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 ²F_5/2→²F_7/2 was recorded at 1039 nm, as a result of efficient energy transfer from Bi³⁺ to Yb³⁺, ions. The phosphors with chemical composition as Y_0.96VO₄: Bi_0.03³⁺, Yb_0.01³⁺ and Y_0.87VO₄: Bi_0.03³⁺,Yb_0.1³⁺ 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.