Sol-electrophoretic deposition of TiO2 nanoparticle/nanorod array for photoanode of dye-sensitized solar cell

Abstract

In this investigation, we represent the role of titania (TiO2) nanorod arrays (NRAs) in enhancing the efficiency of dye-sensitized solar cells (DSSCs). Synthesizing TiO2 NRAs via sol-electrophoretic deposition (EPD) by utilizing anodized aluminum oxide (AAO) nanochannel patterns results in one-dimensional morphology of NRAs, confirmed by field emission scanning electron microscope (FESEM) images. Furthermore, a thorough study is performed to clarify every step of NRAs formation from AAO role to reach the best number of deposited layers and a stable morphology. In this way, energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and current-time (J-t) graphs help clarifying this section. To explicate the role of NRAs in boosting the DSSC efficiency, three layers of deposited TiO2 nanoparticles (NPs) using TiO2 sol by the EPD method is compared with a similar sample but consisting of NRAs (nanorod-nanoparticle, NR-NP). Current-voltage (J-V) and electrochemical impedance spectroscopy (EIS) analyses are employed and photovoltaic parameters show NRAs could increase the efficiency of DSSC more than two times from 1.49% (for NP sample) to 3.37% (for NR-NP sample). In addition, EIS results reveal a great drop in TiO2 resistance from 232.2 Ω to 45.13 Ω, indicating the efficient role of NRAs addition in improving the charge transport.