Showing papers on "OLED published in 2006"

Organic light emitting display (OLED) and its method of fabrication

Abstract: An Organic Light Emitting Display (OLED) and a method of fabricating the OLED includes: a substrate including a pixel region and a non-pixel region; a gate electrode arranged in the non-pixel region of the substrate; a first insulating layer arranged on the substrate having the gate electrode formed thereon, and having an open groove on an upper surface of a region opposite to the gate electrode; a semiconductor layer buried in the groove and including a source region, a channel region and a drain region; and an organic thin film layer arranged in the pixel region of the substrate. A common electrode is arranged between the drain region of the semiconductor layer and the organic thin film layer to electrically couple the drain region to the organic thin film layer.

Organic light-emitting diode (OLED) technology: materials, devices and display technologies

Abstract: Since the breakthrough by Kodak in 1987, organic light-emitting diodes (OLEDs) have been seen as one of the most promising technologies for future displays. A number of materials have been developed and improved in order to fulfil the requirements of this application. The materials differ from one another by their structure but also by the mechanism involved in the electroluminescence produced (fluorescence versus phosphorescence). When properly stacked, these materials result in a device that can achieve the required high efficiency and long lifetime. Such red, green and blue devices can then be combined in matrices to become the core of a display. Building up these structures onto a display backplane is one of the challenges facing the industry. The circuitry for driving the pixels can be adapted to the OLED, sometimes at the expense of the simplicity of the display, but bearing in mind that the fabrication process must remain industrially viable.  2006 Society of Chemical Industry

All-organic active matrix flexible display

Abstract: We have fabricated pentacene organic thin-film transistor (OTFT) driven active matrix organic light-emitting diode (OLED) displays on flexible polyethylene terephthalete substrates These displays have 48×48 bottom-emission OLED pixels with two pentacene OTFTs used per pixel Parylene is used to isolate the OTFTs and OLEDs with good OTFT yield and uniformity

Organic Light-Emitting Diodes Having Carbon Nanotube Anodes

Abstract: Single-walled carbon nanotube (SWNT) films on flexible PET (polyethyleneterephthalate) substrates are used as transparent, flexible anodes for organic light-emitting diodes (OLEDs). For polymer-based OLEDs having the structure: SWNT/PEDOT-PSS:MeOH/TFB (poly(9,9dioctylfluorene-co-N-(4-butylphenyl)diphenylamine)) + TPD-Si2 (4,4′-bis[(p-trichlorosilylpropylphenyl)phenylamino]biphenyl) /BT (poly(9,9dioctylfluorene-co-benzothiadiazole))/CsF/Al, a maximum light output of 3500 cd/m 2 and a current efficiency of 1.6 cd/A have been achieved. The device operational lifetime is comparable to that of devices with Sn-doped In 2O3 (ITO)/PET anodes. The advantages of this novel type of anode over conventional ITO are discussed.

Enhanced emission efficiency in organic light-emitting diodes using deoxyribonucleic acid complex as an electron blocking layer

Abstract: Enhanced electroluminescent efficiency using a deoxyribonucleic acid (DNA) complex as an electron blocking (EB) material has been demonstrated in both green- and blue-emitting organic light-emitting diodes (OLEDs). The resulting so-called BioLEDs showed a maximum luminous efficiency of 8.2 and 0.8cd∕A, respectively. The DNA-based BioLEDs were as much as 10× more efficient and 30× brighter than their OLED counterparts.

Towards See-Through Displays: Fully Transparent Thin-Film Transistors Driving Transparent Organic Light-Emitting Diodes**

