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Polycyclic heteroaromatics (PHAs) are a highly versatile class of functional materials, especially applicable as efficient luminophores in organic light‐emitting diodes (OLEDs). Those constructed by tethered phenyl surrounding the main group center attract extensive attention due to their excellent OLED device performance. However, the development of such a class of emitters is often limited to boron, nitrogen‐doped π‐conjugated heterocycles. Herein, we proposed a novel kind of blue emitter by constructing a donor‐acceptor molecular configuration, utilizing a dual sulfone‐bridged triphenylamine (BTPO) core and mono/di‐diphenylamine (DPA) substituents. The twisted D−A molecular structures and appropriate donor strength facilitate the effective separation of natural transition orbitals, endowing the emitters with charge‐transfer dominant hybridized local and charge‐transfer characteristics for the excited states. Both BTPO‐DPA and BTPO‐2DPA own small S1–T1 splitting energy, thus demonstrating blue thermally activated delayed fluorescence. The more symmetrical structure and enhanced CT features brought by additional DPA moiety confer BTPO‐2DPA with a shorter delayed fluorescence lifetime, a higher fluorescence quantum yield and narrower emission. Therefore, BTPO‐2DPA based OLED devices exhibit superior blue electroluminescence performance, with external quantum efficiencies reaching 12.31 %. [ABSTRACT FROM AUTHOR]

Stability is one of the major challenges in organic semiconductor based optoelectronic devices. A comparative study of thermally activated delayed fluorescence (TADF) based organic light emitting diodes (OLEDs) with alkali-halide lithium fluoride (LiF) vs alkaline halide magnesium fluoride (MgF2) inorganic electron injection interlayers is presented. A TADF emitter 4CzIPN doped in CBP is used as an active layer (thickness = 15 nm @6wt. % doping) in an OLED structure: Glass/ITO/PEDOT:PSS/NPD/CBP/CBP:4CzIPN/TPBi/interlayer/Al. Prior to this comparative study, a separate exercise is carried out to obtain an optimal thickness of an MgF2 interlayer on the basis of leakage current and efficiency in the TADF-OLEDs. OLEDs with an LiF interlayer showed an external quantum efficiency (EQE) of 19.7% in comparison with an MgF2 interlayer-based OLED showed slightly lower average EQE ∼19.1% at a luminance level of 100 cd/m2; these efficiency numbers are averaged over ∼60 OLEDs. These slight changes in EQE are supported by the relative photoluminescence quantum yield measurements with a whole device stack. However, alkaline halide MgF2 based TADF-OLEDs showed approximately seven-fold enhancement in the stability (LT60) under identical operating conditions. In situ photoluminescence monitoring of operational TADF-OLEDs confirmed that the probable cause of reduced lifetime is degradation of an LiF/TPBi interface. [ABSTRACT FROM AUTHOR]

Recently, organic light emitting diode (OLED) and quantum dot (QD)‐OLED displays are attracting attention as representative displays ranging from mobile to tablet, laptop, and TV markets. In these OLED and QD‐OLED displays, the individual thickness and doping ratio of functional multilayer films of organic electroluminescence (EL) are the most important factors in device characteristics such as color coordinates, efficiency, and lifetime. In particular, unlike the thickness that can be measured up to the sub‐nanometer, quantified measurement methods have not been well prepared for the various dopant contents of EL. We proposed a method to quantify the doping ratio of individual functional thin films of EL using Raman spectroscopy. First, a unique signal of each layer material of the EL was found using Raman spectroscopy, and a significant signal was classified from the resultant signal. And by utilizing the intensity of the peak of the signal, we succeeded in quantifying the doping rate using partial least squares regression and artificial intelligence. In particular, quantification was very successful even in the thinnest thin film and the thin film with the lowest dopant content. Finally, as a result of evaluation by dividing the doping rate of the EL light emitting layer in the pixel of the actually completed OLED sample by dividing it from 0 to 6%, the linear regression of the average doping rate converged to 100% was obtained. Accordingly, it succeeded in real‐time monitoring and management of the doping ratio of the EL element, which is a major factor influencing the performance and quality of OLED and QD‐OLED displays, in mass production. [ABSTRACT FROM AUTHOR]

