Investigation of the photoanode based on graphene/zinc aluminum mixed metal oxide for dye-sensitized solar cell

In this study, zinc aluminum layered double hydroxide (ZnAl-LDH) with a Zn/Al molar ratio 8/1 was synthesized via a facile urea method, and the mixed metal oxide (MMO) was prepared using the corresponding LDH as a precursor. In order to improve the performance of electron transport layer, we introduced graphene into ZnAl-MMO to prepare new nanocomposites, ZnAl-MMO/graphene, as promising photoanodes for dye-sensitized solar cell (DSSC). The bare ZnAl-MMO and formed ZnAl-MMO/graphene nanocomposites were characterized by X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and UV–vis absorption spectrum, confirming the presence of graphene and the wurtzite type phase of ZnO. A series of DSSC were fabricated by the corresponding nanocomposites and a D205 as dye. The photovoltaic behavior of these cells based on different graphene concentration was further investigated by electrochemical method. It turned out that the introduced graphene facilitated the dye adsorption and light-scattering, which heightened the performance of DSSC. The DSSC based on ZnAl-MMO/0.2 wt.% graphene reached the best power conversion efficiency (PCE) of 0.51%, showing a rise of 25% approximately when compared with plain ZnAl-MMO.