Optical properties and dye-sensitized solar cell applications of ZnO nanostructures prepared by microwave combustion synthesis.

In the present study, ZnO nanoparticles (ZNPs) and nanoflakes (ZNFs) were prepared by conventional combustion method and microwave combustion method, respectively. The structural phase and morphology were investigated by using X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM). The crystallite size was calculated using Scherrer formula, and it lies in the range of 20-21 nm for ZNFs and 23-28 nm for ZNPs. The elemental analysis was investigated by energy dispersive X-ray analysis (EDX). Also, absorbance and emission spectra were measured by using diffuse reflectance (DRS) and photoluminescence (PL) studies. The band gap was measured using Kubelka-Munk model and it shows 3.47 eV for ZNFs and 3.26 eV for ZNPs. A fill factor (FF) of 0.57, short-circuit current (J(sc)) of 8.02 mA/cm2, open-circuit voltage (V(oc)) of 0.70 V and an overall light to electricity conversion efficiency (eta) of 1.62% were obtained from the dye-sensitized solar cell (DSSCs) based on ZNFs.