Light Emitting Polymermaterials: the Working Base for Flexible Full Color Displays

2003 ◽  
Vol 769 ◽  
Author(s):  
Heinrich Becker ◽  
Esther Breuning ◽  
Arne Büsing ◽  
Aurelie Falcou ◽  
Susanne Heun ◽  
...  
Keyword(s):  
High Efficiency ◽  
Blue Emission ◽  
Current Status ◽  
Light Emitting ◽  
Material Development ◽  
Full Color ◽  
Color Displays ◽  
Operational Lifetime ◽  
Jet Printing ◽  
Efficient Manufacturing

AbstractIn the last few years, industrial research into materials fulfilling the needs of the maturing OLED display industry has intensified considerably. A first generation of polymers (phenyl- PPVs) is now being commercially exploited in first monochrome polymer LED display applications. Based on these materials, non-planar displays have already been demonstrated. However, those proof of concept devices have been monochrome. Especially the RGB materials need considerable improvement to be suitable for flexible full color displays.We will therefore report on the progress in the development of polymers for red, green, and blue emission. Our main focus here is on improving the properties of various polymers derived from the spiro-bifluorene core.Depending on the color, the main issues vary strongly: For BLUE polymers, efficiency, color coordinates, and processibility are already at a commercial level while operational lifetime still needs strong improvement. RED materials are in an almost contrary situation: here, the operational lifetime is excellent, whereas the efficiency and the driving current are requiring further improvement. For GREEN, achieving saturated emission, whilst maintaining the other properties (high efficiency, long operational lifetime), is still challenging. We will demonstrate the current status of material development within Covion.In addition, we achieved advances in full-color patterning, especially techniques based on Ink-Jet printing. This technology potentially allows the efficient manufacturing of high resolution RGB devices on a variety of substrates, including flexible layers.

scholarly journals Operando direct observation of spin-states and charge-trappings of blue light-emitting-diode materials in thin-film devices

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fumiya Osawa ◽  
Kazuhiro Marumoto
Keyword(s):  
Blue Light ◽  
High Performance ◽  
Density Functional ◽  
Light Emitting Diode ◽  
Green Light ◽  
Spin States ◽  
Light Emitting ◽  
Full Color ◽  
Color Displays ◽  
Materials Used

Abstract Spin-states and charge-trappings in blue organic light-emitting diodes (OLEDs) are important issues for developing high-device-performance application such as full-color displays and white illumination. However, they have not yet been completely clarified because of the lack of a study from a microscopic viewpoint. Here, we report operando electron spin resonance (ESR) spectroscopy to investigate the spin-states and charge-trappings in organic semiconductor materials used for blue OLEDs such as a blue light-emitting material 1-bis(2-naphthyl)anthracene (ADN) using metal–insulator–semiconductor (MIS) diodes, hole or electron only devices, and blue OLEDs from the microscopic viewpoint. We have clarified spin-states of electrically accumulated holes and electrons and their charge-trappings in the MIS diodes at the molecular level by directly observing their electrically-induced ESR signals; the spin-states are well reproduced by density functional theory. In contrast to a green light-emitting material, the ADN radical anions largely accumulate in the film, which will cause the large degradation of the molecule and devices. The result will give deeper understanding of blue OLEDs and be useful for developing high-performance and durable devices.

scholarly journals Advances in Quantum-Dot-Based Displays

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1327 ◽  
Author(s):  
Yu-Ming Huang ◽  
Konthoujam James Singh ◽  
An-Chen Liu ◽  
Chien-Chung Lin ◽  
Zhong Chen ◽  
...  
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Flexible Substrate ◽  
Potential Candidate ◽  
White Leds ◽  
Full Color ◽  
Color Displays ◽  
High Illumination ◽  
Coating Methods ◽  
Good Potential

In terms of their use in displays, quantum dots (QDs) exhibit several advantages, including high illumination efficiency and color rendering, low-cost, and capacity for mass production. Furthermore, they are environmentally friendly. Excellent luminescence and charge transport properties of QDs led to their application in QD-based light-emitting diodes (LEDs), which have attracted considerable attention in display and solid-state lighting applications. In this review, we discuss the applications of QDs which are used on color conversion filter that exhibit high efficiency in white LEDs, full-color micro-LED devices, and liquid-type structure devices, among others. Furthermore, we discuss different QD printing processes and coating methods to achieve the full-color micro-LED. With the rise in popularity of wearable and see-through red, green, and blue (RGB) full-color displays, the flexible substrate is considered as a good potential candidate. The anisotropic conductive film method provides a small controllable linewidth of electrically conductive particles. Finally, we discuss the advanced application for flexible full-color and highly efficient QD micro-LEDs. The general conclusion of this study also involves the demand for a more straightforward QD deposition technique, whose breakthrough is expected.

