Abstract:
With its highly tunable electronic properties, doped graphene is a promising platform for next-generation electronic and photonic devices. Achieving selective and reliable n-type doping, together with controlled modulation of the Dirac point, is critical for the realization of high-performance graphene-based devices. Here, we report a simple and effective approach to modulate the electronic properties of single-layer graphene (SLG) using tungsten trioxide (WO3) nanoparticles prepared without the use of hazardous chemicals. The monoclinic crystal structure of the as-prepared WO3 nanoparticles was confirmed by X-ray diffraction and Raman spectroscopy, while transmission electron microscopy verified their uniform size and morphology. The electronic interaction between SLG and WO3 is systematically investigated by Raman spectroscopy, electrical transport measurements, and synchrotron-based photoelectron spectroscopy (PES) measurements. Our results reveal clear n-type doping of graphene with increasing WO3 nanoparticle concentrations (0.1, 0.3, and 0.5 mg mL−1). The corresponding shifts in Fermi energy and changes in sheet carrier concentration are quantitatively determined from transport and PES measurements. A maximum upward shift of the Fermi energy of approximately 200 meV and an electron density of up to ∼2.4 × 1012 cm−2 are achieved for SLG doped with 0.5 mg mL−1 WO3 nanoparticles. This cost-effective and straightforward surface-transfer doping approach offers a viable pathway for controlled electron doping in graphene, potentially facilitating the development of graphene-based electronic devices.