聚合物顶发射发光二极管的研究

采用铬(Cr)作为聚合物顶发射发光二极管阳极,得到了一种高效的顶发射发光器件结构。在使用铬作为器件阳极时,首先使用磁控溅射方法使其沉积在玻璃衬底表面,然后使用不同厚度PEDOT:PSS薄膜提高阳极表面的平整度,并得出当PEDOT:PSS厚度为60nm时器件具有最高效率。本实验采用聚合物P-PPV(poly[2-(4-3’,7’-dimethyloctyloxy)-phenyl]-p-pheny-lenevinylene))作为发光层。器件阴极结构为钡/银(Ba/Ag),通过不同厚度阴极的器件对比,得出阴极最适合的结构为Ba(4nm)/Ag(15nm)。此时,该结构的器件最大效率达4.41cd/A,最大效率时亮度达到738cd/m2。     

Transparent Conducting Electrodes for Quantum Dots Light Emitting Diodes

In this review, we briefly describe a recent research development of transparent conducting electrodes (TCEs) for next‐generation quantum dot‐based light‐emitting diodes (QDLEDs). Although sputtered Sn‐doped In₂O₃ (ITO) and chemically grown F‐doped SnO₂ (FTO) electrodes have mainly been employed as transparent electrodes for QDLEDs, there have been great advances in TCE materials and fabrication processes. This review presents important characteristics of various TCE and applications in QDLEDs as a transparent cathode or anode. In particular, we will focus on characteristics of metal grids, metal nanowire, carbon nanotube, graphene, and hybrid electrodes for QDLEDs as promising alternatives to typical ITO and FTO electrodes. In addition, we discuss the current status of transparent conducting oxide‐based QDLEDs. By comparing the performances of QDLED with different TCEs, we suggest promising alternatives ITO or FTO electrodes.     

高功函数金属Al作阴极的高效率白光聚合物电致发光

我们用聚电解质PFN做电子注入层,制备了高功函数金属Al做阴极的高效率白光聚合物电致发光。以蓝绿光发光中心的聚合物为主体和掺杂红光磷光染料,通过改变红磷光的掺杂浓度调节器件的电致发光光谱,得到白光发射。并研究了电子传输材料对WILLED器件发光光谱的影响。     

Antimicrobial Combined Action of Graphene Oxide and Light Emitting Diodes for Chronic Wound Management

Innovative non-antibiotic compounds such as graphene oxide (GO) and light-emitting diodes (LEDs) may represent a valid strategy for managing chronic wound infections related to resistant pathogens. This study aimed to evaluate 630 nm LED and 880 nm LED ability to enhance the GO antimicrobial activity against Staphylococcus aureus- and Pseudomonas aeruginosa-resistant strains in a dual-species biofilm in the Lubbock chronic wound biofilm (LCWB) model. The effect of a 630 nm LED, alone or plus 5-aminolevulinic acid (ALAD)-mediated photodynamic therapy (PDT) (ALAD-PDT), or an 880 nm LED on the GO (50 mg/l) action was evaluated by determining the CFU/mg reductions, live/dead analysis, scanning electron microscope observation, and reactive oxygen species assay. Among the LCWBs, the best effect was obtained with GO irradiated with ALAD-PDT, with percentages of CFU/mg reduction up to 78.96% ± 0.21 and 95.17% ± 2.56 for S. aureus and P. aeruginosa, respectively. The microscope images showed a reduction in the cell number and viability when treated with GO + ALAD-PDT. In addition, increased ROS production was detected. No differences were recorded when GO was irradiated with an 880 nm LED versus GO alone. The obtained results suggest that treatment with GO irradiated with ALAD-PDT represents a valid, sustainable strategy to counteract the polymicrobial colonization of chronic wounds.     

金属氧化物/聚合物异质结构电致发光

异质结构聚合物电致发光（HyLEDs）是近几年来聚合物电致发光研究的热点,其典型结构是将金属氧化物半导体材料用作聚合物电致发光器件（PLEDs）的载流子传输和注入层。本文概述了HyLEDs相对传统PLEDs的优势,分别从金属氧化物在PLEDs的阳极和阴极两个方面的应用对HyLEDs的研究进展进行了回顾,探讨了HyLEDs的工作机理,并对它的应用前景作出展望。     

Influence of Green,Red and Blue Light Emitting Diodes on Multiprotein Complex Proteins and Photosynthetic Activity under Different Light Intensities in Lettuce Leaves (Lactuca sativa L.)

