白色有机发光材料与器件

综述了白色有机电致发光材料和器件的研究进展;归纳了获取白色有机电致发光的途径和方法;分析了多种器件结构的特点及其材料;结合研究过程中存在的某些问题,从器件的发光效率和色纯度角度,讨论了影响发光器件性能的诸因素及其改进措施.     

Thermally stable triphenylene-based hole-transporting materials for organic light-emitting devices

The thermally stable hole transport layer (HTL) materials, 1,4-bis[(N,N′-di(2-naphthyl)-N,N′-diphenyl)aminophenyl]triphenylene (NPAPT) and 1,4-bis[(N,N′-di(2-naphthyl)-N,N′-diphenyl) aminophenyl]-2,3-diphenyl triphenylene (NPAPPT), were synthesized and the device performances of the organic light-emitting diodes (OLEDs) with NPAPT and NPAPPT as a hole transport layer were investigated. The glass transition temperatures of NPAPT and NPAPPT could be enhanced to 153 °C and 157 °C by the introduction of a rigid triphenylene backbone in the main chain. The use of NPAPT and NPAPPT as a HTL for OLEDs lowered the driving voltage and enhanced the light-emitting efficiency. The power efficiencies of triphenylene-based devices with tris(8-hydroxyquinoline)aluminum as an emitting material could be improved by 20% compared with that of N,N′-di(naphthalene-1-yl)-N,N′-diphenyl benzidine based devices.     

Recent progresses on materials for electrophosphorescent organic light-emitting devices

Although organic light-emitting devices have been commercialized as flat panel displays since 1997, only singlet excitons were emitted. Full use of singlet and triplet excitons, electrophosphorescence, has attracted increasing attentions after the premier work made by Forrest, Thompson, and co-workers. In fact, red electrophosphorescent dye has already been used in sub-display of commercial mobile phones since 2003. Highly efficient green phosphorescent dye is now undergoing of commercialization. Very recently, blue phosphorescence approaching the theoretical efficiency has also been achieved, which may overcome the final obstacle against the commercialization of full color display and white light sources from phosphorescent materials. Combining light out-coupling structures with highly efficient phosphors (shown in the table-of-contents image), white emission with an efficiency matching that of fluorescent tubes (90 lm/W) has now been realized. It is possible to tune the color to the true white region by changing to a deep blue emitter and corresponding wide gap host and transporting material for the blue phosphor. In this article, recent progresses in red, green, blue, and white electrophosphorescent materials for OLEDs are reviewed, with special emphasis on blue electrophosphorescent materials.     

Thermally stable carbazole-diimides as hole transport materials for organic light-emitting devices

We synthesized new carbazole-diimide hole-transporting materials with different dianhydride groups by thermal imidization. The imide moieties were introduced to improve thermal stability of a carbazole hole transport molecule. Result showed that the carbazole-diimdes exhibit good thermal stability with glass transition temperature of 142-182 degrees C and degradation temperature of approximately 450 degrees C as well as good optical transparency in the visible region. The organic light-emitting device (OLED) using alicyclic diimide (CBCZ) shows maximum luminance approximately 8,600 cd/m2 at 12 V and current efficiency of 2.1 cd/A. With optimization of fabricating conditions, the thermally stable CBCZ is expected to be used as a promising hole-transporting material with higher efficiency and durability.     

Prototyping of microfluidic devices in poly(dimethylsiloxane) using solid-object printing

A solid-object printer was used to produce masters for the fabrication of microfluidic devices in poly(dimethylsiloxane) (PDMS). The printer provides an alternative to photolithography for applications where features of > 250 microm are needed. Solid-object printing is capable of delivering objects that have dimensions as large as 250 x 190 x 200 mm (x, y, z) with feature sizes that can range from 10 cm to 250 microm. The user designs a device in 3-D in a CAD program, and the CAD file is used by the printer to fabricate a master directly without the need for a mask. The printer can produce complex structures, including multilevel features, in one unattended printing. The masters are robust and inexpensive and can be fabricated rapidly. Once a master was obtained, a PDMS replica was fabricated by molding against it and used to fabricate a microfluidic device. The capabilities of this method are demonstrated by fabricating devices that contain multilevel and tall features, devices that cover a large area (approximately 150 cm2), and devices that contain nonintersecting, crossing channels.     

