Preparation, electronic structure and photoluminescence properties of RE (RE = Ce, Yb)-activated SrAlSi4N7 phosphors
| Autor: | Rong-Jun Xie, Peter H. L. Notten, Marjo J. H. Stevens, Zhijun Zhang, Zhen-Yong Man, Yu-Fang Shen, Hubertus T. Hintzen, A.C.A. Delsing, Otmar M. ten Kate, Pieter Dorenbos, Jing-Tai Zhao |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: | |
| Zdroj: | Journal of Materials Chemistry C, 1(47), 7856-7865. Royal Society of Chemistry |
| ISSN: | 2050-7534 2050-7526 |
| Popis: | The electronic structure of SrAlSi4N7 was calculated using the CASTEP code and SrAlSi4N7 is an intermediate band gap semiconductor with an indirect energy gap of 3.6 eV. Ce3+ and Yb2+-activated SrAlSi4N7 samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. SrAlSi4N7:Ce3+ shows a broad band emission in the wavelength range of 450–700 nm, originating from the 5d1–4f1 transition of Ce3+. The emission band of Ce3+ shifts to longer wavelength with an increase of Ce3+ concentration due to the increased Stokes shift and reabsorption by Ce3+. SrAlSi4N7:Yb2+ can be excited efficiently over a broad spectral range between 300 and 550 nm, and exhibits a single intense red emission at 600 nm with a full width at half maximum of 95 nm due to the electronic transitions from the excited state of 4f135d to the ground state 4f14 of Yb2+. The low energy of Yb2+ emission in SrAlSi4N7 can be attributed to the large nephelauxetic effect and crystal field splitting due to the coordination of Yb2+ by nitrogen. In addition, Sr1-2xCexLixAlSi4N7 shows higher thermal stability in air than that of Sr1-yYbyAlSi4N7 (0 = x, y = 0.1). A white-light LED can be generated by using single SrAlSi4N7:Ce3+ as the wavelength conversion phosphor combined with a blue LED chip (InGaN). The obtained LED exhibits a luminous efficiency of 74.3 lm W-1 at a corrected color temperature (CCT) up to 6350 K, and the color rendering index (CRI Ra) is around 78. These novel developed yellow-red phosphors have potential applications in spectral conversion materials for white-LEDs. |
| Databáze: | OpenAIRE |
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