Fabrication of dual excitation dual emission phosphor with plasmonic enhancement of fluorescence for simultaneous conversion of solar UV and IR to visible radiation
A dual excitation, dual emission phosphor has been fabricated by simultaneous doping of lanthanide ions Er3+, Yb3+, Eu3+ in a highly efficient host YVO4. YVO4 doped with Er3+, Yb3+, Eu3+ showed dual excitation i.e., simultaneously excitable by UV and IR radiation and dual emission i.e., bright red fluorescence under UV excitation and intense green under IR excitation. Red DC fluorescence arises due to 5D0–7FJ transitions of Eu3+. UC emission spectra indicate that Yb3+ not only sensitizes Er3+ to emit predominantly in the green but also Eu3+ to produce a signature red emission. A direct assembly of Ag nanoparticles (NPs) and YVO4:Er3+, Yb3+, Eu3+ on a suitable substrate showed enhancement of fluorescence of Eu3+ red emission under UV excitation. Such studies indicate that a two dimensional conformal transparent layer of a Ag NP–phosphor combined on a silicon solar cell may be used as a DC and UC solar spectrum converter from UV/IR to the visible region where the spectral response of Si is high.