Tandem Organic Light‐Emitting Diodes

Fung, Man‐Keung; Li, Yanqing; Liao, Liang‐Sheng

doi:10.1002/adma.201601737

Cited by 150 publications

(100 citation statements)

References 144 publications

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“…Organic light emitting devices (OLEDs) are popular for activeluminescent displays and lighting technologies, owing to their special features, such as easy processing, light weight, exibility, commercial viability etc. [1][2][3][4][5][6][7][8][9][10][11][12] For white light, emission of primary colours (RGB) or a broad visible-light spectrum is vital. Several strategies have been reported by various groups to obtain white light ( Fig.…”

Section: Introductionmentioning

confidence: 99%

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

et al. 2019

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Materials showing white light emission have found applications in a variety of solid state devices especially in display technology. For white light emission, doping of red (R), green (G) and blue (B) emitters in a host matrix is commonly practised. However, finding RGB emitters of similar stability with homogenous doping is challenging. Furthermore, such devices suffer from color purity in the long run. Small organic light emitters, capable of colour tuning and having a broad emission spectrum are in high demand as they provide colour stability, reproducibility, a simple device geometry and high efficiency. Recently, it has been shown that the efficiency of OLEDs can be enhanced by employing thermally activated delayed fluorescence (TADF) materials. Here, we designed and synthesised a xanthone-carbazole based D-A-D material (Xan-Cbz) for TADF properties. Blue TADF emission, in neat thin films, at 470 nm was observed and further investigated by studying delayed fluorescence and lifetime measurements. In addition, a blend of Xan-Cbz with NPD shows exciplex emission at 525 nm in thin film. OLEDs based on Xan-Cbz were fabricated using several device configurations. OLEDs having the device configuration ITO/PEDOT:PSS/NPD/Xan-Cbz/Bphen/LiF-Al showed a luminance of 1.96 Â 10 4 Cd m À2 (at a current density of 50 mA cm À2 ) and V ON at $6 V. Electroluminescence showed the features of both neat emission (470 nm) of Xan-Cbz and its exciplex (525 nm) with NPD. Further, colour tuning was observed as a function of applied voltage and the ratio of light intensity (I 525 /I 470 ) of neat and exciplex emission was found to decrease with increasing voltage. Greenish-blue emission (CIE coordinates: 0.202, 0.382) from Xan-Cbz OLEDs was obtained. Xan-Cbz showed its neat emission (at 470 nm) in ITO/PEDOT:PSS/ CBP/Xan-Cbz/Bphen/LiF-Al and pure exciplex emission (at 525 nm) in ITO/PEDOT:PSS/NPD:Xan-Cbz/ Bphen/LiF-Al device configurations. Thus in this article we showed blue TADF emission, exciplex emission and voltage dependent color tuning in OLEDs based on a small organic emitter.

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Section: Introductionmentioning

confidence: 99%

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

et al. 2019

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“…Obviously, the typical device with simple sandwiched layer structure cannot meet the requirements. Although there have been many reviews about the device structures of OLED, especially in tandem and white device,– more novel device structures should be proposed, and deeper understanding about device working mechanism should be explored.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Organic Electroluminescence: Design from Organic Light‐Emitting Materials to Devices

Tao

Miao

Wang

et al. 2018

The Chemical Record

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Organic electroluminescence is considered as the most competitive alternative for the future solid-state displays and lighting techniques owing to many advantages such as selfluminescence, high efficiency, high contrast, high color rendering index, ultra-thin thickness, transparency, flat and flexibility, etc. The development of high-performance organic electroluminescence has become the continuing focus of research. In this personal account, a brief overview of representative achievements in our study on the design of highly efficient novel organic light-emitting materials (including fluorescent materials, phosphorescent iridium(III) complexes and conjugated polymers bearing phosphorescent iridium(III) complex) and highperformance device structures together with working principles are given. At last, we will give some perspectives on this fascinating field, and also try to provide some potential directions of research on the basis of the current stage of organic electroluminescence. Wiley Online Library 1537 Scheme 5. The chemical structures of cationic iridium(III) complexes based on various N N ligands (18-23).Figure 7. UV-vis absorption (a) and PL (b) of 18-23 in CH 2 Cl 2 . [30] Figure 35. (a) The device structure and proposed working mechanism for WOLED with sandwiched blue EML; (b) The normalized EL spectra of WOLED at the voltage of 5-7 V, and corresponding luminance, CIE, CCT, and CRI are also given. [65a]

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“…In recent years, OLEDs have received plenty of attention and been widely studied for next-generation solid-state lighting and displays due to their desirable features. [1][2][3][4][5][6][7][8] OLEDs have a huge potential to be the next-generation light source, as they are thin, eco-friendly in terms of energy consumption and use of organic materials, easy to fabricate due to solution processability, and flexible, even stretchable so it can be bent into different shapes. Also, it offers other distinct features, such as UV/IR/glare free, color tunability, and a high color rendering index.…”

Section: Introductionmentioning

confidence: 99%

Smart OLED Lighting on Electrochromic Glass

Liu

et al. 2018

Physica Status Solidi (a)

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Smart organic light‐emitting diodes (OLEDs) prepared on poly(3,4‐ethylenedioxythiophene) (PEDOT)‐based electrochromic glass is demonstrated for the first time. In this work, electrochromic glass based on PEDOT is adopted as a substrate for OLED and used for tuning the light‐emitting direction. The color of the glass changes from pale blue to dark blue upon the application of an external voltage. The coloration or discoloration is due to reaction of the redox solution with PEDOT. Therefore, the utilization of this coloration or discoloration of the glass substrate can adjust the light‐emitting direction of OLED. When the glass is tuned to semi‐transparent, it causes the dual‐side emitting device to display a graceful spatial impression. When the glass becomes highly opaque, the device exhibits top emission with a significantly enhanced luminance efficiency, in which the current efficiencies can be increased twice compared with those when the smart glass was switched off. For the green device, the current efficiency increases from 9.5 to 19.0 cd A−1. For the white device, it increases from 7.5 to 15.5 cd A−1. The authors believe that the combination of smart glass and OLED is a new concept for future OLED lighting applications.

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Tandem Organic Light‐Emitting Diodes

Cited by 150 publications

References 144 publications

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

TADF and exciplex emission in a xanthone–carbazole derivative and tuning of its electroluminescence with applied voltage

High‐Performance Organic Electroluminescence: Design from Organic Light‐Emitting Materials to Devices

Smart OLED Lighting on Electrochromic Glass

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