Time-Optimized Hydrothermal Synthesis of Nano-WO 3 for Application as Counter Electrode in Dye-Sensitized Solar Cell

Developing a non-platinum (Pt) counter electrode (CE) in dye-sensitized solar cells (DSSCs) gained widespread consideration in scientific research. The counter electrode substitutes for Pt should exhibit enhanced conductivity and electrocatalytic nature. In the current work, tungsten trioxide (WO 3 ) has been employed as CE in DSSC considering its wide bandgap and n-type property to replace the expensive Pt catalyst for triiodide reduction. Nano-tungsten trioxide (WO 3 ) was synthesized using sodium tungstate dihydrate (Na 2 WO 4 ∙2H 2 O) and sodium chloride (NaCl) in an acidic media by a time-optimized hydrothermal route in an autoclave at 200 °C. Physical characterizations of Nano-WO 3 were investigated using FESEM, EDS, FTIR spectroscopy and XRD. The impedance and Tafel polarization curve studies suggest that WO 3 synthesized after 5 h exhibits lower interfacial charge transfer resistance ( R ct ) and higher exchange current density ( J o ) which confirms better activity of the same compared to others. The DSSC assembled with WO 3 as CE gives a short-circuit current density ( J sc ) of 17.01 mA cm −2 , open-circuit voltage ( V oc ) of 0.69 V and, a power conversion efficiency ( η ) of 5.13%. The results suggest that Nano-WO3 can be considered as a potential candidate to substitute platinum.