Abstract: Fully transparent computer displays have, until now, been the vision of science-fiction movies. Nevertheless, there are numerous applications for these devices ranging, for example, from head-mounted displays to their integration in automotive windshields. In this paper we demonstrate that this vision is on the verge of becoming reality. The realization of entirely transparent displays requires both transparent light-emitting devices, in our case organic light-emitting diodes (OLEDs) with transparent contacts, and a driving scheme based on transparent thin-film transistors (TTFTs). Since the early reports on electroluminescence from multilayer, thin-film devices composed of vacuum-sublimed small organic molecules [1] and spin-coated conjugated polymers, [2] substantial research has been devoted to the improvement of device efficiencies, color purity, and lifetime. Incitement of this development is the potential use of OLEDs in future commercial flat-panel displays. OLEDs usually consist of a layer sequence of organic functional materials (charge transporters/blockers/emitters) with an overall thickness of the order of 100 nm. Most of these materials absorb light in the deep-blue or ultraviolet spectral region and are nearly transparent in the visible part of the spectrum. Organic layers applied to emit visible light are often based on so-called guest–host systems, in which a wide-bandgap host material (absorbing in the UVonly) is doped with a few weight percent of a light-emitting dye. [3] As a result, the emitting layer appears transparent. Transparent conductive oxides, most prominently indium tin oxide (ITO) and aluminum-doped ZnO (AZO), may be used as electrical contacts to OLEDs. Therefore, OLEDs seem to be promising devices for the realization of entirely transparent visible-light emitters. [4–6] OLED displays driven in passive-matrix mode are based on conventional bottom-emitting OLEDs and are considered as an approach to fabricate small-sized, low-information-content displays with moderate pixel counts. To accomplish largerarea, high-resolution OLED displays an active-matrix-addressing scheme has been suggested. [7] Conventional a-Si:H or poly-Si TFT backplanes are not suitable as drivers for transparent displays because they are opaque in the visible part of the spectrum. Putting pixels and transistors next to each other would compromise the displays’ fill factor. Organic field-effect transistors (OFETs) as pixel drivers for OLEDs have been discussed by Sirringhaus et al. [8] Transparent OFETs have also been reported. [9] However, their performance is still poor; transparent active pixels using OFETs have not yet been demonstrated. Therefore, in this paper we focus on the production of TTFTs based on the wide-bandgap oxide semiconductor zinc tin oxide (ZnO)x(SnO2)1–x ,a s a viable alternative to previously fabricated devices. Recently, research on TTFTs with channels made from ox

Highly Efficient Green‐Emitting Phosphorescent Iridium Dendrimers Based on Carbazole Dendrons

Abstract: Green-emitting iridium dendrimers with rigid hole-transporting carbazole dendrons are designed, synthesized, and investigated. With second-generation dendrons, the photoluminescence quantum yield of the dendrimers is up to 87% in solution and 45% in a film. High-quality films of the dendrimers are fabricated by spin-coating, producing highly efficient. non-doped electrophosphorescent organic light-ernitting diodes (OLEDs). With a device structure of indium tin oxide/poly(3,4-ethylenedioxythiopheiie):poly(styrene sulfonic acid)/neat dendrimer/1,3,5-tris(2-N-phenylbenzimidazolyl)benzene/LiF/Al, a maximum external quantum efficiency (EQE) of 10.3% and a maximum luminous efficiency of 34.7 cd A(-1) are realized. By doping the dendrimers into a carbazole-based host, the maximum EQE can be further increased to 16.6%. The integration of rigid hole-transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution-processable dendrimers for OLED applications.