The hot exciton mechanism has joined TTA and TADF as one of the three fundamental theories widely recognized for overcoming the spin statistics constraint in FOLEDs. Although there has been many research and application of hot exciton materials in OLED, the relationship between the molecular structure and its performance of hot exciton material is still unclear. In this work, we performed a high-throughput quantum chemistry calculation for screening hot exciton materials. Ten thousand different molecules are calculated for the electronic donor or acceptor for hot exciton material molecule. Ten hot exciton material molecules were designed based on predicted properties, while other molecular properties were also analyzed. This research represents a significant opportunity to enhance our comprehension of the interplay between material structure and performance and could potentially accelerate the design of hot exciton materials. [ABSTRACT FROM AUTHOR]

Semiconductor junctions are among the most important material interfaces in modern technology. The solid polymer light‐emitting electrochemical cell (PLEC) possesses a semiconducting polymer homojunction that is reminiscent of a conventional p–n junction but also exhibits distinct features that are profoundly intriguing. The PLEC junction is formed under bias when the propagating p‐ and n‐doping fronts make contact. The PLEC junction can be immobilized by cooling after the initial junction formation. Further, the resulting frozen junction can be relaxed, or partially de‐doped into a p–i–n junction by controlled heating/cooling cycles. It is on such a frozen polymer p–i–n junction that the authors observed one of the most puzzling phenomena in organic electroluminescence (EL). The frozen p–i–n junction displays the brightest reverse bias (RB) EL ever imaged in a polymer junction and a large photovoltage. Moreover, the RB EL exhibits hypersensitivity to temperature, increasing in intensity by 22.6% K−1 when the de‐doped cell is cooled from 250 to 200 K. A model based on the tunnel injection of charge carriers with fast transit time across the intrinsic region explains the RB EL's hypersensitivity to temperature and super‐linear dependence on cell current. [ABSTRACT FROM AUTHOR]

Organic electroluminescence is considered as the most competitive alternative for the future solid‐state displays and lighting techniques owing to many advantages such as self‐luminescence, 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 high‐performance 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. [ABSTRACT FROM AUTHOR]

We synthesized a polymer, poly(N,N′-diphenyl-N,N′-bis(4-methylphenyl)-1,4-phenylenediam ine1,3-diisopropenylbenzene) (PDAIPB), of which the energy of the highest occupied molecular orbital was measured to be 5.6 eV below vacuum level. In this article, PDAIPB was used as a hole transporter in a light emitting diode, with tri(8-hydroxyquinoline)-aluminum (Alq[sub 3]) as an electron transporter and emitting layer to ameliorate the stability of the device, and fullerene doped in the hole transporting layer as a sensitizer to study the influence of sensitizer on organic electroluminescence (EL). Internal EL quantum efficiency as high as 7.8% was obtained under an applied electric field of 1.2x10[sup 6] V/cm and doping fullerene concentration of 0.9 wt %. A function for EL quantum efficiency in terms of the dopant concentration is derived. The theoretical analysis is consistent with the experimental results. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Investigates the degradation process of a metal top electrode before and/or after applying voltage by atomic force microscopy, scanning electron microscopy, Auger electron spectroscopy and fluorescence microscopy. Description of the degradation process; Applications for organic electroluminescence (EL) devices; Significance of the observation of the morphological change of the metal surfaces; Relationship between the current density and the EL intensity.

Two warm white organic light-emitting diodes (WOLEDs) based on novel/efficient phosphor-only emitting systems exhibit very high peak electroluminescence (EL) efficiencies of 25.0/22.5% and 71.3/59.3 lm W−1 and desirable color rendering index (CRI) values of 81/90. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) organic optoelectronic devices have attracted extensive research owing to their great potential in variety of applications such as biological and chemical sensing, excitation light sources, high-density information storage, and optoelectronic circuits. This review focusses on UV organic light-emitting diodes and organic solid-state lasers, and covers their recent development from organic chromophores and device configuration to practical applications. Firstly, materials with efficient short-wavelength emission are summarized with an emphasis on the characteristics of their structures. Subsequently, we outline the device architectures used for increasing the efficiency and performance of the devices. Finally, we discuss the progress and challenges of using UV OLEDs and organic solid-state lasers as excitation sources in emerging applications and hope this can help stimulate the exploitation of UV light sources in more applications in future. [ABSTRACT FROM AUTHOR]

