Negative Thermal Quenching of Photoluminescence: An Evaluation from the Macroscopic Viewpoint

Abstract

Negative thermal quenching (NTQ) denotes that the integral emission spectral intensity of a given phosphor increases continuously with increasing temperature up to a certain elevated temperature. NTQ has been the subject of intensive investigations in recent years, and a large number of phosphors are reported to have exhibited NTQ. In this paper, a collection of results in the archival literature about NTQ of specific phosphors is discussed from a macroscopic viewpoint, focusing on the following three aspects: (1) Could the NTQ of a given phosphor be reproducible? (2) Could the associated data for a given phosphor exhibiting NTQ be in line with the law of the conservation of energy? (3) Could the NTQ of a given phosphor be demonstrated in a prototype WLED device? By analyzing typical cases based on common sense, we hope to increase awareness of the issues with papers reporting the NTQ of specific phosphors based on spectral intensity, along with the importance of maintaining stable and consistent measurement conditions in temperature-dependent spectral intensity measurement, which is a prerequisite for the validity of the measurement results.

Enhanced VIS-NIR emission of Re4+ doped Cs2ZrCl6 for optical thermometry and near-infrared illumination applications

“…Therefore, the strong electron–phonon coupling effect on the temperature-sensitive spectral characteristics deserves more attention. 35…”

“…Therefore, the strong electron-phonon coupling effect on the temperature-sensitive spectral characteristics deserves more attention. 35 Fig. 4(e) depicts the trend of PL intensity and full width at half maximum (FWHM) with temperature variation at different excitation wavelengths.…”