Organic Light Emitting Devices: Synthesis, Properties and Applications

Abstract: 1 Inorganic Semiconductors for Light-emitting Diodes (E. Fred Schubert, Thomas Gessmann, and Jong Kyu Kim). 1.1 Introduction. 1.2 Optical Emission Spectra. 1.3 Resonant-cavity-enhanced Structures. 1.4 Current Transport in LED Structures. 1.5 Extraction Efficiency. 1.6 Omnidirectional Reflectors. 1.7 Packaging. 1.8 Conclusion. References. 2 Electronic Processes at Semiconductor Polymer Heterojunctions (Arne C. Morteani, Richard H. Friend, and Carlos Silva). 2.1 Introduction. 2.2 Charge Capture at Polymer Heterojunctions. 2.3 Exciton Dissociation at Polymer Heterojunctions. 2.4 Morphology-dependent Exciton Retrapping at Polymer Heterojunctions. 2.5 Summary. Acknowledgments. References. 3 Photophysics of Luminescent Conjugated Polymers (Dirk Hertel and Heinz Bssler). 3.1 Introduction. 3.2 Spectroscopy of Singlet States. 3.3 Optically Induced Charge Carrier Generation. 3.4 Triplet States. 3.5 Resum. Acknowledgement. References. 4 Polymer-Based Light-Emitting Diodes (PLEDs) and Displays Fabricated from Arrays of PLEDs (Xiong Gong, Daniel Moses and Alan J. Heeger). 4.1 Introduction. 4.2 LEDs Fabricated from Semiconducting Polymers. 4.3 Accurate Measurement of OLED/PLED Device Parameters. 4.4 Fowler-Nordheim Tunneling in Semiconducting Polymer MIM Diodes. 4.5 Pixilated Displays. 4.6 Thickness Dependence of Electroluminescence Efficiency. 4.7 Limits on the Electroluminescence Efficiency. 4.8 White-light emission. 4.9 Conclusion. Note. Acknowledgement. References. 5 Metal/Polymer Interface Studies for Organic Light-Emitting Devices (Man-Keung Fung, Chun-Sing Lee, and Shuit-Tong Lee). 5.1 Review of Organic Light-Emitting Diodes and their Fundamental Interface Studies. 5.2 Polymer Materials, their Preparations, and Experimental Details. 5.3 Chemistry and Electronic Properties of Metal/F8BT. 5.4 Role of Ytterbium and Ytterbium/Cesium Fluoride on the Chemistry of F8BT. 5.5 Highly Efficient and Substrate-Independent Ytterbium/Cesium Fluoride Cathodes. 5.6 Conclusions. Acknowledgements. References. 6 The Synthesis of Electroluminescent Polymers (Andrew C. Grimsdale). 6.1 Introduction. 6.2 Poly(arylene vinylene)s. 6.3 Poly(arylene ethynylene)s. 6.4 Polyarylenes. 6.5 EL Polymers with Isolated Chromophores. 6.6 Stability of EL Polymers. 6.7 Conclusion. References. 7 Charge-transporting and Charge-blocking Amorphous Molecular Materials for Organic Light-emitting Diodes (Yasuhiko Shirota). 7.1 Introduction. 7.2 Amorphous Molecular Materials. 7.3 Requirements for Materials in OLEDs. 7.4 Amorphous Molecular Materials for Use in OLEDs. 7.5 Charge Transport in Amorphous Molecular Materials. 7.6 Outlook. References. 8 Dendrimer Light-Emitting Diodes (John M. Lupton). 8.1 Introduction. 8.2 The Dendrimer Concept. 8.3 Electroluminescent Dendritic Materials. 8.4 Electronic Properties. 8.5 Dendrimer Devices. 8.6 Dendronized Polymers. 8.7 Conclusions. References. 9 Crosslinkable Organic Semiconductors for Use in Organic Light-Emitting Diodes (OLEDs) (Klaus Meerholz, Christoph-David Mller, Oskar Nuyken). 9.1 Introduction. 9.2 Multiple-Layer Deposition. 9.3 Patterning. 9.4 Conclusion and Outlook. Acknowledgements. References. 10 Hybrid OLEDs with Semiconductor Nanocrystals (Andrey L. Rogach and John M. Lupton). 10.1 Introduction. 10.2 LEDs in the Visible based on Composites of Semiconductor Nanocrystals and Polymers or Nanocrystals and Small Organic Molecules. 10.3 Near-infrared LEDs based on Composites of Semiconductor Nanocrystals and Polymers or Small Organic Molecules. 10.4 Concluding Remarks. References. 11 Polymer Electrophosphorescence Devices (Xiaohui Yang and Dieter Neher). 11.1 Introduction. 11.2 Phosphorescent Dyes. 11.3 Transfer Processes in Polymer Hosts Doped with Phosphorescent Dyes. 11.4 Polymer Phosphorescence Devices based on PVK. 11.5 Phosphorescent Devices with Other Host Polymers. 11.6 Fully Functionalized Polymers. 11.7 Conclusion and Outlook. Acknowledgement. References. 12 Low-threshold Organic Semiconductor Lasers (Daniel Schneider, Uli Lemmer, Wolfgang Kowalsky, Thomas Riedl). 12.1 Introduction. 12.2 Fundamentals of Organic Semiconductor Lasers. 12.3 Low-threshold Organic Lasing. 12.4 Comparison of Organic Laser Properties. 12.5 Electrically Driven Organic Lasers. 12.6 Summary and Outlook. References. Subject Index.

