Coupling effects of Au-decorated core-shell β-NaYF4:Er/Yb@SiO2 microprisms in dye-sensitized solar cells: plasmon resonance versus upconversion

We synthesized highly uniform Au-decorated core-shell β-NaYF4:Er/Yb@SiO2 microprisms and investigated its coupling effects on the performance of dye-sensitized solar cells (DSCs). The incorporation of upconversion phosphors (UCPs) and localized surface plasmon resonance (LSPR) arising from Au nanoparticles (AuNPs) was beneficial to achieve a higher photocurrent and power conversion efficiency of the devices. Furthermore, the contribution and interaction between upconversion and LSPR on the performance of DSCs were identified by UV-vis spectroscopy, upconversion fluorescence spectroscopy, and J-V characterization under different simulated illuminations. The presence of AuNPs increased the optical absorption of dye molecules in the visible region, but decreased the emission of UCPs. Thorough analysis showed that the energy of upconversion emission was transferred to the upconversion induced LSPR of AuNPs, that resulted from the incorporation between the SPR band of AuNPs and a matched emission bands of UCPs. These results validated the advantages of incorporation between upconversion and LSPR for DSC applications and revealed the underlying enhancement mechanism.