A spin-flip from a triplet to a singlet excited state, that is, reverse intersystem crossing (RISC), is an attractive route for improving light emission in organic light-emitting diodes, as shown by devices using thermally activated delayed fluorescence (TADF). However, device stability and efficiency roll-off remain challenging issues that originate from a slow RISC rate (kRISC). Here, we report a TADF molecule with multiple donor units that form charge-resonance-type hybrid triplet states leading to a small singlet–triplet energy splitting, large spin–orbit couplings, and a dense manifold of triplet states energetically close to the singlets. The kRISC in our TADF molecule is as fast as 1.5 × 107 s−1, a value some two orders of magnitude higher than typical TADF emitters. Organic light-emitting diodes based on this molecule exhibit good stability (estimated T90 about 600 h for 1,000 cd m−2), high maximum external quantum efficiency (>29.3%) and low efficiency roll-off (<2.3% at 1,000 cd m−2). An organic molecule, 5Cz-TRZ, with multiple donor units supports fast reverse intersystem crossing, allowing fabrication of high-performance organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

An efficient white organic light-emitting diode employing a simple/ advanced phosphor-only emitting system based on a novel bipolar sky blue phosphorescent host realizes high-quality warm-white electroluminescence emission with very high efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Actualizing highly efficient solution‐processed thermally activated delayed fluorescent (TADF) organic light‐emitting diodes (OLEDs) at high brightness becomes significant to the popularization of purely organic electroluminescence. Herein, a highly soluble emitter benzene‐1,3,5‐triyltris((4‐(9,9‐dimethylacridin‐10(9H)‐yl)phenyl)methanone was developed, yielding high delayed fluorescence rate (kTADF > 105 s−1) ascribed to the multitransition channels and tiny singlet–triplet splitting energy (ΔEST ≈ 32.7 meV). The triplet locally excited state is 0.38 eV above the lowest triplet charge‐transfer state, assuring a solely thermal equilibrium route for reverse intersystem crossing. Condensed state solvation effect unveils a hidden “trade‐off”: the reverse upconversion and triplet concentration quenching processes can be promoted but with a reduced radiative rate from the increased dopant concentration and the more polarized surroundings. Striking a delicate balance, corresponding vacuum‐evaporated and solution‐processed TADF‐OLEDs realized maximum external quantum efficiencies (EQEs) of ≈26% and ≈22% with extremely suppressed efficiency roll‐off. Notably, the wet‐processed one achieves to date the highest EQEs of 20.7%, 18.5%, 17.1%, and 13.6%, among its counterparts at the luminance of 1000, 3000, 5000, and 10 000 cd m−2, respectively. [ABSTRACT FROM AUTHOR]

In this paper, organic electroluminescence fluoropolymer film devices, i.e., organic light-emitting diodes (OLEDs) comprising polychlorotrifluoroethylene (PCTFE) films treated by an atmospheric-pressure nonthermal plasma (NTP) graft-polymerization process, are investigated. PCTFE films can provide a long lifetime for OLEDs because of their excellent gas barrier properties; however, they are difficult to laminate, owing to low adhesiveness. The surfaces of PCTFE films are treated by an atmospheric-pressure NTP-graft-polymerization process to improve their adhesiveness, and then, indium tin oxide and a luminous layer are deposited on the treated PCTFE films. As a result, OLEDs comprising PCTFE films are successfully demonstrated. [ABSTRACT FROM AUTHOR]

Presents information on a study which ascribed the electron injection currents flowing from magnesium and aluminum into tris(8-hydroxyquinolino)aluminum to the thermionic emission mechanism of electroluminescence devices. Methodology of the study; Results and discussion; Conclusions.

We report the generation and detection of bipolar organic electroluminescence of porphyrin molecules from a nanoscale junction in an ultrahigh vacuum scanning tunneling microscope (STM). Clear molecular fluorescence from porphyrin molecules near metal substrates has been realized through highly localized electrical excitation of molecules in proximity to a sharp tip apex. The molecular origin of the luminescence, arising from the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) radiative transitions of neutral molecules, is clearly established by the observed well-defined vibrationally resolved fluorescence spectra that match perfectly with conventional photoluminescence data from molecular thin films. The molecules fluoresce at low onset voltages for both bias polarities, presenting an example of bipolar organic electroluminescence at the nanoscale. Such bipolar operation suggests a double-barrier model for electron transport, with hot electron injection into unoccupied states of molecules in both polarities. The optical behavior of molecules in the tunnel junction is also found sensitive to the electronic properties of molecules and energy level alignment at the interface. These results offer new information to the optoelectronic behavior of molecules in a nanoscopic environment and may open up new routes to the development of single-molecule science and molecular scale electronics. [ABSTRACT FROM AUTHOR]

