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<p>Graphene quantum dots (GQDs) have emerged as promising nanomaterials for next-generation optoelectronic, sensing, and energy applications owing to their size-dependent electronic and optical properties. However, precise control over their band structures and chemical reactivities remains a significant challenge. In this study, we employed density functional theory to systematically investigate the impact of oxygen doping and structural vacancy defects on the electronic, optical, and chemical properties of GQDs. Our results reveal that introducing vacancy defects significantly reduces the band gap from 2.717 eV in pristine GQDs to as low as 0.479 eV enhancing electrical conductivity by several orders of magnitude. Furthermore, site- and concentration-specific oxygen doping modulates key descriptors such as formation energy, chemical potential, global hardness, and electrophilicity. The lowest formation energy (− 82.383 eV) and highest conductivity (95 S/m) were achieved in GQDs with three oxygen atoms, confirming their thermodynamic and electronic favorability. Analysis of the optical absorption spectra revealed a tunable threshold extending from the visible to mid-wave infrared (MWIR) regions, emphasizing the material’s adaptability for light-harvesting technologies. This study demonstrates the potential of defect and dopant engineering to effectively modulate the properties of GQDs, paving the way for their optimized design in advanced nanoelectronics and optoelectronic systems.</p>

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Engineering the electronic and optical properties of graphene quantum dot via oxygen doping and structural defects: a DFT-based approach

  • 期刊论文

  • 发表日期：

    2026年6月20日

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  • Noora B. Shwayyea,
  • Fouad N. Ajeel,
  • Mustafa K. Salman,
  • Alaa M. Khudhair,
  • Ali Ben Ahmed

摘要

Graphene quantum dots (GQDs) have emerged as promising nanomaterials for next-generation optoelectronic, sensing, and energy applications owing to their size-dependent electronic and optical properties. However, precise control over their band structures and chemical reactivities remains a significant challenge. In this study, we employed density functional theory to systematically investigate the impact of oxygen doping and structural vacancy defects on the electronic, optical, and chemical properties of GQDs. Our results reveal that introducing vacancy defects significantly reduces the band gap from 2.717 eV in pristine GQDs to as low as 0.479 eV enhancing electrical conductivity by several orders of magnitude. Furthermore, site- and concentration-specific oxygen doping modulates key descriptors such as formation energy, chemical potential, global hardness, and electrophilicity. The lowest formation energy (− 82.383 eV) and highest conductivity (95 S/m) were achieved in GQDs with three oxygen atoms, confirming their thermodynamic and electronic favorability. Analysis of the optical absorption spectra revealed a tunable threshold extending from the visible to mid-wave infrared (MWIR) regions, emphasizing the material’s adaptability for light-harvesting technologies. This study demonstrates the potential of defect and dopant engineering to effectively modulate the properties of GQDs, paving the way for their optimized design in advanced nanoelectronics and optoelectronic systems.