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<p>Graphene quantum dots (GQDs) have emerged as promising candidates for nanoscale optoelectronic and sensing devices due to their tunable electronic properties. However, achieving precise control over their band gap and reactivity remains a challenge. In this study, we employ density functional theory (DFT) calculations to investigate the impact of silicon (Si) doping at three distinct vacancy sites in GQDs. The computational analysis includes frontier molecular orbital (FMO) theory, density of states (DOS), molecular electrostatic potential (MEP), and chemical reactivity descriptors. Our results reveal that Si doping significantly reduces the band gap from 4.10&#xa0;eV in pristine GQD to 1.63&#xa0;eV, depending on the doping site. The study demonstrates enhanced charge transfer, localized electronic redistribution, and increased chemical reactivity at specific dopant positions. These findings suggest that site-selective Si doping provides a viable route for engineering GQDs with tailored electronic and optical properties. Future work could explore the experimental validation of these theoretical predictions and extend the approach to other dopant atoms or composite nanostructures.</p>

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Tuning the electronic and optical properties of graphene quantum dots by vacancy defect with Si-doping: DFT insights

  • 期刊论文

  • 发表日期：

    2025年6月21日

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

摘要

Graphene quantum dots (GQDs) have emerged as promising candidates for nanoscale optoelectronic and sensing devices due to their tunable electronic properties. However, achieving precise control over their band gap and reactivity remains a challenge. In this study, we employ density functional theory (DFT) calculations to investigate the impact of silicon (Si) doping at three distinct vacancy sites in GQDs. The computational analysis includes frontier molecular orbital (FMO) theory, density of states (DOS), molecular electrostatic potential (MEP), and chemical reactivity descriptors. Our results reveal that Si doping significantly reduces the band gap from 4.10 eV in pristine GQD to 1.63 eV, depending on the doping site. The study demonstrates enhanced charge transfer, localized electronic redistribution, and increased chemical reactivity at specific dopant positions. These findings suggest that site-selective Si doping provides a viable route for engineering GQDs with tailored electronic and optical properties. Future work could explore the experimental validation of these theoretical predictions and extend the approach to other dopant atoms or composite nanostructures.