Purely organic materials for extremely simple all-TADF white OLEDs: a new carbazole/oxadiazole hybrid material as a dual-role non-doped light blue emitter and highly efficient orange host

Zhang, Di; Cao, Xudong; Wu, Qingjing; Zhang, Mucan; Sun, Ning; Zhang, Xianping; Tao, Youtian

doi:10.1039/c7tc04969b

Cited by 71 publications

(48 citation statements)

References 35 publications

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“…show promising thermal stability and electron injection and transporting properties. 50,[52][53][54][55][56][57] Lastly, according to theoretical calculations, the LUMO density of 2CzPN is mostly located on the central benzene ring 15 whereas that of oxadiazole is located on the heterocyclic ring (vide infra). 50,54 This implies that the electron density of the HOMO, which in this study is localized on the carbazole units, and LUMO in the oxadiazole derivatives should be more chloride of choice to provide the desired oxadiazole emitters in good yield (38-75%).…”

Section: Introductionmentioning

confidence: 99%

Deep-Blue Oxadiazole-Containing Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes

Wong

Krotkus

Copley

et al. 2018

ACS Appl. Mater. Interfaces

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A series of four novel deep-blue to sky-blue thermally activated delayed fluorescence (TADF) emitters (2CzdOXDMe, 2CzdOXD4MeOPh, 2CzdOXDPh, and 2CzdOXD4CFPh) have been synthesized and characterized. These oxadiazole-based emitters demonstrated bluer emission compared with the reference emitter 2CzPN thanks to the weaker acceptor strength of the oxadiazole moieties. The oxadiazole compounds doped in hosts (mCP and PPT) emitted from 435 to 474 nm with photoluminescence quantum yields ranging from 14-55%. The emitters possess singlet-triplet excited-state energy gaps (Δ E) between 0.25 and 0.46 eV resulting in delayed components ranging from 4.8 to 25.8 ms. The OLED device with 2CzdOXD4CFPh shows a maximum external quantum efficiency of 11.2% with a sky-blue emission at CIE of (0.17, 0.25), while the device with 2CzdOXD4MeOPh shows a maximum external quantum efficiency of 6.6% with a deep-blue emission at CIE of (0.15, 0.11).

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Section: Introductionmentioning

confidence: 99%

Deep-Blue Oxadiazole-Containing Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes

Wong

Krotkus

Copley

et al. 2018

ACS Appl. Mater. Interfaces

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“…As a consequence, only low efficiency can be attained at high luminances, which is not beneficial to the practical applications. To loosen this bottleneck, the charge balance, energy barriers between nearby layers, and materials selection should be well manipulated [72][73][74][75][76]. With the endeavor of academic and industrial researchers to enhance the materials design and device engineering, we believe that WOLEDs with TADF emitters can play a significant role in the marketplace in the near future, which is beneficial to our human society.…”

Section: Discussionmentioning

confidence: 99%

White Organic Light-Emitting Diodes with Thermally Activated Delayed Fluorescence Emitters

Luo¹,

He²,

Xiao³

et al. 2018

Light-Emitting Diode - An Outlook on the Empirical Features and Its Recent Technological Advancements

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Recently, thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have attracted both academic and industrial interest due to their extraordinary characteristics, such as high efficiency, low driving voltage, bright luminance, lower power consumption, and potentially long lifetime. In this chapter, various approaches to realize white OLEDs (WOLEDs) with TADF emitters have been introduced. The recent development of WOLEDs based on all TADF emitters, WOLEDs based on TADF and conventional fluorescence emitters, and WOLEDs based on TADF and phosphorescence emitters is highlighted. Particularly, the device structures, design strategies, working mechanisms, and electroluminescent processes of the representative high-performance WOLEDs with TADF emitters are reviewed. Moreover, challenges and opportunities for further enhancement of the performance of WOLEDs with TADF emitters are presented.

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“…This was further improved upon embedding of the emitter into a host at 40 wt % to 28 % EQE . Replacing the nitrile groups by the less electron‐withdrawing oxadiazole units with weaker acceptor strength results in a bluer emission and promising thermal and electron transport properties as predicted by advanced theoretical calculations …”

Section: Introductionmentioning

confidence: 94%

Acceptor Derivatization of the 4CzIPN TADF System: Color Tuning and Introduction of Functional Groups

et al. 2019

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We demonstrate modular modifications of the widely employed emitter 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) by replacing one or both nitrile acceptors with oxadiazole groups via a tetrazole intermediate. This allows the introduction of various functional groups including halides, alkynes, alkenes, nitriles, esters, ethers and a protected amino acid while preserving the thermally activated delayed fluorescence (TADF) properties. The substituents control the emission maximum of the corresponding emitters, ranging between 472-527 nm, and show high solid-state photoluminescence quantum yields up to 85 %. The TADF emission of two compounds, 4CzCNOXDtBu and 4CzdOXDtBu, a mono-and a bis-oxadiazole substituted 4CzIPN is characterized in detail by time-and temperaturedependent photoluminescence. Solution-processed OLEDs comprising 4CzCNOXDtBu and 4CzdOXDtBu show a significant blue-shift of the emission compared to the reference 4CzIPN, with external quantum efficiencies of 16 %, 5.9 % and 17 % at 100 cd m À 2 , respectively.

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Purely organic materials for extremely simple all-TADF white OLEDs: a new carbazole/oxadiazole hybrid material as a dual-role non-doped light blue emitter and highly efficient orange host

Abstract: Extremely simple two-color all-TADF WOLEDs with a single-emissive-layer singe-host/dopant system provide a bright future for high-efficiency low-cost vacuum-deposited WOLEDs.

Cited by 71 publications

References 35 publications

Deep-Blue Oxadiazole-Containing Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes

Deep-Blue Oxadiazole-Containing Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes

White Organic Light-Emitting Diodes with Thermally Activated Delayed Fluorescence Emitters

Acceptor Derivatization of the 4CzIPN TADF System: Color Tuning and Introduction of Functional Groups

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