High‐Efficiency White‐Light‐Emitting Devices from a Single Polymer by Mixing Singlet and Triplet Emission

Abstract: It is therefore desirable to obtain white-light emission from a single-component material so as to avoid these drawbacks. In the past few years, studies in this field have attracted growing interest and encouraging progress has been made. Li et al. [9] fabricated a single-component white organic light-emitting diode (OLED) by using 1,3,5-tris(2-(9-ethylcarbazyl3)ethylene)benzene (TECEB) as the emitting species. The green- and red-light emission of the electroluminescence (EL) device from TECEB is produced by electric excitation. The EL device showed a luminance efficiency of 1.1 cdA –1 with Commission Internationale de L’Eclairage (CIE) coordinates of (0.29, 0.31). Lee et al. [10] fabricated a single-component WPLED using an oxadiazole-containing, phenylene-vinylene ether-linkage copolymer, POPPPV3, as emitting species. The PLED made from annealed POPPPV3 had a luminance efficiency of 0.071 cdA –1 , and a maximum luminance of 60 cdm –2 with CIE coordinates of (0.30, 0.37). Furuta et al. [11]

Green fluorescent organic light-emitting device with external quantum efficiency of nearly 10%

Abstract: Green fluorescent organic light-emitting device (OLED) exhibiting a high external quantum efficiency of nearly 10% has been developed. The OLED consists of simple three organic layers, using NPB, 0.8% C545T doped TPBA, and DBzA as a hole-transporting layer, an emitting layer, and an electron-transporting layer, respectively, [fluorocarbon coated indium tin oxide/NPB (60 nm)/08% C545T doped TPBA (40 nm)/DBzA (20 nm)/LiF (1 nm/Al], where NPB is 4,4′-bis (N-phenyl-1-naphthylamino)biphenyl, C545T is 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]pyrano[6 7 8-ij]quinolizin-11-one, TPBA is 9,9′,10,10′-tetraphenyl-2,2′-bianthracene, and DBzA is 9,10-bis[4-(6-methylbenzothiazol-2-yl)phenyl]anthracene. The high external quantum efficiency is maintained in the wide range of current density of 2–100 mA∕cm2. The current efficiency and power efficiency of the OLED are also very high, 29.8 cd/A and 26.2 lm/W, respectively, at a current density of 20 mA/cm2. The OLED is promising for prac...

Organic light emitting devices with enhanced outcoupling via microlenses fabricated by imprint lithography

Abstract: High efficiency white organic light emitting devices (WOLEDs) with optical outcoupling enhanced by hexagonal polymethylmethacrylate microlens arrays fabricated by imprint lithography on a glass substrate are demonstrated. Monte Carlo and finite difference time domain simulations of the emitted light are used to optimize the microlens design. The measured enhancement of light outcoupling and the angular dependence of the extracted light intensity are in agreement with the simulation. Using microlens arrays, we demonstrate a fluorescent/phosphorescent WOLED with a maximum external quantum efficiency of (14.3±0.3)% at 900cd∕m2 and power efficiency of 21.6±0.5lm∕W at 220cd∕m2. The electroluminescent spectra at viewing angles from normal to the substrate plane, to 60° off normal, remain almost unchanged, giving a color rendering index of 87.

Carbon nanotube sheets as electrodes in organic light-emitting diodes.

Abstract: High performance organic light-emitting diodes (OLEDs) were implemented on transparent and conductive single-wall carbon nanotube sheets. At the maximum achieved brightness of 2800cdm−2 the luminance efficiency of our carbon nanotube-based OLED is 1.4cdA−1 which is comparable to the 1.9cdA−1 measured for an optimized indium tin oxide anode device made under the same experimental conditions. A thin parylene buffer layer between the carbon nanotube anode and the hole transport layer is required in order to readily achieve the measured performance.

