Measuring the absolute quantum efficiency of luminescent materials

Rohwer, Lauren Shea; Martin, James E.

doi:10.1016/j.jlumin.2005.01.013

Cited by 123 publications

(50 citation statements)

References 14 publications

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“…The second is given by the conversion efficiency (CE), or quantum yield (QY), and we emphasise that these two terms are differently defined. Measurement of the absolute quantum yield of luminescent materials is described in 161,162 . Conventionally, in fluorescent photoluminescence, the term quantum yield is used which is defined as 163 :…”

Section: Conversion Efficiency and Quantum Yieldmentioning

confidence: 99%

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

2016

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Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons. This fundamentally interesting process has many applications in biomedical imaging, light source and display technology, and solar energy harvesting. In this review we discuss the underlying physical principles and their modelling using rate equations. We discuss how the understanding of photophysical processes enabled strategic influence over the optical properties of upconversion especially in rationally designed materials. We subsequently present an overview of recent experimental strategies to control and optimize the optical properties of upconversion nanoparticles, focussing on their emission spectral properties and brightness. TOC

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Section: Conversion Efficiency and Quantum Yieldmentioning

confidence: 99%

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

2016

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“…Table 1 shows QY values of silicone/phosphors samples (with 20% phosphor in weight) used in this study. This concentration was chosen as the density of phosphor particles in a 20% sample (~9 × 10 4 particles /mm 3 ) is of the same order of magnitude than the density of phosphor layers generally used in LED packages [2]. Errors on QY values are evaluated by calculating the standard deviation on the experimentally measured averaged QY values of 10 different measurements.…”

Section: Luminescence Quantum Yieldsmentioning

confidence: 99%

“…The light is reflected at the surface (specular and diffuse behavior), selectively absorbed by the phosphor, scattered by phosphor particles (differently depending on the particle size), converted to different wavelengths or transmitted through the film. That is why the accurate understanding and characterization of processes describing light and phosphor particle interaction are not straightforward [3,4]. The quantum yield (QY) of a luminescent material is defined as the ratio of the number of photons emitted to the number of photons absorbed by the irradiated sample; it characterizes a radiative transition in combination with the luminescence lifetime, luminescence spectrum and photo stability of the phosphor.…”

Section: Introductionmentioning

confidence: 99%

“…Knowledge of the QY provides a crucial feedback in the development of new synthesis techniques for the variety of luminescent materials being studied. Despite of the importance of accurate evaluation of luminescence quantum yields, very few studies addressing phosphor absolute QY values and measurement methodologies can be found in literature [3][4][5]. In these references, photoluminescence quantum yield value for the yellow YAG:Ce phosphor is often loosely defined as being higher than 90%.…”

Section: Introductionmentioning

confidence: 99%

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

2015

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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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“…1. In the end, VTDs produced by contact with the substrate are confined to mesa areas, but the cantilever regions over trenches DE-FC26-01NT41251 p. 10 Final Report have very low dislocation densities. In the initial version of the method, the trench width and mesa width were comparable, giving total overall reductions of ~1/2.…”

Section: Description Of Cantilever Epitaxial Growth Of Ganmentioning

confidence: 99%

Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

Goetz¹,

Imler²,

Kim³

et al. 2004

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Measuring the absolute quantum efficiency of luminescent materials

Cited by 123 publications

References 14 publications

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

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

Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

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