Microsphere Light-Scattering Layer Assembled by ZnO Nanosheets for the Construction of High Efficiency (>5%) Quantum Dots Sensitized Solar Cells

Abstract

This work reported on a bilayer photoelectrode constructed by ZnO nanoparticle (NP) film and ZnO microsphere (MS) scattering layer for CdS/CdSe quantum dot cosensitized solar cells (QDSCs) with a power conversion efficiency (PCE) of greater than 5%. We controlled the growth orientations of ZnO crystals to form nanosheets, which attached together and assembled into MS due to the high surface energy of the nanosheets. MSs were used as a top layer to effectively increase the light diffuse reflection and harvesting to enhance photogenerated current. In comparison with ZnO NPs photoelectrode, the short circuit current density (Jsc) of ZnO NPs/MSs photoelectrode increased from 10.3 mA/cm2 to 16.0 mA/cm2, which was an enhancement of 55%. To further increase the fill factor and PCE of QDSCs, ZnO NPs/MSs was treated in the solution of H3BO3 and (NH4)2TiF6 to form a barrier surface layer, which suppressed the charge recombination and prolonged electron lifetime. As a result, the solar cell displayed Jsc of 17.13 mA...