Toward Functional π-Conjugated Organophosphorus Materials: Design of Phosphole-Based Oligomers for Electroluminescent Devices

Abstract: The photophysical, electrochemical, and optoelectronic properties of conjugated systems incorporating dibenzophosphole or phosphole moieties are described. Dibenzophosphole derivatives are not suitable materials for OLEDs due to their weak photoluminescence (PL) in the solid state and the instability of the devices. Variation of the substitution pattern of phospholes and chemical modification of their P atoms afford thermally stable derivatives, which are photo- and electroluminescent. Comparison of the optical properties of solution and thin film of thioxophospholes shows that these compounds do not form aggregates in the solid state. This property, which is also supported by an X-ray diffraction study of three novel derivatives, results in an enhancement of the fluorescence quantum yields in the solid state. In contrast, (phosphole)gold(I) complexes exhibit a broad emission in thin film, which is due to the formation of aggregates. Single- and multilayer OLEDs using these P derivatives as the emissive layer have been fabricated. The emission color of these devices and their performances vary with the nature of the P material. Interestingly, di(2-thienyl)thiooxophosphole is an efficient host for the red dopant DCJTB, and devices using the gold complexes have broad emission spectra.

Highly efficient white organic light emitting diodes comprising an interlayer to separate fluorescent and phosphorescent regions

Abstract: White organic light emitting diodes combining the phosphorescent green and orange-red emitting systems fac tris(2-phenylpyridine) iridium doped 4,4′,4″-tris(N-carbazolyl)-triphenylamine (TCTA) and iridium(III)bis(2-methyldibenzo-[f,h]quinoxaline)(acetylacetonate) doped N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine with the blue fluorescent dye 2,2′,7,7′-tetrakis(2,2-diphenylvinyl)spiro-9,9′-bifluorene (Spiro-DPVBi) are presented. By introducing a thin layer of coevaporated TCTA and 2,2′,2″ (1,3,5-benzenetriyl) tris-[1-phenyl-1H-benzimidazole] between the phosphorescent and the fluorescent region, both singlet and triplet excitons are confined efficiently, whereas charge carriers still pass easily this interlayer. Furthermore, the interlayer suppresses Dexter transfer of the phosphorescent excitons to the nonradiative triplet state of Spiro-DPVBi. Best devices reach a current efficiency of 16.3cd∕A at 100cd∕m2 and a color rendering index of 85 at warm white CIE chromaticity coordinates of (0.47, 0.42). Due to the use of electrically doped charge transport layers, 100cd∕m2 are obtained at 2.95V with a power efficiency of 17.4lm∕W.

Ultrastable and efficient red organic light emitting diodes with doped transport layers

Abstract: We demonstrate extremely stable and highly efficient red p-i-n-type organic light emitting diodes (OLEDs) based on an iridium-based electrophosphorescent dye in suitable host materials The OLEDs reach lifetimes well above 1×107h at 100cd∕m2 initial luminance and reach at the same time a performance of 124% external quantum efficiency This high lifetime is attributed to a combination of the low current density needed to reach a certain luminance and to the high stability of the materials against both charge carriers and excitons

