Enhanced performance of dye-sensitized solar cell with thermally stable natural dye-assisted TiO2/MnO2 bilayer-assembled photoanode

Abstract

This study reports the performance analysis of an organic dye-sensitized solar cell (DSSC), introducing MnO₂ as an electron transport layer in TiO₂/MnO₂ bilayer assembly. The DSSCs have been fabricated using TiO₂ and TiO₂/MnO₂ layer-by-layer architecture films onto fluorine-doped tin oxide (FTO) glass and sensitized with natural dye extracted from Malvaviscus penduliflorus flower in ethanol medium. The counter electrode was prepared to layer copper powder containing paste onto FTO's conductive side by the doctor's blade method. The optical, morphological, and structural properties of photoanodes were explored via ultraviolet–visible, field emission scanning electron microscopy, and X-ray diffraction analyses. Moreover, dye complexity and thermostability of dyes were characterized via Fourier-transform infrared spectroscopy and thermogravimetric analyses. The iodide/triiodide (i.e., I^?/I₃^?) redox couple of electrolyte solution was employed as a charge transport medium between the electrodes. Finally, photoanode and counter electrode sandwiches were assembled to envisage the photovoltaic performance potential under simulated AM 1.5G solar illumination using 100 mW cm^–2 light intensity. The as-fabricated DSSC comprising TiO₂/MnO₂ bilayer assembly exhibited 6.02?mA?cm^–2 short circuit current density (J_sc), 0.38?V open-circuit voltage (V_oc), 40.38% fill factor, and 0.92% conversion efficiency, which is about 200% higher compared to the assembly devoid of MnO₂ layer.