Dataset Information

New strategy for designing orangish-red-emitting phosphor via oxygen-vacancy-induced electronic localization.

ABSTRACT: Phosphor-converted white-light-emitting diodes (pc-WLED) have been extensively employed as solid-state lighting sources, which have a very important role in people's daily lives. However, due to the scarcity of the red component, it is difficult to realize warm white light efficiently. Hence, red-emitting phosphors are urgently required for improving the illumination quality. In this work, we develop a novel orangish-red La4GeO8:Bi3+ phosphor, the emission peak of which is located at 600 nm under near-ultraviolet (n-UV) light excitation. The full width at half maximum (fwhm) is 103 nm, the internal quantum efficiency (IQE) exceeds 88%, and the external quantum efficiency (EQE) is 69%. According to Rietveld refinement analysis and density functional theory (DFT) calculations, Bi3+ ions randomly occupy all La sites in orthorhombic La4GeO8. Importantly, the oxygen-vacancy-induced electronic localization around the Bi3+ ions is the main reason for the highly efficient orangish-red luminescence. These results provide a new perspective and insight from the local electron structure for designing inorganic phosphor materials that realize the unique luminescence performance of Bi3+ ions.

SUBMITTER: Wei Y

PROVIDER: S-EPMC6351663 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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New strategy for designing orangish-red-emitting phosphor via oxygen-vacancy-induced electronic localization.

Wei Yi Y Xing Gongcheng G Liu Kang K Li Guogang G Dang Peipei P Liang Sisi S Liu Min M Cheng Ziyong Z Jin Dayong D Lin Jun J

Light, science & applications 20190130

Phosphor-converted white-light-emitting diodes (pc-WLED) have been extensively employed as solid-state lighting sources, which have a very important role in people's daily lives. However, due to the scarcity of the red component, it is difficult to realize warm white light efficiently. Hence, red-emitting phosphors are urgently required for improving the illumination quality. In this work, we develop a novel orangish-red La4GeO8:Bi3+ phosphor, the emission peak o ...[more]

PMID: 30728955

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Project description:The catalytic performance with high conversion and high selectivity of Ti-based oxide catalysts have been widely investigated. Besides, stability, which is an essential parameter in the industrial process, lacked fundamental understanding. In this work, we combined computational and experimental techniques to provide insight into the deactivation of P25 and TS-1 Ti-based oxide catalysts during the methyl oleate (MO) epoxidation. The considered deactivation mechanisms are fouling and surface oxygen vacancy (OV). The fouling causes temporary catalyst deactivation through active site blockage but can be removed via calcination in air at high temperature. However, in this work, the OV formation plays an important role in the overall performance of the spent catalyst as the deactivated catalyst after regeneration, cannot be restored to the initial activity. Also, the effects of OV in spent catalysts caused (i) the formation of more Ti3+ species on the surface as evident by XPS and Bader charge analysis, (ii) the activity modification of the active region on the catalyst surface as the reduction in energy gap (Eg) occurred from the formation of the interstates observed in the density of states profiles of spent catalyst modeled by the O-vacant P25 and TS-1 models. This reduction in Eg affects directly the strength of Ti-OOH active site and MO bonding, in which high binding energy contributes to a low conversion because the MO needed an O atom from Ti-OOH site to form the methyl-9,10-epoxy stearate. Hence, the deactivation of the Ti-based oxide catalysts is caused not only by the insoluble by-products blocking the active region but also mainly from the OV. Note that the design of reactive and stable Ti-based oxide catalysts for MO epoxidation needed strategies to prevent OV formation that permanently deactivated the active region. Thus, the interrelation and magnitude between fouling and OV formation on catalyst deactivation will be investigated in future works.

Dataset Information

New strategy for designing orangish-red-emitting phosphor via oxygen-vacancy-induced electronic localization.

Publications

New strategy for designing orangish-red-emitting phosphor via oxygen-vacancy-induced electronic localization.

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