High‐Mobility Ambipolar Transport in Organic Light‐Emitting Transistors

Abstract: Today organic materials are routinely employed for the fabrication of light-emitting devices (OLEDs) and thin-film transistors (OTFTs), with the first technological realizations already having reached the market. Moreover, OTFTs with unipolar mobility values comparable to those of amorphous silicon (1 cm V s) have now been demonstrated. Applications impacting display technologies and those sectors where low cost is a key factor and low performance is acceptable include electronic paper and radio-frequency identification (RF-ID) products. In a recent development, OTFTs also exhibiting electroluminescence (EL) have been successfully demonstrated. Organic light-emitting transistors (OLETs) represent a significant technological advance by combining two functionalities, electrical switching and light emission, in a single device, thus significantly increasing the potential applications of organic semiconductors. In particular, if appropriate materials can be introduced, OLETs offer an ideal structure for improving the lifetime and efficiency of organic light-emitting heterostructures due to the intrinsically different driving conditions and charge-carrier balance compared to conventional OLEDs. Potential applications of OLETs include flat-panel display technologies, lighting, and, ultimately, easily fabricated organic lasers. The first OLET prototypes were unipolar transport devices, and recombination was expected to take place in close proximity to the metallic drain electrode where efficiency-depleting exciton quenching is also likely to occur. To avoid this significant device deficiency and to instead generate EL nearer the center of the channel, OLETs with ambipolar charge transport would be highly desirable. Furthermore, balanced ambipolar conduction is crucial for maximizing exciton recombination through efficient electron–hole balancing. Up to now various solutions have been proposed: single ambipolar materials and two-component coevaporated or layered structures. In coevaporated films, two materials are simultaneously sublimed to form bulk heterojunctions. However, carrier transport is unbalanced and the mobility values are below 10 cm V s. Devices employing a polymer film showing intrinsic ambipolar transport have also been reported but with mobility values for both charge carriers around 10 cm V s. In this paper we report OLETs based on two-component layered structures that have balanced ambipolar transport and mobility values as large as 3 × 10 cm V s. These devices are realized by sequentially depositing p-type (a,x-dihexyl-quaterthiophene, DH4T) and n-type films (N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide, PTCDIC13H27, P13). The combination with the highest mobility and most-balanced transport is obtained with DH4T grown in direct contact with the dielectric. For comparison, we have also employed pentacene in place of DH4T as the p-type material and showed that unbalanced ambipolarity is obtained. Morphological analysis of the outermost and buried layers, performed by laser scanning confocal microscopy (LSCM), allows selective imaging of materials with energetically separated photoluminescence (PL) spectra. Importantly, it is shown that ‘growth compatibility’ between the nand p-type materials is essential in forming a continuous interface and thereby controlling the resulting OLET optoelectronic-response properties. Each OLET material was first evaluated in a single layer in a top source–drain contact OTFT. As substrates we employed heavily doped silicon wafers with thermally grown oxides. Surface treatments such as octadecyltrichlorosilane or hexamethyldisilazane did not result in substantial improvement in the device performance. Parameters such as substrate temperature (Tsub) and evaporation rate were varied to optimize electrical characteristics. The optimum growth conditions were found to be: Tsub = 90 °C and rate = 0.1 A s –1 for DH4T, and Tsub = 25 °C and rate = 0.1 A s –1 for P13. In Table 1, the mobility (l) and threshold-voltage (Vth) values obtained are summarized. These are comparable to the highest values reported in the literature. The DH4T devices were stable even C O M M U N IC A TI O N S

Platinum Binuclear Complexes as Phosphorescent Dopants for Monochromatic and White Organic Light‐Emitting Diodes

Abstract: Efficient blue-, green-, and red-light-emitting organic diodes are fabricated using binuclear platinum complexes as phosphorescent dopants. The series of complexes used here have pyrazolate bridging ligands and the general formula C^NPt(μ-pz) 2 PtC^N (where C^N = 2-(4',6'-difluorophenyl)pyridinato-N,C 2' , pz = pyrazole (1), 3-methyl-5-tert-butylpyrazole (2), and 3,5-bis(tert-bu-tyl)pyrazole (3)). The Pt-Pt distance in the complexes, which decreases in the order 1>2>3, solely determines the electroluminescence color of the organic light-emitting diodes (OLEDs). Blue OLEDs fabricated using 8 % 1 doped into a 3,5-bis(N-carbazolyl)benzene (mCP) host have a quantum efficiency of 4.3 % at 120 Cd m -2 , a brightness of 3900 Cd m -2 at 12 V, and Commission Internationale de L'Eclairage (CIE) coordinates of (0.11, 0.24). Green and red OLEDs fabricated with 2 and 3, respectively. also give high quantum efficiencies (-6.7%), with CIE coordinates of (0.31, 0.63) and (0.59, 0.46), respectively. The current-density-voltage characteristics of devices made using dopants 2 and 3 indicate that hole trapping is enhanced by short Pt-Pt distances (< 3.1 A). Blue electrophosphorescence is achieved by taking advantage of the binuclear molecular geometry in order to suppress dopant intermolecular interactions. No evidence of low-energy emission from aggregate states is observed in OLEDs made with 50 % 1 doped into mCP. OLEDs made using 100 % 1 as an emissive layer display red luminescence, which is believed to originate from distorted complexes with compressed Pt-Pt separations located in defect sites within the neat film. White OLEDs are fabricated using 1 and 3 in three different device architectures, either with one or two dopants in dual emissive layers or both dopants in a single emissive layer. All the white OLEDs have high quantum efficiency (∼5 %) and brightness (∼600 Cd m -2 at 10 V).

