Electrospun ZnO nanofibers as a photoelectrode in dye-sensitized solar cells

A nanoparticle-based DSSC shows limited efficiency levels due to its disordered geometrical structure and interfacial interference during electron transport, whereas the use of nanofibers in a DSSC can increase the electron mobility at the interfacial area of the materials due to the reduced recombination of electrons before reaching the collecting electrode. In this study, we describe the fabrication and characteristics of a ZnO nanofiber electrode for DSSC. From the results of a thermogravimetric analysis, a stepped heat treatment was developed for the calcinations of the ZnO electrodes. The ZnO electrode morphology and crystalline structure were confirmed by scanning electron microscopy and the X-ray diffraction patterns, respectively. The DSSC with the ZnO nanofiber photoelectrode (wire shaped) created by electrospinning showed an enhanced short-circuit current density (37% enhancement) compared to that of a ZnO sphere particle-shaped photoelectrode under irradiation of AM 1.5 simulated sunlight (100 mW/cm²). Moreover, we have investigated the origin of the improved performance through electrochemical impedance spectroscopic (EIS) and open-circuit voltage-decay (OCVD) measurements.