Abstract
The development of high-power white light-emitting diodes demands highly efficient and stable all-inorganic color converters. In this respect, phosphor-glass/ceramic composites show great promise as they could combine the merits of high quantum efficiency of phosphors and high chemical and thermal stabilities of glass/ceramic matrices. However, strong interfacial reaction between phosphors and matrices at high temperature results in quantum efficiency loss of the embedded phosphors, and traditional solutions rely on high-pressure consolidation techniques. Here we report the intrinsic inhibition of interfacial reaction by using silica glass rather than multicomponent glasses as the matrix. The embedment of phosphors is achieved via a pressureless sintering method, rendering these color-tunable phosphor-glass composites not only accessible to three-dimensional printing technique, but also highly efficient (internal quantum efficiency >90.0%), thermally stable at 1200 °C and hydrothermally stable at 200 °C. Our results provide a facile and general strategy for developing all-inorganic functional composites.
Highlights
The development of high-power white light-emitting diodes demands highly efficient and stable all-inorganic color converters
Despite extensive research in developing new phosphors for pc-WLEDs1–3,11, the yellow phosphor YAG:Ce is still the dominant one owing to its suitable excitation and emission spectra, high internal QE (IQE), and superior chemical and thermal stabilities[35]
The crystal structure of YAG:Ce is thermally stable up to 1700 °C36, and its IQE can be well maintained after heat treatment for 3 h at 800 °C in air (Supplementary Fig. 1), but YAG:Ce-glass/ceramic composites sintered at 700 °C for less than 30 min show obvious IQE loss[19,26,27], suggesting that using low-melting materials is not an effective way to inhibit interfacial reaction
Summary
The development of high-power white light-emitting diodes demands highly efficient and stable all-inorganic color converters In this respect, phosphor-glass/ceramic composites show great promise as they could combine the merits of high quantum efficiency of phosphors and high chemical and thermal stabilities of glass/ceramic matrices. High quantum efficiency (QE) of phosphors is seldom retained by these strategies even though they have sacrificed the high chemical and thermal stabilities and the facile synthesis[10] Those reported matrices suffer from certain disadvantages including low visible transparency[17,24,25,26,27], high price[17,18] and heavy metal (for example, Pb and Sb) containment[30,31]. By virtue of pressureless sintering, we realize the freeform fabrication of all-inorganic color converters for the first time by combining with modern 3D printing technology
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