New Charge Transporting Host Material for Short Wavelength Organic Electrophosphorescence: 2,7-Bis(diphenylphosphine oxide)-9,9-dimethylfluorene

Abstract: We report the synthesis, crystal structure, and photophysical and electroluminescent properties of a new charge transporting host material for short wavelength phosphor-doped organic light emitting devices (OLEDs) based on 2,7-bis(diphenylphosphine oxide)-9,9-dimethylfluorene (PO6). The PO moiety is used as a point of saturation between the fluorene bridge and the outer phenyl groups so that the triplet exciton energy of PO6 is 2.72 eV, similar to that of a dibromo substituted fluorene, but it is more amenable to vacuum sublimation and has good film forming properties. Computational analysis (B3LYP/6-31G*) predicts the highest occupied molecular orbital and lowest unoccupied molecular orbital energies of PO6 to be lower by 1.5 and 0.59 eV, respectively, compared to a similar diphenylamino substituted derivative. In a simple bilayer OLED device, PO6 exhibits structured UV electroluminescence at a peak wavelength of 335 nm and structured lower energy emission with peaks at 380 and 397 nm, similar to the sol...

Highly efficient white organic light-emitting diode

Abstract: We present a highly efficient white electroluminescence device by the combination of a solution processed blue organic phosphorescence light-emitting diode with appropriate down-conversion phosphor system. The use of this down-conversion system produced an extraordinary enhancement on device performance, resulting in a white electroluminescence device with luminance efficacy of 25lm∕W at luminance efficiency reaching 39cd∕A. The extraordinary enhancement on device performance is attributed to isotropic radiation pattern of the excited phosphor particles, leading to high light extraction properties.

Organic light-emitting display

Abstract: An organic light-emitting display (OLED) includes a first substrate, a first organic light-emitting pixel area, a first driver, a second substrate, a system circuitry, and a conductive member. The second substrate is opposite to the first substrate. The first organic light-emitting pixel area is defined on the first substrate and is sealed between the first substrate and the second substrate. The first driver disposed on the first substrate is used for driving the first organic light-emitting pixel area to generate images. The system circuitry disposed on the second substrate is for electrically connected to the first driver. The first substrate and the second substrate are electrically connected with each other through the conductive member.

Amorphous diphenylaminofluorene-functionalized iridium complexes for high-efficiency electrophosphorescent light-emitting diodes

Abstract: Two new phosphorescent iridium(111) cyclometalated complexes, [Ir(DPA-Flpy) 3 ] (1) and [Ir(DPA-Flpy) 2 (acac)] (2) ((DPA-Flpy)H = (9,9-diethyl-7-pyridinylfluoren-2-yl)diphenylamine, Hacac = acetvlacetone), have been synthesized and chaaracterized. The incorporation of electron-donating diphenylamino groups to the fluorene skeleton is found to increase the highest occupied molecular orbital (HOMO) levels and add hole-transporting ability to the phosphorescent center. Both complexes are highly amorphous and morphologically stable solids and undergo glass transitions at 160 and 153°C. respectively. These iridium phosphors emit bright yellow to orange light at room temperature with relatively short lifetimes (< 1 μs) in both solution and the solid state. Organic light-emitting diodes (OLEDs) fabricated using 1 and 2 as phosphorescent dopant emitters constructed with a multilayer configuration show very high efficiencies. The hoinoleplic iridium complex 1 is shown to be a more efficient electrophosphor than the heleroleptic congener 2. Efficient electrophosphorescence with a maximum external quantum efficiency close to 10 % ph/el (photons per electron), corresponding to a luminance efficiency of ∼30 cd A -1 and a power efficiency of ∼21 1m W -1 , is obtained by using, 5 wot.-% 1 as the guest dopant.

Flexible AM OLED panel driven by bottom-contact OTFTs

Abstract: Active matrix organic-light-emitting-diode (AM OLED) panels, driven by organic thin-film transistors (OTFT), have been successfully fabricated on a flexible plastic substrate. The pixel circuit consists of two bottom-contact pentacene OTFTs working as switching and driving transistors. The panel has 16 /spl times/ 16 pixels, each of which have an OLED using a phosphorescent material with an emission efficiency of 30 cd/A. A tantalum oxide (Ta/sub 2/O/sub 5/) film with a dielectric constant of 24, prepared by the anodization of Tantalum (Ta), was used as the gate insulator of the OTFTs. The passivation layer on the OTFTs was formed by a layer of silicon dioxide (SiO/sub 2/) and two layers of polyvinyl alcohol. Using OTFTs with a Ta/sub 2/O/sub 5/ gate insulator, the authors have realized a flexible active matrix OLED panel driven with a low voltage of -12 V.

