Synthesis and characterization of Er³⁺-Yb³⁺ doped ZnO upconversion nanoparticles for solar cell application

Erbium (Er³⁺) and ytterbium (Yb³⁺) co-doped ZnO upconversion (UC) nanoparticles based phosphors are synthesized by solution-combustion method. These UC phosphors are shown a strong UC emissions at red, green and blue wavelengths with the excitation of 980 nm diode laser source. To understand the influence of ZnO:Er³⁺-Yb³⁺ UC based nanoparticles on the performance of dye sensitized solar cells (DSSCs), the UC nanoparticles are incorporated into scattering layer of titanium dioxide films in the form of composite photoanode. The power conversion efficiency (PCE) of the DSSCs is increased from 8.34 to 8.72% after incorporation of ZnO:Er³⁺-Yb³⁺ upconverting nanoparticles. This enhancement in the PCE is due to increase in the short circuit current density (J_SC) of 18.66 mA cm⁻². The enhancement in the J_sc is due to the infrared light harvesting from infrared into the visible region, while the PCE of reference DSSC (without up conversion layer) is obtained 8.34% with the J_SC of 17.89 mA cm⁻².