Evolution of highly efficient rare-earth free Cs(1-: X)RbxVO3 phosphors as a single emitting component for NUV-based white LEDs

E. Pavitra, G. Seeta Rama Raju, L. Krishna Bharat, Jin Young Park, Cheol Hwan Kwak, Jong Won Chung, Young Kyu Han, Yun Suk Huh

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Since the commercialization of white light-emitting diodes (WLEDs) in 1996, they are rapidly replacing conventional lighting sources and have become an essential commodity for day-to-day human life. At present, most of the WLEDs existing in the market are rare-earth based, which are very limited, expensive and often not available due to monopolistic supply conditions. Hence, there is a serious demand for novel rare-earth free phosphors to achieve cost-effective and energy-efficient WLEDs with excellent luminous efficacy for general illumination. Herein we report on highly efficient rare-earth free Cs(1-x)RbxVO3 phosphors as a single emitting compound for near UV-based WLEDs manufactured by the citrate sol-gel method for the first time. Rietveld refinement is performed for the X-ray diffraction patterns of the CsVO3 host and CsVO3:0.25Rb phosphors to reveal their orthorhombic pyroxene structure. The difference in the ionic radii of Rb+ and Cs+ ions led to a more distorted VO4 3- tetrahedron with a broken Td symmetry, which allows spin forbidden transitions for CsVO3:0.25Rb phosphors, resulting in enhanced internal and external quantum efficiencies of 94.7% and 84.5% along with superior luminescence properties compared to the CsVO3 host. When varying the input current from 20 to 200 mA, the fabricated WLED exhibited a good color rendering index of 69.7-81.5 and an extremely high luminous efficacy of 94.8-58.7 lm W-1, which are among the highest values for the same host lattice. These rare-earth free CsVO3:0.25Rb phosphors with a single emitting center may emerge as a new class of advanced inorganic phosphors for near UV-based WLEDs in the lighting industries.

Original languageEnglish
Pages (from-to)12746-12757
Number of pages12
JournalJournal of Materials Chemistry C
Volume6
Issue number46
DOIs
StatePublished - 2018

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