P‐185: Low‐Drive‐Voltage OLEDs with a Buffer Layer Having Molybdenum Oxide

Abstract: In this paper, we introduce a useful composite layer, comprising hole-transporting materials with molybdenum oxide. By using the composite as a buffer layer on an anode, an OLED with low drive voltage can be obtained, and pixel defect formation can be effectively suppressed.

Organic element for low voltage electroluminescent devices

Abstract: An OLED device comprises a cathode, a light emitting layer and an anode, in that order, and comprising; (i) in the light-emitting layer at least one light emitting compound selected from amine containing monostyryl, amine containing distyryl, amine containing tristyryl and amine containing tetrastyryl compounds, and (ii) a further layer located between the cathode and the light emitting layer, containing (a) 10-volume % or more of a carbocyclic fused ring aromatic compound, and (b) at least one salt or complex of a Group IA, IIA, IIIA or IIB element of the Periodic Table. Such devices exhibit reduce drive voltage while maintaining good luminance.

Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters

Abstract: We demonstrate a white stacked organic light-emitting device (WSOLED) employing the blue fluorescent emitter, 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl, and the green and red phosphorescent emitters, fac-tris(2-phenylpyridinato-N,C2′) iridium (III) and iridium (III) bis(2-phenyl quinolyl-N,C2′) acetylacetonate, respectively. The charge generation region consists of a Li-doped electron transport layer and a highly transparent MoOx thin film. For a two-element white SOLED (2-WSOLED), the combination of red and green phosphors with a blue fluorophore yields maximum external quantum and power efficiencies of ηext=23%±2% at a current density of J=1mA∕cm2 and ηp=14±1lm∕W at J=0.17mA∕cm2, respectively. Due to the low optical and electrical losses of the charge generation layer, the efficiencies scale approximately linearly with the number of independent emissive elements in the WSOLED. Hence, for a 3-WSOLED, the total external and power efficiencies estimated for operation of the device in a light fixtur...

Organic light-emitting diodes having exclusive near-infrared electrophosphorescence

Abstract: Near-infrared (NIR) emission is demonstrated from phosphorescent organic light-emitting diodes containing blends of polymeric host and heavy metal complex, iridium(III) bis(1-pyrenyl-isoquinolinato-N,C′) acetylacetonate. The devices exhibit exclusive NIR emission with a peak value at 720nm. Forward light output exceeds 100μW∕cm2, and the external quantum efficiency is nearly 0.1%. These values are shown to increase upon using a hole blocking layer in the device architecture.

Stable inverted bottom-emitting organic electroluminescent devices with molecular doping and morphology improvement

Abstract: Stable inverted bottom-emitting organic light-emitting diodes (IBOLEDs) have been investigated by inserting n-type Cs2O dopant between indium-tin oxide bottom cathode and Alq3, the combination of which not only improved the morphology of organic layer but enhanced the lifetime of the IBOLED. This n-type doped IBOLED achieved efficiencies of 5.2cd∕A and 2.0lm∕W at 20mA∕cm2. The 20% decay lifetime (t80) of Cs2O doped IBOLED is 270h which is about 1.7 times more stable than that of the conventional OLED (160h) and 2.5 times of Li doped IBOLED (104h).

Efficient white-light-emitting diodes based on poly(N-vinylcarbazole) doped with blue fluorescent and orange phosphorescent materials

Abstract: We have fabricated polymer white-light-emitting devices possessing a single emitting layer containing a hole-transporting host polymer, poly(N-vinylcarbazole), and an electron-transporting auxiliary, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, doped with a blue-light-emitting amino-substituted distyrylarylene fluorescent dye and an orange-light-emitting osmium phosphor. The doubly doped device exhibited an intense white emission having Commission Internationale de l’Eclairage coordinates of (0.33, 0.34), a high external quantum efficiency of 6.12% (13.2cd∕A), and a maximum brightness of 11306cd∕m2. The color coordinates remained unchanged over a range of operating voltages, even at luminance as high as 1×104cd∕m2.