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

Abstract

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.

Structural, photoluminescence and radioluminescence properties of Eu3+ doped La2Hf2O7 nanoparticles

“…influence of OH -1 radicals and other non-radiative interactions from Eu 3+ ions endows the absolute QY to be lower than measured internal quantum yield, as noticed from our calculations. While the relative efficiency of our NPs is low when compared to standard phosphor materials, such as YAG:Ce, [54] it should be noted that low PLQYs are a general issue facing nanostructured systems. In fact, our NPs have PLQYs comparable to, and even higher than that of YAG:Eu NPs.…”

High-radiance light sources with LED-pumped luminescent concentrators applied to pump Nd:YAG passively Q-switched laser

“…The recent chip scale package (CSP) can improve considerably this parameter. In this new LED concentrator, we used LED having Our LC consist of a slabs of Ce-doped YAG, chosen in virtue of its high photoluminescence quantum yield (greater than 95% according to [8,11]) and for the good overlap between its absorption band and the emission spectrum of the blue LEDs (see Figure 3). The chosen length of our slabs is 100 mm and the thickness 1 mm (corresponding to a geometrical concentration factor G = 200).…”

Remote Pyramid-Shaped Phosphor Coating for Phosphor-Converted White LEDs

“…The internal quantum efficiency (IQE) of the YAG:Ce micro-size powder phosphor (MPP) has reached over 90% [1]. But there are two major drawbacks for current pc-LEDs in terms of package extraction efficiency.…”