Introduction Organic electroluminescence displays ( OELD) use organic materials that self-emit light with the passage of an electric current. OELD provide high contrast, excellent color reproducibility at low brightness, excellent video images, and less restricted viewing angles. OELD are thus promising for medical use. This study compared the utility of an OELD with conventional liquid crystal displays ( LCD) for imaging in orthopedic endoscopic surgery. Methods One OELD and two conventional LCD that were indistinguishable in external appearance were used in this study. Images from 18 patients were displayed simultaneously on three monitors and evaluated by six orthopedic surgeons with extensive surgical experience. Images were shown for 2 min, repeated twice, and viewed from the front and side (diagonally). Surgeon rated both clinical utility (12 parameters) and image quality (11 parameters) for each image on a 5-point scale: 1, very good; 2, good; 3, average; 4, poor; and 5, very poor. Results For clinical utility in 16 percutaneous endoscopic discectomy cases, mean scores for all 12 parameters were significantly better on the OELD than on the LCD, including organ distinguishability (2.1 vs 3.2, respectively), lesion identification (2.2 vs 3.1), and overall viewing impression (2.1 vs 3.1). For image quality, all 11 parameters were better on the OELD than on LCD. Significant differences were identified in six parameters, including contrast (1.8 vs 2.9), color reproducibility in dark areas (1.8 vs 2.9), and viewing angle (2.2 vs 2.9). Conclusion The high contrast and excellent color reproducibility of the OELD reduced the constraints of imaging under endoscopy, in which securing a field of view may be difficult. Distinguishability of organs was good, including ligaments, dura mater, nerves, and adipose tissue, contributing to good stereoscopic images of the surgical field. These findings suggest the utility of OELD for excellent display of surgical images and for enabling safe and highly accurate endoscopic surgery. [ABSTRACT FROM AUTHOR]

An Alq 3 (tris-(8-hydroxyquinolinato)aluminium(III)) organic electroluminescence (EL) device has been studied from the point of view of spin chemistry. The external magnetic field effect (MFE) on the EL reveals the positive effect suggesting that the quenching of the charged spin pair from the triplet state is faster than that of the singlet state. The data also suggest that the diffusive motion of charges in this solid phase is similar to that in liquid, and the existence of semi-discrete level-crossing regions is proposed. Furthermore, the MFE on the photo-induced current from this device as an organic photovoltaic cell is also shown. [ABSTRACT FROM AUTHOR]

Utilizing a series of bay‐annulated perylene ester imides (PEIs) doped in polyvinylcarbzole (PVK) as emissive layer, host‐guest organic light emitting diodes were fabricated and the electroluminescence behaviors of these devices have been explored. The devices exhibited emission from both PVK as well as PEI mainly due to the partial Förster resonance energy transfer from PVK to the emissive dopant. In order to achieve better device performance, two different electron transport layers, BPhen and TPBi were used. A remarkable improvement in the emission brightness and lower turn on voltage was observed, when TPBi was used as an electron‐transporting layer instead of BPhen. Incorporation of TPBi resulted in a lower electron injection barrier of TPBi‐PVK interface, which facilitates more electron injection into the emissive layer thus resulting in an increased recombination at a comparatively lower voltage. Also, the intensity of blue emission from PVK was enhanced in the case of TPBi based devices, resulting in an overall white electroluminescence, which is of high technological importance. [ABSTRACT FROM AUTHOR]

We reported high-performance organic light-emitting diodes (OLEDs) with a maximum efficiency of 42.3 lm W−1 and color rendering index of 92 by facilitating charge carrier transportation and controlling the recombination zone. In addition, we demonstrated that inserting a thin interlayer in emitting layer prevented energy transfer between blue and green emission layers, providing a relative chromatic-stability OLEDs. Furthermore, the device also exhibit a rather low correlated color temperature (2202 K), corresponding to an excellent warm WOLED, which could meet the special requirement of energy saving and environment protection. [ABSTRACT FROM AUTHOR]

