Nanosheet-based hierarchical ZnO structure decorated with TiO2 particles for enhanced performance in dye-sensitized solar cell

Abstract

A hierarchical ZnO structure assembled by nanosheets was prepared through a low temperature chemical bath deposition and a growing-melting mechanism was proposed to elucidate the shape evolution. Afterwards, a poly (vinylpyrrolidone) (PVP) assisted hydrothermal method was adopted to decorate TiO 2 particles onto the ZnO structure. When used in dye-sensitized solar cells, the device employing the hybrid ZnO/TiO 2 photoanode exhibited improved short-circuit current density (J sc ), open-circuit voltage (V oc ) and filling factor (FF), which resulted in a higher power conversion efficiency (PCE) of 3.60% in comparison to 1.96% from the pure ZnO cell. Based on the investigation of UV-vis absorption and diffuse-reflection spectra, Mott-Schottky analysis, electronic impedance spectra (EIS) and incident monochromatic photo-to-electron conversion efficiency (IPCE), the effect of TiO 2 modification on the photovoltage performances of the ZnO sheet-based hierarchical structures was studied in detail.

CdS Nanoflake Arrays for Highly Efficient Light Trapping

“…Based on the above consideration, 2D nanoflake arrays (NFAs) seem to be promising candidates. Although some nanosheets (e.g., ZnO or TiO 2 ) have been integrated into solar cells, they have not met the above requests totally, due to either small size or random orientation …”

Two dimensional graphitic-phase C3N4 as multifunctional protecting layer for enhanced short-circuit photocurrent in ZnO based dye-sensitized solar cells

“…As indicated in previous literature, the low FF mainly results from the increased series resistance of the cell [15]. Considering the g-C 3 N 4 was wrapped on each ZnO nanoparticle, the additional coating layer inevitably increases the series resistance of photoanode.…”

“…The agglomerations on the ZnO surface not only result in low electron injection efficiency but also trigger massive charge recombination opportunities [11][12][13]. Therefore, surface modification with protecting layers such as SiO 2 Al 2 O 3 or TiO 2 were widely adopted to enhance the stability of ZnO and suppress the charge recombination [14][15][16][17]. In these researches, the additional coating layers function as physical passivating layer to minimize the direct contact between ZnO and the dye molecules, which could significantly improve the fill factor (FF) and open circuit voltage (V oc ) of the devices.…”

Anatase TiO2 hierarchical structures composed of ultra-thin nano-sheets exposing high percentage {001} facets and their application in quantum-dot sensitized solar cells

“…As it is displayed in the high magnification TEM image (Fig. 1 c), the rod-like patterns are related to the vertically allied nano-sheets observed from the side position (as indicated in the inset) [52], revealing the ultra-thin nano-sheets are approximately 20-30 nm in thickness. The HRTEM images in Fig.…”