Enhanced efficiency of DSSC through AC-electrophoretic hybridization of TiO2 nanoparticle and nanotube

Abstract

In this study, an efficient hybrid photoanode consisting of freestanding TiO2 nanotube (TNT) membranes and TiO2 nanoparticles (TNPs) was fabricated by high-frequency AC-electrophoresis deposition (TNT-TNP-EPD). The photovoltaic performance, transient properties and electron transport resistance of TNT-TNP-EPD photoanode were analyzed by photocurrent density-voltage (I–V) curve, open circuit voltage decay (OCVD) measurements and electrochemical impedance spectra (EIS). The power conversion efficiency (PCE) of dye-sensitized solar cell (DSSC) fabricated by bare TNT (TNT-B) was significantly improved up to 95% by AC-EPD introducing the TiO2 nanoparticles into the photoanode. The efficiency enhancement is due to produce the very uniform film with a high active surface area which is in turn due to the very regular arrangement of deposited particles by modulated high-frequency AC-EPD. This procedure was compared with doctor blade hybridization (TNT-TNP-DB photoanode) and TiCl4 sol treatment (TNT-TiCl4 photoanode) methods The TNT-TNP-EPD photoanode shows higher PCE than the others. Moreover, the EIS results show that TNT-TNP-EPD has better electron transport than other ones; 31.65 vs. 44.69, 56.86 and 67.34Ω for TNT-TNP-DB, TNT-TiCl4, and TNT-B, respectively. However, the recombination rate of TNT-TNP-EPD is higher than TNT-B and TNT-TiCl4 which can be attributed to the increase of grain boundaries with introducing TNP to the TNT arrays. Nonetheless, the recombination rate of TNT-TNP-EPD is lower than TNT-TNP-DB due to greater uniformity of the nanoparticles in AC-EPD.