Structural parameters of hydrothermally synthesized ZnO nanostructure and their based solar cells

Abstract

ZnO nanostructure (NS) were prepared via hydrothermal route at various times of heat treatment. The structural properties of ZnO (NS) were reported using X-ray diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HR-TEM). The obtained XRD peaks matched with the standard hexagonal wurtzite crystal structure of ZnO ((ICSD) No. 067454)). Additionally, no noticed peaks corresponded to any phase. The crystal structure, lattice defects and the stress–strain parameters were examined using different models (Size–strain plot method (SPP) Williamson–Hall (W–H) and Halder–Wagner (H–W)), which showed a variation by changing the heating (aging) time (HT). It was found that crystal structure, lattice defects and the stress–strain parameters changed with changing HT. The obtained HR-TEM of the ZnO NS indicated good crystalline structure, spherical and uniform shape. The optical properties of the obtained ZnO NS as a function of HT were described using the spectroscopies: UV–Vis and photoluminescence (PL). The UV–Vis results exhibited a red shift for the absorption band edges, where the estimated optical energy gap (Eg) slightly decreased and shifted to the lower energy region with increasing of HT. The PL emission spectra of the ZnO NS decomposed into two sections ranged from visible to Near-Ultraviolet (NUV). The obtained optical properties are in full agreement with the variation of structural properties obtained using the different XRD models and HR-TEM results. The synthesized particles were used as photoanode in DSSCs sensitized by different organic dyes (Eosin B, Rhodamine B, and Eosin Y). A variation of the overall cell efficiency was observed by changing HT. the sensitizer Eosin Y showed the best efficiency over the other organic dyes with light to electric efficiency of 1%.