The Effect of Different Concentrations of Molybdenum Trioxide in Electrolyte for Dye-Sensitized Solar Cells (DSSCs): Performance Enhancement of DSSCs

Dye-sensitized solar cells (DSSCs)' photovoltaic conversion efficiency is decreased by recombination reactions at the photo anode/electrolyte interface. Herein, a new molybdenum trioxide ( $\text{MoO}_{3}$ ) function is used as a treatment agent for electrolytes. $\text{MoO}_{3}$ added to the electrolyte precludes recombination of electrons with triiodide ( $I_{3}^{-}$ ) ions at photoanodes/electrolyte interface by adsorbing anions (triiodide/iodide) from the electrolyte on its surface. After $\text{MoO}_{3}$ treatment, the electrochemical properties of the electrolytes do not change significantly but the power conversion efficiency of the DSSCs have clearly improved from 6.31% to 7.47%, owing primarily to higher open-circuit voltages. Different weight percentages of $\text{MoO}_{3}$ were added into the electrolyte: 0, 0.1, 0.2, 0.3, 0.4, and 0.5 wt%. $\text{MoO}_{3}$ are injected directly into electrolytes, good shake, and followed by centrifugation to obtain clear electrolytes. Clear electrolytes were measured by electrochemical impedance spectroscopy, Mott–Schottky, current density–voltage, and open circuit voltage decay (OCVD) measurements. This anionic adsorption onto the $\text{MoO}_{3}$ in the electrolyte has been confirmed by the scanning electron microscope, energy-dispersive X-ray, and Fourier-transform infrared spectroscopy of molybdenum dioxide particles before and after injected into the electrolyte. UV-Vis measurements were carried out before and after centrifugation for electrolytes.