Red polymer light-emitting devices based on an oxadiazole-functionalized europium(III) complex

A novel tris(dibenzoylmethanato)[5-(2-(4-tert-butylbenzenyl)-5-benzenyl-1,3,4-oxadiazole-4′)-1,10-phenanthroline]europium(III) [Eu(DBM)₃(BuOXD-Phen)] containing an electron-transporting oxadiazole-functionalized phenanthroline ligand was synthesized and characterized. Its UV–vis absorption and photoluminescence (PL), as well as the electroluminescence (EL) in polymer light-emitting devices (PLEDs) were investigated. The double-layer PLEDs with a configuration of ITO/PEDOT:PSS (50 nm)/PVK (40 nm)/PFO:PBD (30%):Eu(DBM)₃(BuOXD-Phen) (1–8 wt %) (80 nm)/Ba (4 nm)/Al (150 nm) were fabricated. Saturated red Eu³⁺ ion emission, based on the ⁵D₀ → ⁷F₂ transition, is centered at a wavelength of 614 nm with a full width at half maximum (FWHM) of 10 nm. The highest external quantum efficiency (QE_ext) of 1.26% at current density of 1.65 mA cm⁻², with a maximum brightness of 568 cd m⁻² at 137.8 mA cm⁻² was achieved from the device at 1 wt % dopant concentration.     

Solvent compatibility of poly(dimethylsiloxane)-based microfluidic devices

This paper describes the compatibility of poly(dimethylsiloxane) (PDMS) with organic solvents; this compatibility is important in considering the potential of PDMS-based microfluidic devices in a number of applications, including that of microreactors for organic reactions. We considered three aspects of compatibility: the swelling of PDMS in a solvent, the partitioning of solutes between a solvent and PDMS, and the dissolution of PDMS oligomers in a solvent. Of these three parameters that determine the compatibility of PDMS with a solvent, the swelling of PDMS had the greatest influence. Experimental measurements of swelling were correlated with the solubility parameter, delta (cal(1/2) cm(-3/2)), which is based on the cohesive energy densities, c (cal/cm(3)), of the materials. Solvents that swelled PDMS the least included water, nitromethane, dimethyl sulfoxide, ethylene glycol, perfluorotributylamine, perfluorodecalin, acetonitrile, and propylene carbonate; solvents that swelled PDMS the most were diisopropylamine, triethylamine, pentane, and xylenes. Highly swelling solvents were useful for extracting contaminants from bulk PDMS and for changing the surface properties of PDMS. The feasibility of performing organic reactions in PDMS was demonstrated by performing a Diels-Alder reaction in a microchannel.     

Progress towards ultrasound applications of new single crystal materials

In recent years, single crystal materials with better piezoelectric properties than the existing ceramics have become available. These new materials will potentially provide improved performance in ultrasonic applications such as NDT, sonar and biomedical diagnosis. In order to select the best material and optimize transducer design, comparison must be carried out. However, due to material and transducer fabrication costs, initial comparisons can be based on simulation. In this paper, a comparison is reported between transducers based on the single crystal lead magnesium niobate-lead titanate (PMN-32% PT) and the ceramic lead zirconate titanate (PZT-5H). Material performance is assessed both for single materials and piezoelectric-polymer composite configurations by defining the relevant piezoelectric parameters. Furthermore, the effect of such parameters on the performance of different ultrasonic transducers is illustrated. Practical limitations are also discussed. We conclude that the new single crystal material will be capable of outperforming the present widely used ceramic for almost all practical applications.     

