Breaking the Efficiency Limit of Fluorescent OLEDs by Hybridized Local and Charge-Transfer Host Materials

Chen, Lingfeng; Zhang, Shitong; Li, Hui; Chen, Runfeng; Jin, Lu; Yuan, Kai; Li, Huanhuan; Lü, Ping; Yang, Bing; Huang, Wei

doi:10.1021/acs.jpclett.8b02138

Cited by 81 publications

(51 citation statements)

References 31 publications

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“…The fundamental challenges associated with the fabrication of electroluminescent devices are structure optimization and material characterization leading to higher luminance, low turn‐on voltage, high stability, high current efficiency, and external quantum efficiency. Recently, OLEDs have achieved commercialization in displays and solid‐state lightings . Due to the complex evaporation deposition procedures for multilayer devices, it is of great importance to understand the interfacial behaviors in the OLEDs.…”

Section: Is Study For Electroluminescent Devicesmentioning

confidence: 99%

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

Ali

Chang

Imran

et al. 2019

Physica Rapid Research Ltrs

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Solution‐processed optoelectronic devices based on conjugated polymers, colloidal quantum dots (CQDs), halide perovskites, and so on are now emerging as a new‐generation semiconductor technology which prevails its conventional counterparts in terms of low fabrication cost, ease of scalable manufacturing, and abundant material designability. However, the solution‐processed thin films obtained through spin‐coating, spray, inkjet printing, and doctor blading usually suffer from low film quality and a high defect density especially at the interfaces of different functional layers. Currently, the most significant subject is to address the non‐ideal interfaces for achieving improved performance of the devices. Impedance spectroscopy (IS) is a universal technique that can help to examine the charge behavior at the interfaces in an electrochemical or solid‐state multilayered device. Owing to its ability to elucidate the charge transfer, charge transport, and accumulation within the interfaces of electrochemical or multilayered devices with minimal effects to the devices themselves, the use of IS has increased vividly in the last decades. This review provides the basic principles of IS and its applications on solution‐processed optoelectronic devices.

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Section: Is Study For Electroluminescent Devicesmentioning

confidence: 99%

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

Ali

Chang

Imran

et al. 2019

Physica Rapid Research Ltrs

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show abstract

“…14,15 Given the fact that the HLCT concept was proposed a few years ago, to date the development of HLCT emitters still lags behind TADF emitters. [16][17][18] In particular, device performances of most HLCT-based OLEDs remain restricted as their external quantum efficiencies (EQEs) are generally <10%, 10,15,[19][20][21][22][23] leaving much room for efficiency improvement. Seen in this light, there is an urgent need for simple and effective strategies to develop high-efficiency HLCT emitters and related OLEDs.…”

Section: Introductionmentioning

confidence: 99%

Hybridized Local and Charge-Transfer Excited-State Fluorophores through the Regulation of the Donor–Acceptor Torsional Angle for Highly Efficient Organic Light-Emitting Diodes

Chen

Liu

et al. 2022

CCS Chem

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Hybridized local and charge-transfer (HLCT) excited-state fluorophores, which enable full exciton utilization through a reverse intersystem crossing from high-lying triplet states to singlet state, have attracted increasing attention toward organic light-emitting diodes (OLEDs) application. Herein, we report three D-π-A-π-D-type isomers o-2CzBT, m-2CzBT, and p-2CzBT by adjusting the donor (D) units from ortho-, meta-, to para-substituted positions with the acceptor (A) core unit, respectively. The HLCT properties of the three compounds are evidently confirmed by theoretical calculations, solvatochromic behaviors, and transient decay lifetimes analyses. As the substituted position changes from the ortho-, meta-, and para-positions, the reduced steric hindrance brings about decreased torsional angle between D and A moieties, resulting in increased oscillator strength. Accordingly, the para-substituted p-2CzBT is endowed with a more locally excited component that accounts for faster radiative decay, leading to a higher fluorescent efficiency than that of o-2CzBT and m-2CzBT. As expected, p-2CzBT enables its nondoped and doped OLEDs with higher external quantum efficiencies (EQEs) of 12.3% and 15.0%, respectively, which are among the state-of-the-art efficiencies of HLCT-based OLEDs. Moreover, o-2CzBT and m-2CzBT are also utilized as host materials for high-performance OLEDs, thus extending the application of HLCT materials.

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“…Insertion of electron‐transporting DFH‐4T material in between the electron injecting and emissive (TPTQF‐C) layers assisted in widening the recombination zone across the whole channel with enhanced brightness of 2933 nW (Figure 22d,e). Further, this modified device architecture delivered a better EQE of 6.9% that can be comparable with fluorescent OLED (∼5%) [ 143 ] , divulging the significance of charge‐transporting layers in enhancing the device performance. The authors in their recent work replaced the carbazole donor in TPTQ‐C with fluorene donor to form TPTQ‐F that exhibited enhanced planarity with an interchain π−π distance of 4.0 Å contributing to a high photoluminescence efficiency of 77%.…”

Section: Progress Of Olet Toward Display Applicationsmentioning

confidence: 99%

En Route to Wide Area Emitting Organic Light‐Emitting Transistors for Intrinsic Drive‐Integrated Display Applications: A Comprehensive Review

Ganesan

Tsao

Gao

2021

Adv Funct Materials

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Organic light-emitting transistors (OLET) evolved from the fusion of the switching functionality of field-effect transistors (FET) with the light-emitting characteristics of organic light-emitting diode (OLED) that can simplify the active-matrix pixel device architecture and hence offer a promising pathway for future flat panel and flexible display technology. This review systematically analyzes the key device/molecular engineering tactics that assist in improving the electrode edge narrow emission to wide-area emission for display applications via three different topics, that is, narrow to wide-area emission, vertical architecture, and impact of high-κ dielectric on the device performance. Source-drain electrode engineering such as symmetric/asymmetric, planar/ non-planar arrangement, semitransparent nature, multilayer approach comprising charge transport, and work function modification layers enable widening the emission zone. Vertical OLET architecture offers short channel lengths with a high aperture ratio, pixel type area emission, and stable lightemitting area. Transistors utilizing high-κ dielectric materials have assisted in lowering the operating voltage, enhancing luminance and air stability. The promising development in achieving wide-area emission provides a solid basis for constructing OLET research toward display applications; however, it relies on developing highly luminescent and fast charge transporting materials, suitable semitransparent source/drain electrodes, high-κ -dielectrics, and device architectural engineering.

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Breaking the Efficiency Limit of Fluorescent OLEDs by Hybridized Local and Charge-Transfer Host Materials

Cited by 81 publications

References 31 publications

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

Hybridized Local and Charge-Transfer Excited-State Fluorophores through the Regulation of the Donor–Acceptor Torsional Angle for Highly Efficient Organic Light-Emitting Diodes

En Route to Wide Area Emitting Organic Light‐Emitting Transistors for Intrinsic Drive‐Integrated Display Applications: A Comprehensive Review

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