Search query: Light-emitting-diodes based on conjugated polymers

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abstract: CONJUGATED polymers are organic semiconductors, the semiconducting behaviour being associated with the p molecular orbitals delocalized along the polymer chain. Their main advantage over non polymeric organic semiconductors is the possibility of processing the polymer to form useful and robust structures. The response of the system to electronic excitation is nonlinear the injection of an electron and a hole on the conjugated chain can lead to a self localized excited state which can then decay radiatively, suggesting the possibility of using these materials in electroluminescent devices. We demonstrate here that poly(p phenylene vinylene) prepared by way of a solution processable precursor, can be used as the active element in a large area light emitting diode. The combination of good structural properties of this polymer, its ease of fabrication, and light emission in the green yellow part of the spectrum with reasonably high efficiency, suggest that the polymer can be used for the development of large area light emitting displays.
author_names: Jeremy H Burroughes

Donal D C Bradley

A Robinson Brown

R N Marks

K Mackay

Richard H Friend

P L Burns

Andrew B Holmes
title: Light emitting diodes based on conjugated polymers
venue: Nature
year: 1990

abstract: Nature 347, 539 541 (1990) IN the published version of this paper the name of one of the authors was incorrectly cited as P. L. Burns rather than P. L. Burn. His address is the University Chemical Laboratory, Cambridge, rather than the University Chemistry Laboratory as stated. GUIDE TO AUTHORS Please follow these guidelines so thatyoui be handled expeditiously.
author_names: Jeremy H Burroughes

Donal D C Bradley

A Robinson Brown

R N Marks

K Mackay

Richard H Friend

Paul L Burn

Andrew B Holmes
title: Light emitting diodes based on conjugated polymers
venue: Nature
year: 1990

abstract: Wide range low voltage continuous color tuning is achieved in multilayer light emitting diodes based exclusively on the commonly used high efficiency electroluminescent conjugated polymers. There are three layers for red, green, and blue emission, and one extra layer for electron blocking. The color of the emitted photon depends on the position of the electron hole recombination. Due to the stronger field dependence of the electron mobility relative to the hole mobility, the recombination zone is pushed away from the cathode and concentrated in different emissive layers as the voltage increases.
author_names: C C Huang

Hsin-Fei Meng

G K Ho

Chiou-Feng Chen

Chian-Shu Hsu

Jian-Ming Huang

Sheng-Fu Horng

Boyu Chen

L C Chen
title: Color tunable multilayer light emitting diodes based on conjugated polymers
year: 2004

abstract: A series of random conjugated copolymers PFCFS1 20 with 2,5 diphenyl 3,4 bis(3 fluorophenyl) silole (fluorinated TPS) chemically doped in 2,7 fluorene 2,7 carbazole main chain were successfully synthesized and characterized. Polymers PFCFS1 20 with fluorinated TPS contents from 1 to 20 possess high weight average molecular weights between 63.5 and 114.1 kg mol 1. The absorption spectra of THF solutions and films of PFCFS1 20 are very similar, showing peaks around 385 nm and optical band gaps around 2.87 eV. Almost no red shifts of the absorption peaks from a solution to a solid state film for the four copolymers indicate that their interchain interactions are extremely weak. PFCFS1 20 solutions show blue emissions with very limited intrachain excitation energy transfers. The films of PFCFS1 20 also display blue emissions with main peaks at 449 nm for PFCFS1 and 475 nm for PFCFS20, suggesting that the fluorinated TPS may comprise more twisted phenyl peripherals. Two types of electroluminescence (EL) devices with configurations of ITO/PEDOT:PSS/PFCFS/CsF/Al and ITO/PEDOT:PSS/PFCFS/TPBI/CsF/Al were investigated. It was found that PFCFS1 20 in the two types of EL devices could show blue to sky blue emissions. Among PFCFS1 20, for EL devices without TPBI layer, PFCFS5 possesses the best device performances with maximum luminous efficiency (LEmax) of 1.46 cd A 1 and maximum external quantum efficiency (EQEmax) of 0.93 The insertion of TPBI as the electron transport layer remarkably improves the EL performances. Also PFCFS5 displays the best LEmax of 4.59 cd A 1 and EQEmax of 3.21 The latter one is among the best efficiency so far reported for silole containing polymers. Our results suggest that the fluorinated TPS is an efficient chromophore for constructions of blue emissive conjugated polymers.
author_names: Lianjie Zhang