Efficient deep-blue non-doped organic light-emitting diode with improved roll-off of efficiency based on hybrid local and charge-transfer excited state

RSC Advances ◽  
2016 ◽  
Vol 6 (74) ◽  
pp. 70085-70090 ◽  
Author(s):  
Haichao Liu ◽  
Qing Bai ◽  
Weijun Li ◽  
Yachen Guo ◽  
Liang Yao ◽  
...  
Keyword(s):  
Excited State ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Blue Emission ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Deep Blue ◽  
Organic Light ◽  
Slow Roll ◽  
Donor Acceptor

Acceptor–donor–acceptor triphenylamine–phenanthroimidazole derivate (TPA–2PPI) servers as an emitter, whose device exhibits deep-blue emission, high efficiency and slow roll-off of efficiency.

Design of pyridinylphosphinate-based blue iridium phosphors for high-efficiency organic light-emitting diodes

2021 ◽  
Author(s):  
Zheng-Guang Wu ◽  
Bing Yang ◽  
Yu-Chen Qiu ◽  
Yang Wang ◽  
Hong Dai ◽  
...  
Keyword(s):  
Electron Mobility ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Iridium Complexes ◽  
Light Emitting ◽  
Organic Light ◽  
Novel Design

Novel design for iridium complexes merging blue emission and good electron mobility for high-efficiency OLEDs.

High-efficiency new polymer light-emitting diodes with a stabilized blue emission

2005 ◽  
Author(s):  
Sung Heum Park ◽  
Jin Young Kim ◽  
Sun Hee Kim ◽  
Youngeup Jin ◽  
Jinwoo Kim ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Light Emitting ◽  
Polymer Light Emitting Diodes

scholarly journals Full-Color III-Nitride Nanowire Light-Emitting Diodes

2019 ◽  
Vol 3 (4) ◽  
pp. 551 ◽  
Author(s):  
Ravi Teja Velpula ◽  
Barsha Jain ◽  
Ha Quoc Thang Bui ◽  
Hieu Pham Trung Nguyen
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Current Status ◽  
Core Shell ◽  
Nonradiative Recombination ◽  
Carrier Distribution ◽  
Light Emitting ◽  
White Leds ◽  
Full Color

III-nitride nanowire-based light-emitting diodes (LEDs) have been intensively studied as promising candidates for future lighting technologies. Compared to conventional GaN-based planar LEDs, III-nitride nanowire LEDs exhibit numerous advantages including greatly reduced dislocation densities, polarization fields, and quantum-conned Stark effect due to the effective lateral stress relaxation, promising high-efficiency full-color LEDs. Beside these advantages, however, several issues have been identified as the limiting factors for further enhancing the nanowire LED quantum efficiency and light output power. Some of the most probable causes have been identified as due to the lack of carrier confinement in the active region, non-uniform carrier distribution, electron overflow, and the nonradiative recombination along the nanowire lateral surfaces. Moreover, the presence of large surface states and defects contribute significantly to the carrier loss in nanowire LEDs. Consequently, reported nanowire LEDs show relatively low output power. Recently, III-nitride core-shell nanowire LED structures have been reported as the most efficient nanowire white LEDs with a record-high output power which is more than 500 times stronger than that of nanowire white LEDs without using core-shell structure. In this context, we will review the current status, challenges, and approaches for the high-performance IIInitride nanowire LEDs. More specifically, we will describe the current methods for the fabrication of nanowire structures including top-down and bottom-up approaches, followed by characteristics of III-nitride nanowire LEDs. We will then discuss the carrier dynamics and loss mechanism in nanowire LEDs. The typical designs for the enhanced performance of III-nitride nanowire LEDs will be presented next. The color-tunable nanowire LEDs with emission wavelengths in the visible spectrum and phosphor-free nanowire white LEDs will be finally discussed.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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