High-efficiency pure blue thermally activated delayed fluorescence emitters with a preferentially horizontal emitting dipole orientation <i>via</i> a spiro-linked double D–A molecular architecture

Zhang, Xuan; Pan, Kuan-Chung; Lee, Wei‐Kai; Gong, Shaolong; Ni, Fan; Xiao, Xiao; Zeng, Weixuan; Xiang, Yepeng; Zhan, Lisi; Zhang, Yu; Wu, Chung‐Chih; Yang, Chuluo

doi:10.1039/c9tc03582f

Cited by 43 publications

(25 citation statements)

References 52 publications

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“…In 2019, Yang et al further synthesized another TADF molecule (SBA-2DPS) with DPS as electron acceptor and spiro-dicridine (SBA) as electron donor ( Figure 5). [48] SBA-2DPS shows blue TADF characteristic and excellent EL performance. Compared with mono-DMACDPs (named in the original paper as DMAC-1DPS), the molecular length of SBA-2DPS is dramatically longer but the π-conjugation is not extended.…”

Section: The Tadf Molecules With Blue Emissionmentioning

confidence: 94%

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

Che

Xie

2020

Asian J Org Chem

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Owing to the faster response time, wider viewing angle and thinner thickness of organic light emitting diodes (OLEDs) than the conventional displays, the development of high‐efficiency light‐emitting materials has become the focus of attention. In recent years, the TADF materials have aroused widespread attention and experienced rapid development as an emitter in OLEDs, since the maximum internal quantum efficiency can reach 100% theoretically. TADF materials have exhibited the potential to be a low‐cost alternative to expensive phosphorescent luminophors. Whereas, the high resolution displays must endow the characteristics of stable and efficient panchromatic emission. The chemical structure of TADF materials are generally composed of electrical donor and acceptor, the emission colors and efficiency can be adjusted by the charge transfer between them. In this paper, TADF emitters with different emission colors are reviewed, accompanied with the investigation on their molecular design strategies and photophysical properties. In addition, the development direction and application of TADF materials are prospected.

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Section: The Tadf Molecules With Blue Emissionmentioning

confidence: 94%

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

Che

Xie

2020

Asian J Org Chem

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“…Later in 2019, Yang and co‐workers published the blue TADF emitter SBA2DPS as displayed in Figure 12, which performed in the respective OLED with an EQE of 25.5%, an EL wavelength of 467 nm, and CIE coordinates of (0.15, 0.20). [ 116 ] They stated that its high EQE is superior to most reported TADF devices with a CIE y‐coordinate below (0.20).…”

Section: Emitters For Application In Oledsmentioning

confidence: 99%

A Brief History of OLEDs—Emitter Development and Industry Milestones

et al. 2021

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Organic light‐emitting diodes (OLEDs) have come a long way ever since their first introduction in 1987 at Eastman Kodak. Today, OLEDs are especially valued in the display and lighting industry for their promising features. As one of the research fields that equally inspires and drives development in academia and industry, OLED device technology has continuously evolved over more than 30 years. OLED devices have come forward based on three generations of emitter materials relying on fluorescence (first generation), phosphorescence (second generation), and thermally activated delayed fluorescence (third generation). Furthermore, research in academia and industry toward the fourth generation of OLEDs is in progress. Excerpts from the history of green, orange‐red, and blue OLED emitter development on the side of academia and milestones achieved by key players in the industry are included in this report.

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“…Similar results have been obtained by a number of other groups in both neat films and host-guest systems. [20,23,38,40,41,[45][46][47][48][49][52][53][54]76,77,105] From these studies, it has become a widely accepted dogma in the field that more extended molecules promote horizontal orientation of emitters, thereby increasing the outcoupling efficiency of devices. This improved orientation is often attributed to an increased aspect ratio of the molecules (higher linearity or planarity).…”

Section: Molecular Shapementioning

confidence: 99%

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

et al. 2021

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In organic light‐emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass‐transition temperature (Tg) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state‐of‐the‐art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum‐processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta‐analysis of 203 published emitter systems is conducted and combined with density‐functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host–guest systems with low‐MW emitters, orientation is mostly influenced by the host Tg, whereas the length and MW of the emitter become more relevant for systems involving higher‐MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.

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High-efficiency pure blue thermally activated delayed fluorescence emitters with a preferentially horizontal emitting dipole orientation via a spiro-linked double D–A molecular architecture

Abstract: A spiro-linked double D–A molecular architecture has been introduced to construct blue thermally activated delayed fluorescence (TADF) emitters with a preferentially horizontal emitting dipole orientation.

Cited by 43 publications

References 52 publications

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

Structural Design of Blue‐to‐Red Thermally‐Activated Delayed Fluorescence Molecules by Adjusting the Strength between Donor and Acceptor

A Brief History of OLEDs—Emitter Development and Industry Milestones

Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light‐Emitting Diodes

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