements for the solubility and film‐forming ability of the corresponding materials. [ 22–26 ] Hence, how to design suitable solution‐processed TADF regioisomers and dissect the inner structure‐properties relationship is more urgent for enriching solution‐processed OLEDs.…”

Section: Introductionmentioning

confidence: 99%

“…Clearly analyzing the relationship between structure which puts forward higher requirements for the solubility and film-forming ability of the corresponding materials. [22][23][24][25][26] Hence, how to design suitable solution-processed TADF regioisomers and dissect the inner structure-properties relationship is more urgent for enriching solution-processed OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Regioisomeric Engineering to Optimize the Characteristics of TADF Emitters for High‐Performance Solution Processable Organic Light Emitting Diodes

Zhao

Zhou

Zhang

et al. 2023

Advanced Optical Materials

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and performance of isomers also makes for understanding the laws of abundant material structures in nature. The most popular example of this is that adamas, graphite, and footballene are all made of carbon element but highlight different functions. The primary reason of different physical properties and utilization of adamas, graphite, and footballene lies in that the carbon atoms are differently arranged. Hence, the exploration of multifunctional isomers could fully release the potential of the molecular skeleton and make full use of architectural feature.Accompanied by the surging demand in flexible display and illumination fields, except for natural daylight, organic lightemitting diodes (OLEDs) have shown great allure in view of bringing more creative display and aesthetic design. [6][7][8][9][10] In order to satisfy the iteratively updated usage requirement and maximize exciton utilization efficiency, thermally activated delayed fluorescence (TADF) materials, taking over from trad fluorescence and phosphorescence emitters, have been considered as the third-generation electroluminescent materials applied in OLEDs. [11][12][13][14][15] Since the advent of TADF, there have been many molecular design or modification strategies for achieving high-performance OLEDs, on one hand, which promotes the development TADF materials, on the other hand, but brings a complex process of exploration and analysis. Imagine that using only one molecular skeleton to explore the effect of modification of the same substituent in different positions, namely regioisomerism, [16][17][18] on its photoelectric properties, contributes to picking the most suitable material to maximize the potential of the molecular skeleton. (2s,3r,4r)-2,3,4,5,6-penta(9H-carbazol-9-yl)benzonitrile (5CzBN) with merits of a 3D molecular structure and high photoluminescence quantum yield (PLQY), has been a frequently used TADF emitter. [19][20][21] As shown in Figure 1, multiple substitution sites on carbazole groups could represent various electronegativity, charge transfer process, molecular stacking, and so on. Therefore, appropriate group substituted at different sites is expected to unfold interesting and varied photoelectric properties. Another point needed to think about is that, in contrast to vacuum evaporation, solution process is expected to be a promising technology for large-area commercial production, Nimble utilization of the regioisomerism concept plays an important role in organic optoelectronic field to exploit high-performance materials in a concise way. However, the relationship between the binding mode and molecular property is still short of explicit understanding and it impedes the creation of desirable materials efficiently. Herein, we report three regioisomeric emitters with obvious thermally activated delayed fluorescence (TADF) and aggregation-induced emission characteristics when multiple flexible dendrons are bonded to the different substituted position of carbazole groups (C2/C3/C4) through ether bond. Bonding positions are close...

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“…In recent times, significant experimental efforts have been made to capitalize on higher EQE of over 30.7% by in-silico design of molecular configurations and device fabrications. 31,32 Nevertheless, the higher performance of TADF-based organic-light emitting devices and an in-depth understanding of material properties based on the features representing the generalized model still need to be improved. Therefore, a design principle with good descriptors is a prerequisite to enhance the modeling of TADF materials for efficiency enhancement.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analyses of Data Driven Machine Learning Models for TADF Emitters

Bhattacharyya

2023

Preprint

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Thermally activated delayed fluorescence (TADF) chromophores have attracted significant attention because they can harvest singlets and triplets in organic light-emitting diodes (OLEDs), resulting in high external quantum efficiency (EQE). This work aims to use a data-driven machine-learning model to predict the relationship between EQE and essential features of TADF-based OLEDs. The study uses a set of experimental data and applies various machine-learning models to analyze the relationship between EQE and the features of the device. The Random Forest model is found to have the highest accuracy for predicting EQE for non-doped TADF emitters. The importance of feature selection and its correlation with EQE is also analyzed, providing insight into how to select the best machine-learning model for rapid material screening and device optimization for non-doped TADF materials.

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Exceeding 30 % External Quantum Efficiency in Non‐doped OLEDs Utilizing Solution Processable TADF Emitters with High Horizontal Dipole Orientation via Anchoring Strategy

Cited by 65 publications

References 96 publications

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

Mesogenic Groups Control the Emitter Orientation in Multi‐Resonance TADF Emitter Films**

Regioisomeric Engineering to Optimize the Characteristics of TADF Emitters for High‐Performance Solution Processable Organic Light Emitting Diodes

Comparative Analyses of Data Driven Machine Learning Models for TADF Emitters

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