The objective of this study was to investigate the response of light emitting diodes (LEDs) at different light intensities (70 and 80 for green LEDs, 88 and 238 for red LEDs and 80 and 238 μmol m⁻² s⁻¹ for blue LEDs) at three wavelengths in lettuce leaves. Lettuce leaves were exposed to (522 nm), red (639 nm) and blue (470 nm) LEDs of different light intensities. Thylakoid multiprotein complex proteins and photosynthetic metabolism were then investigated. Biomass and photosynthetic parameters increased with an increasing light intensity under blue LED illumination and decreased when illuminated with red and green LEDs with decreased light intensity. The expression of multiprotein complex proteins including PSII-core dimer and PSII-core monomer using blue LEDs illumination was higher at higher light intensity (238 μmol m⁻² s⁻¹) and was lowered with decreased light intensity (70–80 μmol m⁻² s⁻¹). The responses of chloroplast sub-compartment proteins, including those active in stomatal opening and closing, and leaf physiological responses at different light intensities, indicated induced growth enhancement upon illumination with blue LEDs. High intensity blue LEDs promote plant growth by controlling the integrity of chloroplast proteins that optimize photosynthetic performance in the natural environment.     

Simple and Fast Organic Device Encapsulation Using Polyisobutene

Summary: We demonstrate the use of polyisobutene (PIB) in a glass encapsulation method suitable for organic devices. The PIB viscosity at environmental temperatures provides a fast and non‐aggressive passivant layer formation method for device protection with glass. Due to its fully aliphatic character, PIB is suitable for passivating organic light‐emitting and photovoltaic devices. The observed preservation of encapsulated Ca films demonstrates the PIB suitability for air‐unstable metals passivation. Stable I(V) characteristics and increased operational lifetime were observed in PIB‐encapsulated organic devices. This encapsulation method is cheap, simple, and dispenses intensive equipment use, so that it is appropriate even for laboratories with restricted experimental facilities.

Setup used for Ca samples testing. The right Ca contact was encapsulated with PIB and a glass cover plate (dashed square). The electrical diagram of the apparatus used to obtain the resistance behavior is also shown.     

LED封装用高分子材料的研究进展

综述了国内外发光二极管（LED）封装用高分子材料的研究进展,包括环氧树脂、改性环氧树脂、有机硅树脂等,指出了今后功率型LED封装用高分子材料的研究方向,认为高性能有机硅树脂将成为高端LED封装材料的封装方向之一。     

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

A series of triarylaminooxadiazole‐containing tetraphenylsilane light emitting polymer (PTOA) and poly(2‐methoxy, 5‐(2′‐ethyl‐hexyloxy)‐p‐phenylene‐vinylene) (MEH‐PPV) based white light emitting polymer devices (PLEDs) were fabricated to study blue and orange–red emitter composition and light emitting layer processing effects on white emission electroluminescence properties. Color purity, current turn‐on voltage, brightness, and current efficiency were strongly determined by MEH‐PPV content and the thin film processing condition. The intensity of PTOA blue emission was equal to that of MEH‐PPV orange–red emission when the device was fabricated by a polymer composite film containing 10 wt % of MEH‐PPV. Color purity [Commission Internationale de L'Eclairage (CIE_x,y) coordinates (0.26,0.33)] was nearly white emission under applied 8 V. The brightness and current efficiency of PTOA‐MEH‐PPV composite film based devices increased as MEH‐PPV content increased. Furthermore, white emission blue shifted with increasing spin‐rate of thin film coating and applied voltage. Low turn‐on voltage, high current density, and high brightness were obtained for the device fabricating with light emitting layer coating with high spin‐rate. Moreover, low current efficiency was obtained for the PLED with a thinner light‐emitting layer. A white emission CIE (0.28,0.34) was obtained for PTOA‐MEH‐PPV based white PLED. White PLED brightness and efficiency can be as high as 700 cd/m² and 0.78 cd/A, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and properties of a soluble conjugated polymer,poly(2‐methoxy‐5‐N‐butoxy‐p‐phenylene vinylene)

