Upconversion 32Nb₂O₅-10La₂O₃-16ZrO₂ glass activated with Er³⁺/Yb³⁺ and dye sensitized solar cell application

Er³⁺/Yb³⁺ codoped niobium pentoxide glasses were fabricated by the aerodynamic levitation (ADL) method with rapid cooling rate. All samples with various doping concentrations showed good upconversion luminescence properties under 980 nm laser excitation. The structure, transmittance spectrum, and luminescence properties of the samples were systemically investigated by XRD, UV-Vis-NIR spectrophotometer, and upconversion spectra. All transparent samples exhibited green and red upconversion emissions centered at 532, 547, and 670 nm. Experimental results showed that the sample codoped with 1 mol% Er³⁺/Yb³⁺ has the strongest upconversion emissions, and the increase of the doped Yb³⁺ concentration results in the increased red emission and reduced green emission. The logI-logP plot of green emission indicated that the green emissions reach the saturation at high pump power excitation, deviating from the low-power regime. After one-photon energy transfer (ET) process, ⁴I_11/2+⁴I_11/2→⁴F_7/2+⁴I_15/2 process between the two neighboring Er³⁺ ions was responsible for the population of the ⁴S_3/2/⁴H_11/2 states. The niobium pentoxide codoped with Er³⁺/Yb³⁺ bulk glasses could be used in the dye sensitized solar cell (DSSC) to improve the efficiency.