Effective wavelength conversion from near-UV to red for photovoltaics: Potential of transparent YVO₄:Bi³⁺,Eu³⁺ nanophosphor film

The authors prepared a near-UV to red wavelength conversion thick film containing 38.8 wt% of YVO₄:Bi³⁺,Eu³⁺ nanoparticles of 10.8 ± 1.6 nm in size. This nanoparticle film shows a high transparency in the visible region, e.g., the transmittance at 619 nm is ∼ 96% irrespective of the film thickness. The photoluminescence intensity at 619 nm corresponding to the f-f transition of Eu³⁺ for this nanoparticle film increases with increasing the film thickness up to 400 μm, whereas that of the film containing micron-sized particles reaches the maximum at the film thickness of ∼ 40 μm. On the other hand, YVO ₄:Bi³⁺,Eu³⁺ nanoparticles have a sufficient photostability for practical use over 15 years outside, as confirmed by the light fastness test. These results suggest that the transparent film of YVO ₄:Bi³⁺,Eu³⁺ nanoparticles are potentially applicable to the spectral convertor for photovoltaic cells from the aspects of low light-scattering loss and high photostability.