In organic light emitting devices (LEDs) various types of emissive states are created: (i) molecular excited states (localized excitons), or bimolecular (B-M) species: excimers, electromers, exciplexes and electroplexes. The consequences of the formation of B-M excited species for optical and electrical characteristics of organic LEDs are discussed and illustrated by various examples. While molecular excitons can be viewed in some sense as correlated electron--hole (e-h) pairs with the inter-charge mean separation less than an intermolecular spacing, the size of B-M excited states amounts usually to one or two intermolecular spacings. The B-M species can be classified as electrically balanced states, formed under energy and charge exchange between neighbour molecules, and have either a singlet or a triplet character. The focus of the paper is on excimer and exciplex forming single phosphorescent dopant blends-based emitting layers but characteristic features of other B-M excited species (electromers and electroplexes) and their emissions are also mentioned. Of particular interest in modern optoelectronics are white and infrared organic LEDs. It is shown how excimer and exciplex emissions can be employed in manufacturing such devices. Examples include efficient white and near-infrared LEDs, based on single dopant emitters of an efficient N-C-N-coordinated platinum(II) complex phosphor, and their improved versions, obtained by modification of the emitter matrix materials and electron injecting electrodes. [ABSTRACT FROM AUTHOR]

A molecularly-ordered thin film of vacuum deposited 1-TNATA(4,4',4''-tris(N-(1-naphthyl)-N-phenylamino) triphenylamine) as a hole injection layer (HIL) is placed between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in multi-layered organic electroluminescence (EL) diodes. The molecular ordering of 1-TNATA thin film was obtained by thermal annealing and electromagnetic field after vacuum deposition and the film was investigated by the Raman spectra, XRD, and AFM. It was found that the current density-voltage (J-V) and luminance-voltage (L-V) characteristics of the multi-layered diodes were improved due to the ordering of 1-TNATA molecules, which could enhance the charge carrier mobility and luminance efficiency among the organic molecules in the molecularly-ordered film. [ABSTRACT FROM AUTHOR]

Conducting polymer polydimethylsiloxane (PDMS) is studied for the high performance electrode of organic electroluminescence devices. A method to prepare the electrode consisting of a SiC thin film and PDMS is investigated. By using ultra thin SiC films with different thicknesses, the organic electroluminescence devices are obtained in an ultra vacuum system with the model device PDMS/SiC/PPV/Alq3, where PPV is poly para-phenylene vinylene and Alq3 is tris(8-hydroxyquinoline) aluminium. The capacitance-voltage (C - V), capacitance-frequency (C - F), current-voltage (I - V), radiation intensity-voltage (R - V) and luminance efficiency-voltage (E - V) measurements are systematically studied to investigate the conductivity, Fermi alignment and devices properties in organic semiconductors. Scanning Kelvin probe measurement shows that the work function ofPDMS/SiC anode with a 2.5-nm SiC over layer can be increased by as much as 0.28 eV, compared to the conventional ITO anode. The result is attributed to the charge transfer effect and ohmic contacts at the interface. [ABSTRACT FROM AUTHOR]

The vacuum deposited amorphous organic thin film melamine cyanurate (MC) is found to possess an electrical switching property. The as-fabricated fresh thin film is at a semiconductor state and shows a rectification property in a range of several voltages. Under a higher applied voltage, the resistance of the film changes to a lower value, and shows linearity in its current-voltage relationship. After the application of a negative driving voltage for no more than 100 s, the MC film returns from the resistor state to the semiconductor state with a higher impedance. Based on this reproducible switching phenomenon, a type of voltage-controlled switchable organic electroluminescence device was fabricated by inserting the MC layer between the anode indium tin oxide (ITO) and the hole transport layer N,N'-bis (3-methylphenyl)-N,N'-diphenyl-benzidine (TPD). In the forward driving voltage scan (for example, increasing the driving voltage from 0 to 16 V), the impedance is higher and the current density is lower; then the scan is backward (decreasing the driving voltage from 16 to 0 V), the impedance becomes lower and the current density becomes higher. Corresponding to the two different current density states at the same driving voltage, the device luminance also reaches two different states, one is lower and another is higher. This transition from a high (ON) to low luminance (OFF) renders a prototype to realize a switchable organic electroluminescence. [ABSTRACT FROM AUTHOR]

Purpose. To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit patternreversal visual evoked potentials (p-VEPs). Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 x 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0msec on the cathode-ray tube (CRT) screen and 0.5msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account. [ABSTRACT FROM AUTHOR]

In organic electroluminescence there is a sharp contradiction between the applicability of band model and molecular theory. This contradiction arose from the very beginning of extended study. In this report we studied the blue spectral shift in the newly discovered solid state cathodoluminescence when the applied voltage is increased. There are three different kinds of spectra in three intervals of applied voltage. The reason of this spectral shift is found to be the field ionization of exciton. The switching on of recombination starts only after the beginning of this field ionization. The exciton emission obeys molecular theory and the recombination obeys band model. Thus the demarcation is the appearance of field ionization of excitons. Since the ionization changes with electric field continuously, there is a region of coexistence of these two processes. [ABSTRACT FROM AUTHOR]

