An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

Abstract

Many light emitting diode (LED) phosphors have overlapping emission and absorption bands, such as Ce 3+ -doped garnets and Eu 2+ -doped silicates, nitrides, and oxynitrides. These overlapping bands inevitably lead to self-absorption effects through either nonradiative energy transfer mediated via electron-electron correlation process or actual emission and radiative energy transfer which involves emission and absorption of a photon due to spectral overlap. The first process has been often discussed in the literature. The second process has been investigated in this work through a semi-quantitative formalism. Spectral shift, changes in emission peak shape, photoluminescent conversion efficiency, and phosphor characterization are discussed in light of self-absorption. The simulated results are compared to experimental data and shown to correlate well with observed data.

Gb/s Visible Light Communications With Colloidal Quantum Dot Color Converters

“…This cycle of self-absorption/emission can repeat itself as the emitted photons interact with the CQDs. While a full quantitative study of the problem requires a numerical analysis, we can get useful insights into the process with a simplified approach [25]. For this, we make a number of assumptions as explained in [25]: the optical path length of all photons is equivalent and we consider exactly one self-absorption and re-emission cycle.…”

Structure and white LED properties of Ce-doped YAG-Al2O3eutectics grown by the micro-pulling-down method

“…The position of the emission peaks almost kept the same with increasing thickness of eutectic samples. The intensity of greenish yellow light became stronger gradually as the thickness of the eutectics increased from 0.30 to 0.72 mm, and then decreased with further increase of the thickness of the eutectics due to the reabsorption of the emitted light within the eutectics over a long path length along with a reduction in the emission spectra intensity [32,33]. Based on the SPDs, chromaticity coordinates for the Ce:YAG-Al 2 O 3 eutectics with different Ce 3+ doping concentration are plotted on the CIE-1931 chromaticity diagram [34], as shown in Fig.…”

Flexible but Mechanically Robust Hazy Quantum Dot/Glass Fiber Reinforced Film for Efficiently Luminescent Surface Light Source

“…[ 28,29 ] Even when QDs are uniformly dispersed in polymer binders with high concentration, redshifts of the PL spectra due to reabsorption between QDs and instabilities of QDs such as ligand detachment or chemical degradation remain as challenging problems. [ 30,31 ]…”