Highly efficient rare-earth free vanadate phosphors for WLEDs

Abstract

Yellow-green emitting phosphors of vanadate Ca5Mg4(VO4)6 (CMV) doped with different concentrations of Ta5+ ions were synthesized by a solid-state reaction method. The formation of single-phased compounds with garnet structure was...

Multifaceted insight into the cation-disordered self-activated luminescence of Zn3V2O8 compositions for lighting and pigment applications

“…The PLE spectra from 200 to 500 nm with a maximum at 350 nm consisting of two excitation bands at 318 nm (Ex 1 ) and 354 nm (Ex 2 ) correspond to spin-allowed transitions from the 1 A 1 ground state to the 1 T 2 and 1 T 1 excited states of VO 4 3− , respectively. 58–60 The special luminescence properties of the Zn 3 V 2 O 8 phosphor are also attributed to exciton's diffusion inherent in this phosphor. 27 The Zn-3d and O-2p orbitals are hybridized to construct the valence band by favouring the mobility of photo-excited holes in the valence band, which is schematically shown in Fig.…”

“…Generally, the emission in vanadate compounds originates from the charge transfer between the 3d orbital of V 5+ metal and the 2p orbital of O 2− ligands. 58 The broadband emission spectra of the ZVO host monitored at 350 nm displayed a maximum at 550 nm by covering the entire visible region from 400 to 800 nm. The PL spectra contain Gaussian-fitted emission bands at 532 and 583 nm and are assigned to the 3 T 2 → 1 A 1 and 3 T 1 → 1 A 1 transitions in VO 4 3− , respectively.…”

“…Liu et al reported that the emission decay time of the Ca 5 Mg 4 (VO 4 ) 6 phosphor increased after the incorporation of Ta 5+ ions. 58 Nakajima et al investigated the color properties of AVO 3 (A: Li, Na, K, Rb, and Cs), M 2 V 2 O 7 (M: Mg, Ca, Sr, Ba, and Zn), and M 3 V 2 O 8 (M: Mg, Ca, Sr, Ba, and Zn). According to him, the strong V–V interaction owing to the reduced distance between V 5+ ions may increase the fluorescence lifetime of the optical VO 4 3− centers.…”

Engineering linkers to regulate solid-state emission of spirodifluorene-based conjugated porous polymers for white light-emitting devices

“…However, there are some pro-blems in the preparation of LED devices, such as film-related difficulties, process complexity, and the need for precious metals or rare earth elements that make it impossible to produce sustainably. [9][10][11][12][13][14] For organic materials, 15,16 the luminous efficiency for small-molecule organic materials is greatly reduced due to the inherent aggregation-caused quenching effect. 17 The desired luminescence effect for traditional polymer materials requires chemical doping to achieve different ratios of organic fluorescent groups, which often needs a lot of time for pre-designing the structure and regulating the proportion of the dopant, causing a high cost of time.…”