The synthesis of poly(2‐methoxy‐5‐n‐butoxy‐p‐phenylene vinylene) (MBPPV) via a dehydrochlorination of 2‐methoxy‐5‐n‐butoxy‐α,α′‐dichloro‐p‐xylene is described. The soluble polymer was characterized by elemental analysis, Fourier transform infrared (FTIR), ¹H nuclear magnetic resonance (NMR), and UV‐visible spectroscopy. The energy gap (Eg) of the polymer was 2.53 eV determined by cyclic voltammogram. Light‐emitting diode (LED) and light‐emitting electrochemical cell (LEC) with the polymer were fabricated. The LED displayed unipolar I‐V dependence with the turn‐on voltage at 4.2 V. I‐V curve of the LEC with poly(ethylene oxide) (PEO, Mw 2 × 10⁴) displayed mirror symmetry with the turn‐on voltage at 2.7 V, but to the device with PEO (Mw 5 × 10⁶) no mirror symmetry was observed, the turn‐on voltages at +2.7 V, −11.5 V. The emission maximum of the polymer in chloroform was at λ = 550 nm, whereas the emission maxima of the LED at 5.2 V and the LEC at 4.8 V were at λ = 566, 569 nm, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2180–2185, 2000     

Synthesis of Benzothiadiazole-Based Liquid Crystalline Polyacrylates for Polarized Light Emitting Diodes

Two benzothiadiazole-based liquid crystalline polyacrylates were synthesized. These polymers revealed a nematic liquid crystal phase and exhibited photoluminescence as well as polarized electroluminescence when incorporated into light-emitting diode applications. The polymers showed dichroic ratios of about 8.3–8.8 in UV-vis absorption and photoluminescence emission. The polymer with vinylene linkages (P2) showed better electroluminescence device performance than that with acetylene linkages (P1). The P2 device emitted red light at 604 nm with a turn-on voltage at 6 V, and a maximum polarized luminance of 235 cd/m² at 12 V, with an efficiency of 0.09 cd/A and a polarization ratio of 6.5.     

Recent Advances in Encapsulation Materials for Light Emitting Diodes: a Review

Silicon - Light emitting diodes (LEDs) as the emerging green light sources are of great significance to achieve the energy saving and emission reduction. The encapsulation materials as the key...     

Light emission in phase separated conjugated and non-conjugated polymer blends

Phase separations in conjugated polymer (MEH-PPV) and non-conjugated polymer (PMMA) blended films are studied by photoluminescent (PL) near-field scanning optical microscope and spectrometer. The morphologies of blended films changed from stripe patterns to isolated islands as PMMA concentrations increased. The PL spectra in isolated micron dots are the same as MEH-PPV. Nevertheless, we found new PL spectra, peaked at 500 nm wavelength, in the PMMA matrix. Since, PMMA does not emit light, the new spectra indicate some MEH-PPV diluted in the PMMA rich regions. The excitons of MEH-PPV in the PMMA matrix are localized and emit light as PPV oligomers.     

Enhanced performance of polymer light‐emitting device via optimization of processing conditions and device configuration

The improved performance of polyalkylfluorene light‐emitting device has been achieved through the optimization of processing conditions and device configuration. The current density, brightness, power efficiency, and operation lifetime of polymer light‐emitting device (PLED) were strongly dependent on the surface treatment of anode, the film thickness of light‐emitting polymer (LEP), and the cathode configuration. The anode surface treated with O₂ plasma exhibited a higher current density and brightness than the CF₄ plasma treated device. However, better operation stability was obtained for the CF₄ plasma treated device than for the O₂ plasma treated device. The maximum of brightness and power efficiency has been achieved for the PLED with an LEP thickness of 80 nm. The PLED with LiF/Ca/Al cathode possesses a better power efficiency and operation stability than does the Ca/Al or LiF/Al based PLED. The influences of device fabrication conditions and device configuration on the performance of a polyalkylfluorene‐based PLED are discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 133–141, 2006     

聚合物电致发光材料与器件(待续)--聚合物发光材料

1990年Burroughes采用聚对苯乙炔(PPV)作为有源层制作聚合物电致发光器件,开创了共轭聚合物科学的新领域,由于聚合物电致发光器件具有制备简单、发光效率和发光亮度高、发光波长易于调节等显著特点,引起了各国的高度重视,大量的共轭聚合物材料成功地应用于电致发光器件,使得电致发光聚合物材料和器件的研究成为近年来最活跃的领域之一.     

