Synthesis and electrochemical characterization of pseudocapacitive α-MoO3 thin film as transparent electrode material in optoelectronic and energy storage devices

Highlights: • A template transparent MoO₃ electrode material suitable for photovoltaic and supercapacitor was designed. • Photon charge extraction and transport and ion intercalation of the electrode were investigated. • Some surface properties of the fabricated electrode were also studied. • MoO₃ thin film electrode demonstrated enhanced electrochemical performance for energy storage capability. Molybdenum oxide thin film was deposited on indium tin oxide (ITO) coated glass via a simple and cost-effective approach. Some surface and electrochemical properties of the film were studied. Characteristic peaks from x-ray diffraction patterns indicated a well crystalline orthorhombic structure of MoO₃ thin film. Raman spectroscopy revealed Mo–O band bending in the range of wave number below 600 cm⁻¹ and stretching vibration modes in the higher range. Optical characterization showed that the film exhibited strong absorption in the ultraviolet (UV) and high optical transparency across visible light regions. Energy band gap was estimated between 3.36 and 3.44 eV while Urbach energy lied between 0.42 and 0.93 eV. Electrochemical performance of the film was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results showed that the film yielded relatively high specific capacitance of 220 F g⁻¹ and areal capacity of 4.94 mA h cm⁻². In addition, access to more active sites with minimum ion diffusion length of the MoO₃ electrode enhanced the redox behavior leading to superior rate capability and excellent long-term cycle stability on the substrate. This study presents a cost effective means of preparing nanoporous MoO₃ thin film from chemical reagents. It reveals charge transport capability of MoO₃ structure for optoelectronic and energy storage devices.