A NaGdGeO: Tm3+, Dy3+ Phosphor with Anomalous Thermal Quenching for Use in WLEDs

NaGd_1–x–y GeO₄: xTm³⁺, yDy³⁺ phosphors for white light-emitting diodes are synthesized by a high-temperature solid-phase method. By utilizing the energy transfer mechanism, anomalous thermal quenching and adjustable white light have been achieved.

A series of novel NaGdGeO₄: Tm³⁺, Dy³⁺ phosphors are prepared by a facile high-temperature solid-state method. By continuously adjusting the Dy/Tm ion concentrations, the white light emission with adjustable color temperature and color coordinate is achieved excited by the wavelength of 354 nm. The energy transfer mechanism between sensitized ions and activated ions is discussed with the help of fluorescence spectra and decay curve in details. Notably, different from other phosphors based on this host material, these prepared phosphors exhibit typical anomalous thermal quenching. It is very favorable for the devices working at high temperature. And this phenomenon may benefit from the high energy transfer efficiency at higher temperatures. The tunable white light and anomalous thermal quenching indicate that the studied material is a promising solid-state emitting phosphor for the white light-emitting diodes.

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