Design of vertical fin arrays with heat pipes used for high-power light-emitting diodes

As Light-Emitting Diodes (LEDs) are negatively affected by high temperature, the thermal design for them is critical for better light quality, reliability and lifetime. In this work, a thermal design of vertical fin arrays with heat pipes as passive cooling was applied. The heat pipes can supply high thermal conductivity with much less weight and volume compared to copper or aluminum base and consequently less obstruction to air flow with enhanced natural convection. As the natural convection and radiation dominate heat transfer in this case, the optimum vertical fin spacing was calculated by the most used empirical correlations. Then, the design was numerical investigated by Computational Fluid Dynamics (CFD) to obtain best thermal performance. As the fin spacing was both optimized by correlations and modelling, the optimum thermal design achieved. Finally, we manufactured and tested the design experimentally which consistently approved the thermal design compared to correlations and simulation.     

Organo‐metal Diodes Based on a Nanoparticulate Poly(3,4‐ethylenedioxythiophene) Composite

Diodes composed of a nanoparticulate composite of poly(3,4‐ethylenedioxythiophene) and a Cu–Cu²⁺ redox couple in a poly(ethylene oxide)–LiBF₄ polymer‐electrolyte matrix between Ag and Zr electrodes show rectifications in excess of 50 000 at applied fields of 4 V. These large changes are considered to arise from both rectification at the Zr/ZrO₂ composite interface and from the switching of the composite material between two conductivity states by the application of a low potential field. The preparation and electrochemical characterisation of these novel active devices are discussed.     

从CLEO‘97会议看光电子学进展

综述了ＣＬＥＯ‘９７（国际激光器和光电子学会议）情况，扼要描述光电子学领域的重要进展，着重介绍半导体光电子学的新进展，包括大功率无铝半导体激光器、红光ＩｎＧａｎ发光二极管和激光器、量子级联激光器等。     

半导体光电子器件的研究进展

文章综述ＣＬＥＯ’９４及ＩＱＥＣ’９４会议报道的有关光电子器件的发展状况，叙述了大功率ＬＤ、蓝绿光ＬＤ、垂直腔面发射半导体激光器、可调谐ＬＤ及ＯＥＩＣ的最新研究进展。     

High performance superluminescent diodes at 1.3μm wavelength

The design,fabrication and performance of 1.3цm superluminescent diodes are reported.A InP window structure and a passive absorber waveguide in different plane are applied to suppress lasing oscillation.A buried crescent structure similar to a laser diode is introduced to achieve high output power.The output power of about 700цW is coupled into a single-mode fiber at 150mA and 25℃.Spectrum width is more than 30nm.The devices operate in superluminescent state in the range from0℃to 60℃.     

High output impedance current-mode third-order Butterworth filter topologies employing unity gain voltage buffers and equal-valued passive components

This paper presents eight new current mode third-order band pass filter topologies employing unity-gain active elements, three resistances and three capacitors. An additional topology is identical to a previously reported one, repeated here for completeness. Using equal passive components, all of the proposed topologies realize third-order BP Butterworth filter function, which can easily be converted to a LP if they are cascaded with an integrator, Therefore, without any component spread the circuits are attractive from the integration point of view. In each of the circuits, except one topology, one of the unity gain cells can be replaced by a second-generation current conveyor to pick up the output current and to obtain a high impedance output. The high output impedance provided by the current conveyor permits easy cascadability for the proposed circuits to construct high-order communication filters. Simulation and experimental results are included to verify theory.     

半导体LD在光通信以外的部分应用

文中介绍半导体激光二极管在信息传输以外的部分应用。随着激光二极管工艺和器件发展,他们在光通信以外的市场不断扩大,应用越来越广泛。本文介绍 LD 在医疗、测量、条形码扫描仪,以及光谱学方面的应用。     

Fine‐Tuning of Yellow or Red Photo‐ and Electroluminescence of Functional Difluoro‐boradiazaindacene Films

The present work describes the synthesis of difluoro‐boradiazaindacenes (Bodipy) functionalized at the central 8‐position by phenylamino moieties easily transformable into phenyl amide scaffoldings. Molecules carrying three linear or branched chains were prepared and characterized. An X‐ray crystal structure for the pivotal trimethoxyphenyl‐Bodipy derivative was determined, and the packing is discussed in terms of molecular interactions; a key feature for the formation of thin films. All of the dyes are thermally stable up to 170 °C but no liquid‐crystalline phases are observed. Reversible reduction and oxidation processes occur around +0.97 and −1.34 V, respectively, versus saturated calomel electrode in solution and the electroactivity and photoluminescence are maintained in thin films produced by vacuum evaporation. Interestingly, two distinct emissions are observed at 550 and 635 nm by electroluminescence of the trimethoxyphenyl‐Bodipy derivative, corresponding to the luminescence of isolated molecules and dimers, respectively. Doping Alq₃ films with this Bodipy molecule by vacuum evaporation produces organic light‐emitting diodes (OLEDs) in which very efficient energy transfer from the Alq₃ matrix to the Bodipy occurs by a resonance mechanism involving the first Bodipy excited state. Yellow light (550 nm, 344 cd m⁻² at 15 V) is emitted at low doping concentration (7 mol %), whereas red light (635 nm, 125 cd m⁻² at 15 V) is emitted at higher concentration (19 mol %). Dispersion of the Bodipy into a fluorescent poly(N‐vinylcarbazole) polymer (PVK) (≈3 mol % per repeating unit of PVK) by solution processing exclusively produces yellow emission owing to the isolated Bodipyfluorophore (550 nm, 213 cd m⁻² at 15 V). The second excited state of the Bodipy dye is likely involved during energy transfer from the PVK matrix.     

Hybrid organic-inorganic light-emitting diodes

The demonstration of colour tunability and high efficiency has brought organic light-emitting diodes (OLEDs) into the displays and lighting market. However, high production costs due to expensive deposition techniques and the use of reactive materials still limit their market entry, highlighting the need for novel concepts. This has driven the research towards the integration of both organic and inorganic materials into devices that benefit from their respective peculiar properties. The most representative example of this tendency is the application of metal oxides in organic optoelectronics. Metal oxides combine properties such as high transparency, good electrical conductivities, tuneable morphology, and the possibility of deposition on large areas with low-cost techniques. The use of metal oxides as charge injection interfaces in OLEDs has also been investigated. Hybrid organic-inorganic light-emitting diodes (HyLEDs) are inverted OLEDs that employ air-stable metal oxides as the charge injection contacts. They are emerging as a potential competitor to standard OLEDs, thanks to their intrinsic air stable electrodes and solution processability, which could result in low-cost, large area, light-emitting devices. This article reviews the short history of this class of devices from its first solid state example published in 2006 to the present achievements. The data presented shed light on the electronic mechanism behind the functioning of HyLEDs and give guidelines for their further optimization.