Vanadium oxides (V₂O₅) prepared with different methods for application as counter electrodes in dye-sensitized solar cells (DSCs)

V₂O₅ was synthesized by four different procedures employing thermal decomposition, sol-gel, and hydrothermal methods which were subsequently introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) catalysts for the regeneration of traditional iodide/triiodide (I^-/I₃ ^-) redox couple. The catalytic activities of as-prepared V₂O₅ were significantly affected by the synthetic routes as evidenced by cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization curve. Power conversion efficiency (PCE) of the DSCs employing V₂O₅ CE, fabricated by thermal decomposition method, was observed to be 3.80 % by using citric acid as an additive, while the PCE of the DSCs using V₂O₅ CE prepared by hydrothermal and thermal decomposition methods without additive, as well as by a sol-gel procedure, was determined to be 2.13, 2.08, and 2.04 %, respectively. (orig.)