We demonstrate a method for achieving polarized organic electroluminescence for liquid crystalline conjugated polymers that allows the polymer to be deposited directly onto the anode. The technique utilizes a top-down alignment approach whereby the predeposited polymer was aligned from above using a rubbed polyimide master and a smectic liquid crystal transfer layer. The liquid crystal/polyimide master bilayer was sandwiched with the liquid crystalline polymer that had been deposited onto the electrode. The sandwiched layers were then heated to achieve alignment before the removal of the polyimide master and liquid crystal transfer layer. Using this method, poly[2,7-{9,9-di(2-ethylhexyl)}fluorene] (PF2-6) was aligned to give an anisotropic polymer film. Light emitted from single layer light-emitting diodes containing the aligned PF2-6 had integrated dichroic ratios of up to 9.7. At 100 cd/m[sup 2], the single layer devices had external quantum and power efficiencies of 0.08% and 0.05 lm/W, respectively. Bilayer devices containing an electron transport layer between the PF2-6 and the cathode gave emitted light with good dichroic ratios and with the external quantum and power efficiencies at 100 cd/m[sup 2] being increased to 2.2% and 1.1 lm/W. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A class of anthracene derivative which is suitable used as emitting materials for producing efficient and stable blue emission for full color organic electroluminescence (EL) devices has been developed. Multilayer organic EL devices using these fluorescent materials as an emitting layer produced blue emissions with good chromaticity and luminous efficiency as high as 3.5 cd/A. The half life of 4000 h of blue emission EL device with initial light output 700 cd/m2 has been achieved. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the synthesis of a red light‐emitting and photopolymerizable smectic liquid crystal (reactive mesogen). We investigate the suitability of polymer networks formed from smectic reactive mesogens for use in organic light‐emitting diodes (OLEDs). The use of mixtures of smectic reactive mesogens is shown to lower the processing temperature for the fabrication of OLEDs to room temperature. We also report efficient energy transfer from a nematic polymer network host to a smectic light‐emitting dopant and polarized emission from a polymer network formed from an aligned smectic reactive mesogen. [ABSTRACT FROM AUTHOR]

Focuses on the construction of red organic electroluminescence (EL) devices with a reduced porphyrin compound, tetraphenylchlorin. EL properties of the devices; Variation in the emission color of the devices upon exposure to different concentrations; Characteristics of the compound that affected the devices' behavior.

In this paper, we report the optical and electrical characteristics of organic electroluminescent diodes (OELDs) using phenylamine derivatives. The novel hetero-cyclic bis-styryl dyes, 2,2′-(1,4-phenylenedivinylene)bis-3,3′-dimethylindoline (PDV-DMI) and 2,2′-(1,4-phenylenedivinylene)bis-8-acetoxyquinoline (PDV-AQ) were synthesized according to phase-transfer catalysis (PTC). The structure of fabricated OELDs was ITO anode/PEDOT/TPD/PDV-DMI or PDV-AQ/Al cathode. The brightness of the EL diodes with PDV-DMI or PDV-AQ had a maximum peak about 3700 nW/cm 2 at 156 mA/cm 2 and 6000 nW/cm 2 at 130 mA/cm 2 , respectively. The maximum EL peaks from PDV-DMI and PDV-AQ are at 615 nm and 592 nm which are corresponding to red and orange emission, respectively. The CIE coordinates of PDV-DMI and PDV-AQ are x=0.5635, y=0.4277 and x=0.4725, y=0.4640, respectively. [ABSTRACT FROM AUTHOR]

A significant increase in electroluminescence was achieved through coupling with localized surface plasmons in a single layer of Au nanoparticles. We fabricated a thin-film organic electroluminescence diode, which consists of an indium tin oxide (ITO) anode, a Au nanoparticle array, a Cu phthalocyanine hole transport layer, a tris(8-hydroxylquinolianato) aluminum (III) electron transport layer, a LiF electron injection layer, and an Al cathode. The device structure, with size-controlled Au particles embedded on ITO, can be used to realize the optimum distance for exciton-plasmon interactions by simply adjusting the thickness of the hole transport layer. We observed a 20-fold increase in the molecular fluorescence compared with that of a conventional diode structure. [ABSTRACT FROM AUTHOR]