Broad band down conversion from ultra violet light to near infrared emission in YVO4:Bi3+, Yb3+ as spectral conversion phosphor for c-Si solar cells

Vanadate based down conversion phosphors have been synthesized by a novel co-precipitation technique. The effect of pH on crystal structure, particle size, morphology and luminescence properties were investigated by XRD, SEM-EDAX, FT-IR and PL measurements. As different from other reports (blue, green emission) the produced phosphors have shown greenish–yellow emission, owing to their fine particle size. A broad band excitation (280–370 nm), ascribed to 1S0→3P1 and an intense greenish–yellow band emission (410–700 nm) attributed to 3P1→1S0 transition of Bi3+ were observed. A strong greenish–yellow emission was measured with 3 mol. % of Bi3+ ions, as an optimum dopant concentration. The characteristic NIR emission of Yb3+, owing to 2F5/2→2F7/2 was recorded at 1039 nm, as a result of efficient energy transfer from Bi3+ to Yb3+, ions. The phosphors with chemical composition as Y0.96VO4: Bi0.033+, Yb0.013+ and Y0.87VO4: Bi0.033+,Yb0.13+ are suggested to be the novel candidates for the efficient down conversion of broad band ultra violet (UV) light into visible/near infrared (NIR) emission, as DC layers on c-Si solar cells for better harvesting the solar spectrum via spectral matching phenomena.