Facile Synthesis of Ultrathin 2D Tungsten Oxide Nanosheet as a Next-Generation Material for Enhanced Solar Conversion Efficiency

Abstract

The global energy crisis and dependency on fossil fuels have compelled us to rely on renewable energy-based technology, a more sustainable, eco-friendly energy source. Dye-sensitized solar cells (DSSCs) are one such promising technology. Owing to its unique features, the two-dimensional (2D) tungsten oxide nanosheet is a top-notch photoactive material for DSSC applications. However, their extensive commercialization is limited by cost-efficient and environmentally benign synthesis of an ultrathin 2D nanosheets. In this work, an easily scalable and high-yield mechanochemical synthesis of ultrathin nanosheets has been proposed at ambient temperature. The phase evolution and formation mechanism of the WO₃ nanosheet has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) images. The as-synthesized WO₃ nanosheets were structurally characterized by multiple techniques like XRD, Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Raman, and ultraviolet–visible (UV–vis), while the nanoplate-like surface morphology was characterized by microscopic techniques like field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), and atomic force microscopy (AFM). The synthesized nanosheet was combined with a highly conductive graphene sheet (GS) in different doping percentages, and such modified hybrid systems were tested for DSSC application. Under the simulation of one-sun illumination, the DSSC using pristine photoelectrode material demonstrated a solar-power conversion efficiency of 9.31%, while the optimal doping of 0.6 wt % GS exhibited excellent performance with the highest power conversion efficiency of 10.47%, improved IPCE, and long term stability. A device prototype of the DSSC was developed utilizing the same, which continued to perform well for almost 3 months with a meagre loss in its performance. This work provides a promising approach for increasing the efficiency of solar cells by altering the WO₃ photoelectrode with GS, which acted as a next-generation material for commercializing DSSCs.