ZnO NANOPOROUS DISK–TiO₂ NANOPARTICLE HYBRID FILM ELECTRODE FOR DYE-SENSITIZED SOLAR CELLS

Abstract

Micron-sized ZnO disks with nanosized pores were synthesized by decomposing the solution-grown layered zinc compound ZnCl 2 · [ Zn ( OH ) 2 ] 4 · H 2 O ( ZCOH ) at 500°C. ZnO – TiO 2 hybrid film electrodes were prepared by the doctor-blade method, adding ZnO disk powder to the TiO 2 slurry. The crystallinity, microstructure and optical properties of the ZCOH , ZnO nanoporous disk, and the resulting hybrid films, were investigated. Electrochemical impedance spectroscopy and the photocurrent density–voltage curve were employed to characterize the interfacial electron-transporting properties and photoelectrochemical performance of dye-sensitized solar cells (DSCs) using the ZnO – TiO 2 hybrid electrode. Results indicated that the incorporation of a small amount of ZnO disks into the TiO 2 film (less than 1%) can roughen the surface structure, reduce the film thickness, enhance the light scattering in the visible and infrared bands, and increase the interfacial charge transport rate. Hybrid cells showed efficiency improvements of 145% and 109% with the concentrations of ZnO of 0.5% and 1% in the hybrid film respectively, compared with the traditional TiO 2 cell, with a significant increase in the short-currency density and the fill factor. Although the 2.7% efficiency (J sc = 4.0 mA ° cm -2 ; V oc = 0.74 was not high with the 0.5% ZnO disk incorporated, this work highlighted the potential improvement that novel ZnO nanostructures in hybrid DSCs can achieve.