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

摘要

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 non-radiative 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.