生物质基聚丁二酸丁二醇酯(PBS)应用研究进展

由于石油资源的日益枯竭,通过生物资源发酵得到琥珀酸来生产聚丁二酸丁二醇酯(PBS),以替代现在石油基产品为原料的PBS,是PBS产业发展的新方向,丁二酸发酵的商业化促进了生物质基PBS的发展和应用,通过对PBS进行各种改性以及加工成型,制得各类制品,使PBS产品能够应用于不同领域,生物质基PBS作为一种绿色塑料具有广阔的发展前景。     

Progress towards ultrasound applications of new single crystal materials

In recent years, single crystal materials with better piezoelectric properties than the existing ceramics have become available. These new materials will potentially provide improved performance in ultrasonic applications such as NDT, sonar and biomedical diagnosis. In order to select the best material and optimize transducer design, comparison must be carried out. However, due to material and transducer fabrication costs, initial comparisons can be based on simulation. In this paper, a comparison is reported between transducers based on the single crystal lead magnesium niobate-lead titanate (PMN-32% PT) and the ceramic lead zirconate titanate (PZT-5H). Material performance is assessed both for single materials and piezoelectric-polymer composite configurations by defining the relevant piezoelectric parameters. Furthermore, the effect of such parameters on the performance of different ultrasonic transducers is illustrated. Practical limitations are also discussed. We conclude that the new single crystal material will be capable of outperforming the present widely used ceramic for almost all practical applications.     

Highly efficient red phosphorescent organic light-emitting devices using iridium(III) complexes based on 2-(biphenyl-3-yl)quinoline derived ligands

Red phosphorescent emitters were synthesized based on Ir(III) phenylquinoline complexes for applications to OLEDs. Ir(III) complexes 1-3 were based on 2-(biphenyl-3-yl)-quinoline units connected to various phenyl groups such as 5-phenyl, 5-(4-fluorophenyl), and 6-phenyl groups. The EL efficiencies were quite sensitive to the structural features of the dopants in the emitting layers. In particular, a high-efficiency red OLED was fabricated using complex 1 as the dopant in the emitting layer. This OLED showed a maximum luminance, luminous efficiency, power efficiency, external quantum efficiency and CIE(x,y) coordinates of 21,600 cd/m2 at 16 V, 11.80 cd/A at 20 mA/cm2, 3.57 Im/W at 20 mA/cm2, 10.90% at 20 mA/cm2, and (x = 0.63, y = 0.32) at 12 V, respectively.     

TMEP作为缓冲层增加有机发光器件的效率的研究

在有机发光器件中的发光层和阴极之间插入了稳定性好、有良好电子传输能力的苝酸四甲酯(TMEP)新型缓冲层,改善了有机电致发光器件的亮度和发光效率.在电流密度为200mA/cm2时,有缓冲层的器件B效率为0.82cd/A,没有缓冲层的器件A效率为0.14cd/A.     

Synthesis and characterization of stannane-terminated poly(silole-co-germole) for the evaluation of luminescent polymeric light-emitting diode

Codehydrocoupling (with various inorganic hydrides) followed by stannane-capping (with Ph2SnHCI) of 1,1-dihydrotetraphenylsilole (1) and 1,1-dihydrotetraphenylgermole (2) (9:1 mol ratio) produces electroluminescent stannane-terminated poly(silole-co-germole)s (3) in high yield. The polymerization yield and molecular weight with Selectride increase in the order L-Selectride < N-Selectride < K-Selectride. The molecular weights increase in the order L-Selectride < Red-Al < N-Selectride < K-Selectride < Super-Hydride. The copolymer 3, a good candidate for PLED fabrication, emits at 523 nm and are electroluminescent at 521 nm. The fluorescence quantum yield of 3 in toluene is (1.61 +/- 0.29) x 10(-2). The emission color is green. The maximum brightness of the device is 3,750 cd/m2 with a luminous power efficiency of 0.67 Im/W.     

