Cu modified ZnO nanoflakes: An efficient visible light-driven photocatalyst and a promising photoanode for dye sensitized solar cell (DSSC)

Abstract

Zinc oxide (ZnO) with suitable dopant has been reported as a suitable alternative to commercial TiO2, as an efficient photocatalyst and a promising photoanode for dye-sensitized solar cells (DSSCs) application. In this work, Cu doped ZnO nanoflakes with optimal doping have been fabricated for efficient visible light-driven photocatalysis along with promising application in the DSSC system. ZnO with 1 wt % Cu doping showed a significantly improved photocatalytic performance by a factor of 4.66 and 3.25 times under visible and solar irradiation respectively when compared with pristine ZnO. The advantage of ZnO doping with optimal Cu content lies in the fact that it can facilitate the elevated photon absorption along with reduced charge carrier recombination. Additionally, the DSSCs comprise bare ZnO and metal-based dye shows poor performance in terms of power conversion efficiency (PCE). Profiting from the merits of Cu modified ZnO, which prevent the formation of such Zn2+/dye complex, an increase of 3.56 times in PCE is observed for ZnO with optimal Cu doping (1 wt %). Maximum Jsc of 0.81 mA/cm2 is achieved for the ZnO with 1 wt % Cu compare with the Jsc of 0.26 mA/cm2 for the bare ZnO. Interestingly, optimized Cu modified ZnO shows remarkable photocatalytic and photocurrent stability up to a few repeated cycles. The increased photocatalytic and DSSC performance of Cu doped ZnO is discussed in detail based on its different physicochemical properties. Moreover, an expected mechanism is also proposed to explain the superior performance of Cu modified ZnO at optimal content.