Zhulin Liu

Xiaofei Zhang

Junwu Chen

Yong Cao
title: Efficient Blue Light Emitting Diodes Based on Conjugated Polymers with Fluorinated Silole Chemically Doped in Fluorene Carbazole Main Chain
venue: Journal of Inorganic and Organometallic Polymers and Materials
year: 2014

author_names: Paul L Burn

Andrew B Holmes

Arno Kraft

A Robinson Brown

Donal D C Bradley

Richard H Friend
title: Light Emitting Diodes Based on Conjugated Polymers: Control of Colour and Efficiency
year: 1992

author_names: Changyun Jiang

Wei Yang

Junbiao Peng

Steven Shuyong Xiao

Yong Cao
title: High Efficiency, Saturated Red Phosphorescent Polymer Light Emitting Diodes Based on Conjugated and Non Conjugated Polymers Doped with an Ir Complex
year: 2004

abstract: Abstract A series of blue light emitting conjugated polymers based on electron donating trifluoren 2 ylamine and electron deficient dibenzothiophene S,S dioxide were synthesized via typical Suzuki coupling reactions. Their thermal, photophysical and electrochemical properties were fully studied. Owing to the excellent thermal stability, film forming ability as well as the favorable energy levels of the polymers, highly efficient non doped single layer blue devices by using these polymers as an emitting layer (EML) were achieved. Among them, the device based on PSFOFN1 showed the highest maximum current efficiency (CEmax) of 1.99 cd/A. Moreover, the device presented small efficiency roll off with current efficiency (CE) of 1.97 cd/A at high brightness up to 100 cd/m2. In addition, the Commission Internationale de L'Eclairage (CIE) coordinates of all the devices are very close to the deep blue region. Our findings suggest the potential applications of the polymers in full color flat panel displays and organic lighting.
author_names: Hua Ye

Baofeng Zhao

Dongyun Li

Dongcheng Chen

Gaozhan Xie

Shi-Jian Su

Wei Yang

Yong Cao
title: Highly efficient non doped single layer blue organic light emitting diodes based on light emitting conjugated polymers containing trifluoren 2 ylamine and dibenzothiophene S,S dioxide
year: 2015

abstract: Since the first attempt that was made to obtain direct circularly polarized (CP) light from OLEDs by Meijer et al. in 1997, considerable efforts have been devoted to the development of circularly polarized organic light emitting diodes (CP OLEDs) particularly in the recent years. Circularly polarized electroluminescence (CPEL) based on OLEDs has attracted increasing interest for its efficient ability to generate CP light directly and wide potential applications in 3D displays, optical data storage, and optical spintronics. In this review, we systematically summarize the recent progress in chiral emitter based OLEDs with CPEL properties including CPEL based on chiral conjugated polymers, CPEL based on chiral metal complexes, and CPEL based on chiral simple organic molecules, especially chiral thermally activated delayed fluorescence (TADF) molecules. We believe that this review will provide a promising perspective of chiral emitter based OLEDs with CPEL properties for a broad range of scientists in different disciplinary areas and attract a growing number of researchers to this fast growing research field.
author_names: Da-Wei Zhang

Meng Li

Chuan-Feng Chen
title: Recent advances in circularly polarized electroluminescence based on organic light emitting diodes.
venue: Chemical Society reviews
year: 2020

abstract: White light emitting diodes (LEDs) were fabricated using GaN based 380 nm UV LEDs precoated with the composite of blue emitting polymer (poly[(9,9 dihexylfluorenyl 2,7 diyl) alt co (2 methoxy 5 {2 ethylhexyloxy) 1 ,4 phenylene) yellow green emitting polymer (poly[(9,9 dioctylfluorenyl 2,7 diyl) co (1,4 benzo {2,1',3} thiadiazole) and 605 nm red emitting quantum dots (QDs) CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM) and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three band white light was generated by hybridizing blue (430 nm) green (535 nm) and red (605 nm) emission. The color rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE 1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368) 3969 K, and 90, respectively.
author_names: Hyunchul Jung

Wonkeun Chung

Chang Hun Lee

Sung Hyun Kim
title: Fabrication of white light emitting diodes based on UV light emitting diodes with conjugated polymers (CdSe/ZnS) quantum dots as hybrid phosphors.
venue: Journal of nanoscience and nanotechnology
year: 2012

abstract: Abstract We report the use of green and blue fluorene conjugated polymers doped with hole transport materials consisting of triarylamine copolymers to fabricate bright and efficient blue and green single layer light emitting diodes (LEDs) These blends show enhanced quantum and power efficiency, much higher brightness and current densities and lower turn on and operating voltages compared with undoped devices. Optimised blue emission devices exhibited a maximum brightness of 1550 cd/m 2 a maximum external electroluminescence quantum efficiency of 0.9 cd/A or 0.4% and a maximum power efficiency of 0.3 lm/W. Optimised green emission devices showed a maximum brightness of 7400 cd/m 2 a maximum external electroluminescence quantum yield of 0.9% or 2.75 cd/A and a maximum power efficiency of 0.64 lm/W at high brightness.
author_names: Leonidas C Palilis

David G Lidzey

Michael Redecker

Donal D C Bradley

Michael Inbasekaran

Edmund P Woo

Weishi Wu
title: Bright and efficient blue and green light emitting diodes based on conjugated polymer blends
year: 2000