Fabrication of TiO2 nanoparticle/TiO2 microcone array photoanode for fiber-type dye-sensitized solar cells: Effect of acid concentration on morphology of microcone

Fiber-type dye-sensitized solar cell (FDSSC) is one of the promising energy generating devices for soft electronics, especially due to the great photon-to-electricity conversion ability even under weak deem light. High dye adsorption, great light utilization, efficient charger-transfer routes and excellent flexibility are required for the photoanode of FDSSCs. In this study, flexible Ti wires are etched using different concentrations of H2SO4 electrolytes in anodization process to form TiO2 microcone array (TMC) as the photoanode of FDSSCs at the first time. Growth mechanism of TMC in different concentrations of H2SO4 electrolytes is proposed to more clearly explain the acid concentration effects. The FDSSC with the TMC photoanode prepared using 4 MH2SO4 electrolyte shows the highest photon-to-electricity conversion efficiency (h) of 2.11%, due to the formation of well-distributed TMC to provide one-dimensional charge-transfer paths and induce effective light scattering. The TiO2 nanoparticle (TNP) is deposited on TMC using dip-coating technique. The h is enhanced to 3.70% for the FDSSC with the optimized TNP thickness, which is able to provide sufficient surface area for dye adsorption and prevent the thickness from exceeding charge diffusion length. Electrochemical impedance spectroscopy is used to analyze the charge-transfer resistance of FDSSCs with the fancy TNP/TMC photoanodes. (c) 2019 Elsevier Ltd. All rights reserved.