Studies on Optical Characteristics of Multicolor Emitting MEH-PPV/ZnO Hybrid Nanocomposite

The present work endeavors towards the scientific study on influence of ZnO nanoparticles on the optical characteristics of Poly [2 Methoxy (5, 2′ Ethylhexyloxy)-P-Phenylenevinylene] (MEH-PPV), a light emitting polymer. Hybrid nanocomposites of MEH-PPV were prepared by dispersing ZnO nanorods at loading concentrations of 1 wt. % and 3 wt. %. The structural characteristics of the hybrid composites were investigated using FTIR spectroscopy and X-ray diffraction. The UV absorption spectra and Photoluminescence emission spectra were analyzed in order to study the optical characteristics of nanocomposite. The optical constants were determined and the suitability of the composites for light emission was analyzed. The incorporation of ZnO nanorods facilitates the shift in emission wavelength and witnesses the color tuning ability and multicolor emission from the composite.     

聚合物电致发光器件老化机理的研究

文章比较了聚合物pheny1-substitutedpoly[p-pheny1eneviny1ene]derivative(P-PPV)绿光电致发光器件老化前后的I-V特性曲线及亮度曲线,详细地分析了黑斑产生的可能原因。对提高聚合物电致发光器件的稳定性具有一定的指导意义。     

Synthesis,characterization, and electroluminescent properties of a novel perylene‐containing copolyimide

A novel diphenylfluorene‐based Cardo copolyimide containing perylene (PFB5) was designed and synthesized by polycondensation of a diamine 4,4′‐(9H‐fluoren‐9‐ylidene)bisphenylamine with perylene dianhydride and another dianhydride in m‐cresol with isoquinoline as a catalyst at 200°C. PFB5 was characterized by FTIR, EA, GPC, TGA, DSC, UV‐vis, and PL. Because of the existence of the bulky diphenylfluorene units in the backbone, PFB5 showed high thermal stability and good solubility in common solvents such as chloroform. Solubility of PFB5 in low boiling point solvents allows direct spin coating of the polymer films, which exhibit intense photo‐ and electroluminescence (EL) in the visible range. This nonconjugated polymer could be used as emitting and electron‐hole transporting layers in polymer electroluminescent devices (PELDs). EL properties of the unilayer ELDs based on PFB5 are discussed. The device emitted a greenish yellow light. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 786–791, 2003     

聚合物电致发光材料与器件(续完)--聚合物发光材料

1990年Burroughes采用聚对苯乙炔(PPV)作为有源层制作聚合物电致发光器件,开创了共轭聚合物科学的新领域,由于聚合物电致发光器件具有制备简单、发光效率和发光亮度高、发光波长易于调节等显著特点,引起了各国的高度重视,大量的共轭聚合物材料成功地应用于电致发光器件,使得电致发光聚合物材料和器件的研究成为近年来最活跃的领域之一.     

Nanocrystallized Organic Thin Films as Effective Light Outcoupling Layers for Organic Light-Emitting Diodes

Light outcoupling from organic light-emitting diodes (OLEDs) is essential for developing energy-saving displays and efficient lighting sources. Nanocrystallized organic thin films exhibiting scattering features have been considered as effective light extractors for OLEDs. This paper reviews recent advancements in nanocrystallized thin films and their applications in OLEDs. Due to the advantages of easy preparation and OLED compatibility, nanocrystallized organic thin films can integrate with OLEDs as external or internal light extractors easily. Significant light enhancement has been achieved. The fabrication methods and mechanisms of light enhancement are discussed.