Synthesis and electrochemical performance of α-Al2O3 and M-Al2O4 spinel nanocomposites in hybrid quantum dot-sensitized solar cells
Sawsan A. Mahmoud, Moustafa E. Elsisi, Asmaa F. Mansour
Abstract
Abstract The aim of this study is to describe the performance of the aluminum oxide nanoparticle and metal aluminate spinel nanoparticle as photo-anodes in quantum dot photovoltaic. By using a sol–gel auto combustion method, Al 2 O 3 NPs, CoAl 2 O 4 , CuAl 2 O 4 , NiAl 2 O 4 , and ZnAl 2 O 4 were successfully synthesized. The formation of Al 2 O 3 NPs and MAl 2 O 4 (M=Co, Cu, Ni, Zn) nanocomposite was confirmed by using several characteristics such as XRD, UV–Vis, FTIR, FE-SEM, and EDX spectra. The XRD shows that the CoAl 2 O 4 has a smaller crystallite size (12.37 nm) than CuAl 2 O 4, NiAl 2 O 4 , and ZnAl 2 O 4 . The formation of a single-phase spinel structure of the calcined samples at 1100 °C was confirmed by FTIR. Our studies showed that the pure Al 2 O 3 NP s have a lower energy gap (1.37 eV) than synthesized MAl 2 O 4 under UV–Vis irradiation. Due to the well separation between the light-generated electrons and the formed holes, the cell containing ZnAl 2 O 4 nanocomposite with CdS QDs has the highest efficiency of 8.22% and the current density of 22.86 mA cm −2 , while the cell based on NiAl 2 O 4 as a photoelectrode, six cycles of CdS/ZnS QDs, and P-rGO as a counter electrode achieved the best (PCE) power conversion efficiency of 15.14% and the current density of 28.22 mA cm −2 . Electrochemical impedance spectroscopy shows that ZnAl 2 O 4 and NiAl 2 O 4 nanocomposites have the highest life times of the photogenerated electrons ( τ n ) of 11*10 −2 and 96*10 −3 ms , respectively, and the lowest diffusion rates (K eff ) of 9.09 and 10.42 ms −1 , respectively.