Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

A light-emitting device package including: a package main body including a cavity and a lead frame including a mounting portion disposed in the cavity and a plurality of terminal portions; a light-emitting device chip mounted on the mounting portion; a plurality of bonding wires for electrically connecting the plurality of terminal portions and the light-emitting device chip; a light-transmitting encapsulation layer filled in the cavity; and a light-transmitting cap member disposed in the cavity and blocking the encapsulation layer to contact the plurality of bonding wires.

Light emitting device package

White light-emitting diodes (WLEDs) with high luminous brightness, low energy consumption, long lifetime and environmental friendliness can be applied in various fields. However, low colour rendering index and high correlated colour temperature have seriously limited the quality of white light, resulting from the deficiency of the red light component in commercial phosphors. New phosphors that can emit suitable red light are needed. The improvement of red emitters has gradually become a hot topic in WLED applications such as good colour rendering lighting and full colour displays. This review summarizes recent achievements concerning red phosphors mainly from three aspects. They are: intensifying absorption bands and reducing lattice defects to increase quantum efficiency; selecting an appropriate coordination environment and altering the lattice symmetry to fine-tune the luminescence spectra; and reducing the nonradiative transition rate and preventing charge imbalance of a luminescence centre to enhance thermal stability.

Advanced red phosphors for white light-emitting diodes

By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

Light Emitting Device

The MYTHEN single-photon-counting silicon microstrip detector has been developed at the Swiss Light Source for time-resolved powder diffraction experiments. An upgraded version of the detector has been installed at the SLS powder diffraction station allowing the acquisition of diffraction patterns over 120° in 2θ in fractions of seconds. Thanks to the outstanding performance of the detector and to the calibration procedures developed, the quality of the data obtained is now comparable with that of traditional high-resolution point detectors in terms of FWHM resolution and peak profile shape, with the additional advantage of fast and simultaneous acquisition of the full diffraction pattern. MYTHEN is therefore optimal for time-resolved or dose-critical measurements. The characteristics of the MYTHEN detector together with the calibration procedures implemented for the optimization of the data are described in detail. The refinements of two known standard powders are discussed together with a remarkable application of MYTHEN to organic compounds in relation to the problem of radiation damage.

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The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

We report on the methodology and implementation of a robust and accurate double integrating sphere system for measuring the absolute photoluminescence quantum yield and its temperature dependence of commercially available phosphors (garnets, silicates and nitrides). The potential of our instrument for the examination of light interaction with samples of different absorption and diffusion coefficients is also presented, as optical properties of luminescent materials have a major impact on the efficiency of LED’s packaging. Our work gives special attention to the control and the optimization of light losses in the optical system in order to ensure reliable measurements. The YAG:Ce phosphor shows the highest luminescence quantum yield at 97% efficiency, the green silicate the lowest with 79% efficiency. Silicate phosphors show up to 15% loss of luminescence intensity when temperature is raised to 140°C.

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Optical efficiency characterization of LED phosphors using a double integrating sphere system

R&D issues for SiCf/SiC composites structural material in fusion power reactor blankets

Thermal resistance investigations on new leadframe-based LED packages and boards

The inventive protective layer (7) consists of a metal or metal alloy absorbing important thermodynamic deformations without cracking and used for energy storage, in particular the metal or a metal alloy whose expansion ratio is lower than 610-6 °C Said protective layer can be associated with a second layer (6) made of an insulation ceramic material A coating method is also disclosed Said protection is predominantly advantageous for microbatteries (10) whose components are air-reactive

Adrien Gasse

Papers

Optical efficiency characterization of LED phosphors using a double integrating sphere system

R&D issues for SiCf/SiC composites structural material in fusion power reactor blankets

Thermal resistance investigations on new leadframe-based LED packages and boards

Layer and method for microbattery protection by a ceramic-metal double layer

Performance of the TAURO blanket system associated with a liquid-metal cooled divertor