The internal luminescence quantum efficiency and color properties of AVO3 (A: Li, Na, K, Rb, and Cs), M2V2O7 (M: Mg, Ca, Sr, Ba, and Zn), and M3V2O8 (M: Mg, Ca, Sr, Ba, and Zn) have been investigated. These vanadate phosphors exhibited broadband emission from 400 nm to over 800 nm due to the one-electron charge transfer transition in the VO4 tetrahedra, and the color of the luminescent materials ranged from green to yellow-orange via white, corresponding to 0.277 < x < 0.494 and 0.389 < y < 0.488 on the CIE chromaticity diagram. We found that the luminescence quantum efficiency of the vanadate phosphors with VO4 tetrahedra was strongly enhanced by the strong interaction between V ions and the weak interaction between V and A(M) ions in the crystal structures. We hypothesize that the long exciton diffusion lifetime induced by these structural features enhanced luminescence, leading to high quantum efficiency.

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White-light-emitting materials have attracted considerable attention because of their applications, such as large-surface emitting devices. Inorganic phosphor films are expected to be applied to these devices because of good chemical stability; however, a substantial reduction of fabrication temperature is required for future industrial uses such as lighting materials fabricated onto flexible organic substrates. Here we show the optical properties of white-light-emitting metavanadate phosphors, AVO3 (A: K, Rb and Cs), and we report a new direct fabrication process for RbVO3 films onto flexible polyethylene terephthalate (PET) substrates by means of a vacuum ultraviolet irradiation using an excimer lamp. In addition, the (Ca,Sr,Pr)TiO3/a-Al2O3/RbVO3/PET heterostructure prepared by an excimer-laser-assisted metal-organic deposition process has demonstrated the possibility of colour modification for RbVO3 films on PET. Our findings suggest new possibilities for further development of large-surface emitting lighting devices.

The fabrication of thin oxide films at low temperatures using simple processes has been a significant challenge associated with expanding the potential applications of these materials. Recent developments have demonstrated that the photo-assisted chemical solution deposition (PACSD) process offers a promising means of solving these difficulties, allowing high volume, on-demand production of variable sample sizes using an advantageous wet process. A better understanding of the crystal growth phenomena associated with this process, however, is required to enable various oxide thin films to be prepared using this new concept. Under pulsed ultraviolet (UV) laser irradiation, crystal growth has been confirmed to proceed by near-instantaneous photothermal heating and photochemical effects at the reaction interface. Vacuum UV lamp irradiation is also a useful means of generating oxide nuclei, since it results in effective chemical bond cleavage and simultaneously produces reactive oxidant (O3/O((1)D)) species. In this review, the nucleation and growth mechanisms which occur during the PACSD process are introduced and discussed and we examine the future possible applications of this process.