Surface plasmon resonance enhanced multi-shell-modified upconversion NaYF4:Yb3+, Er3+@SiO2@Au@TiO2 crystallites for dye-sensitized solar cells

Both upconversion of near-infrared light and surface plasmon resonance (SPR) of nobel metal nano particles (NPs) show potential application in dye-sensitized solar cells(DSSCs). For the first time, the novel multi-shell-coated and Au-NPs decorated hexagonal submicron beta-NaYF4:Yb3+, Er3+(NFYE)@SiO2@Au@TiO2(NSAT) prisms were prepared and incorporated into the photoanodes of DSSCs. The influences of different coating layers and decorated Au-NPs on the upconversion of NFYE and the performance of DSSCs were comparatively investigated. Studies indicated that the coated multi-shells have great influences on the upconversion and the properties of DSSCs. The Au-NPs can remarkably enhance the intensity of upconversion luminous emission and thus the short-circuit current density (J(sc)) and photoelectron conversion efficiency (eta) of the DSSCs. The TiO2 shell is beneficial for absorbing more dye and lowering the interface transport resistance. The optimal J(sc) and eta obtained in a typical DSSC containing NSAT are 18.62 mA/cm(2) and 7.79%, respectively, corresponding 38.2% and 28.1% higher than that of the DSSC with a pure TiO2 photoanode. This significant improvement can be mainly attributed to the enhanced upconversion emission of the NSAT prisms arising from the SPR effect of the embeded Au-NPs and to the possible enhanced scattering from the submicron prisms. (C) 2016 Elsevier B.V. All rights reserved.