Highly thermally stable and emission color tunable borate glass for white‐light‐emitting diodes with zero organic resin

Abstract

AbstractWhite‐light‐emitting glass is a kind of potential bireplacement of both phosphors and epoxy resin in high‐power white‐light‐emitting diodes (WLEDs) because of its high thermal conductivity and excellent thermal stability in aspect of luminescence, CIE chromaticity, and transmittance. In this study, a series of tunable white‐light‐emitting strontium borate (SBO) glass SBO:Tb3+,Eu3+ were prepared by conventional melt quenching method, and their luminescence properties were systematically studied through their photoluminescence excitation and emission spectra, decay curves, and quantum efficiency. Intense white light emitting can be achieved by in situ mixing of yellowish green and reddish orange emissions from Tb3+ and Eu3+, respectively, in single glass component SBO, and mixed white emissions can be tuned by Tb3+→Eu3+ energy transfer with the increasing concentration of energy acceptor Eu3+. The quantum efficiency of optimal glass SBO:10%Tb3+,6%Eu3+ was measured as 36.78%. And the excellent thermal stability of this glass can remain its luminescence intensity above 80% at the temperatures below 523 K. Its chromaticity shift is less than 0.01 at the temperature below 548 K, which is far smaller than that of commercial DS‐200 and triple‐color white‐emitting phosphor mixture. Except all above, the transmittance of this glass hardly shows loss after thermal aging at 120°C for 240 hours, which is superior to the only remaining 58.8% transmittance of epoxy resin. The thermal conductivity of this glass is 0.65 W/mK much better than the 0.16 W/mK of epoxy resin. Based on above research results, SBO:Tb3+,Eu3+ glass is considered as a promising candidate for high‐power WLEDs, thus a SBO‐WLED is simply assembled by SBO:10%Tb3+,6%Eu3+ glass and 378 nm LED chip that can present excellent luminescence performance with V=10 V, I=600 mA.