Tin oxide as a transparent electrode material for light-emitting diodes fabricated with poly (p-phenylene vinylene)

We have fabricated light emitting diodes (LED) with poly (p-phenylene vinylene) (PPV) as the emissive layer and tin oxide (TO) as the transparent conducting positive electrode and aluminium as the negative electrode. The fabrication conditions are optimized for visible light emission in these TO/PPV/Al LEDs. The threshold voltage for substantial charge injection for visible light emission in these LEDs lies below 10V. The device fabrication and electrical characterization of TO/PPV/Al LEDs are discussed in this communication.     

Composite electronic materials based on poly(3,4-propylenedioxythiophene) and highly charged poly(aryleneethynylene)-wrapped carbon nanotubes for supercapacitors

Supercapacitor charge storage media were fabricated using the semiconducting polymer poly(3,4-propylenedioxythiophene) (PProDOT) and single-walled carbon nanotubes (SWNTs) that were helically wrapped with ionic, conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES). These PNES-wrapped SWNTs (PNES-SWNTs) enable efficient dispersion of individualized nanotubes in a wide range of organic solvents. PNES-SWNT film-modified Pt electrodes were prepared by drop casting PNES-SWNT suspensions in MeOH; high stability, first-generation PProDOT/PNES/SWNT composites were realized via electropolymerization of the ProDOT parent monomer (3,4-propylenedioxythiophene) in a 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/propylene carbonate solution at the PNES-SWNT-modified electrode. The electrochemical properties of PProDOT and PProDOT/PNES/SWNT single electrodes and devices were examined using cyclic voltammetric methods. The hybrid composites were found to enhance key supercapacitor figures of merit (charge capacity and capacitance) by approximately a factor of 2 relative to those determined for benchmark Type I devices that exploited a classic PProDOT-based electrode material. The charge/discharge stability of the supercapacitors was probed by repeated rounds of cyclic voltammetric evaluation at a minimum depth of discharge of 73%; these experiments demonstrated that the hybrid PProDOT/PNES/SWNT composites retained ~90% of their initial charge capacity after 21,000 charge/discharge cycles, contrasting analogous data obtained for PProDOT-based devices, which showed only 84% retention of their initial charge capacity.     

聚苯并咪唑树脂的合成进展

介绍了聚苯并咪唑树脂的性能、用途及合成工艺。并详细论述了不同种类聚苯并咪唑树脂的研究状况。     

In-line deposition of organic light-emitting devices for large area applications

Light-emitting diodes based on organic semiconductors show promising features for display and lighting applications. A vertical in-line deposition technique for organic light-emitting diode (OLED) manufacturing was developed.OLED devices with electrically doped transport layers show low operating voltage, high efficiency and long lifetime. The preparation of p-i-n type devices was performed with the in-line fabrication tool resulting in highly efficient OLED with low operating voltage. The lowest operating voltage was achieved for green diodes with 2.9 V for 100 cd/m². This demonstrates that the p-i-n device concept can be applied under manufacturing conditions. In-line manufactured highly efficient red, green and blue OLED are presented.One important aspect for fabrication cost is the used ground contact, which is commonly made by indium tin oxide (ITO). For low cost fabrication an alternative for ITO has to be used. In this work, ITO was replaced by aluminium doped zinc oxide (ZAO). The results are comparable to OLEDs using ITO as transparent conductive oxide.     

New oxadiazole complex with bipolar ligand for organic light-emitting devices

New oxadiazole complex with bipolar ligand, Zn(POTPA)₂, was designed and synthesized, and used as an emitter material in single-layer organic electroluminescent (EL) devices (OLED). The UV absorbance of Zn(POTPA)₂ is caused by electron π–π^? transition. Zn(POTPA)₂ exhibited strong blue luminescence in solution and film. Compared with triphenylamine and 2,5-diphenyl-1,3,4-oxadiazole, cyclic voltammograms exhibited that Zn(POTPA)₂ has bipolar properties, and the optical band gap energy, Eg, calculated based on the cyclic voltammograms is nearly equal to that deduced from the absorption spectrum. Single-layer device with the structure of ITO/Zn(POTPA)₂/Mg:Ag were fabricated and blue electroluminescence was observed with a maximum luminance of 271 cd/m² and efficiency of 0.46 cd/A.