DFT Study on Optoelectronic Properties of Graphene Quantum Dots with Various Sulfur Doping Patterns

This study explores the effects of sulfur doping on the electronic and optical properties of Graphene Quantum Dots (GQDs) using Density Functional Theory (DFT). Three sulfur doping configurations are analyzed: substitutional doping (Sg), where sulfur atoms replace carbon atoms in the graphene lattice, edge/terminal doping (Sh), where sulfur is added at the edges or terminals, and thiophene-like doping (Sp), where sulfur is incorporated into five-membered rings at the graphene edges. The results show that sulfur doping reduces the energy gap of GQDs, with values of 1.444 eV for Sg, 1.213 eV for Sh, and 1.487 eV for Sp, indicating enhanced electrical conductivity and electronic reactivity. Optical absorption spectra reveal a redshift in the sulfur-doped GQDs compared to pristine GQDs, with absorption peaks at 858.7 nm for Sg, 1022.2 nm for Sh, and 833.9 nm for Sp, demonstrating their potential for applications in optoelectronic devices such as sensors and photodetectors. These findings highlight the significant impact of sulfur doping on the properties of GQDs, making them promising candidates for use in various nanoelectronic and optoelectronic applications.

Graphene Quantum Dots, Sulfur Doping, Density Functional Theory

1. S. A. Ansari, "Graphene quantum dots: novel properties and their applications for energy storage devices," Nanomaterials, vol. 12, no. 21, p. 3814, 2022. [Google Scholar] [Crossref]

2. Y. R. Kumar, K. Deshmukh, K. K. Sadasivuni, and S. K. Pasha, "Graphene quantum dot based materials for sensing, bio-imaging and energy storage applications: a review," RSC advances, vol. 10, no. 40, pp. 23861-23898, 2020. [Google Scholar] [Crossref]

3. S. T. Jalood, Z. A. A. Alhasani, and F. N. Ajeel, "Engineering the Electronic and Optical Properties of Graphene Quantum Dots via NiO Dimer: A DFT Investigation," Transactions on Electrical and Electronic Materials, pp. 1-11, 2025. [Google Scholar] [Crossref]

4. F. N. Ajeel, N. B. Shwayyea, M. K. Salman, A. M. Khudhair, and A. B. Ahmed, "Tuning the electronic and optical properties of graphene quantum dots by vacancy defect with Si-doping: DFT insights," Applied Physics B, vol. 131, no. 7, p. 143, 2025. [Google Scholar] [Crossref]

5. S.-Y. Li and L. He, "Recent progresses of quantum confinement in graphene quantum dots," Frontiers of Physics, vol. 17, no. 3, p. 33201, 2022. [Google Scholar] [Crossref]

6. N. Gupta et al., "Large-scale efficient mid-wave infrared optoelectronics based on black phosphorus ink," Science Advances, vol. 9, no. 49, p. eadi9384, 2023. [Google Scholar] [Crossref]

7. H. Cho, G. Bae, and B. H. Hong, "Engineering functionalization and properties of graphene quantum dots (GQDs) with controllable synthesis for energy and display applications," Nanoscale, vol. 16, no. 7, pp. 3347-3378, 2024. [Google Scholar] [Crossref]

8. M. Kadhem, N. B. S. Ajeel, F. N. Ajeel, and A. M. Khudhair, "Investigating the Effects of TiO Impurities on the Electronic Properties of Graphene Nanoflakes Using DFT Method," Sumer Journal for Pure Science, 2024. [Google Scholar] [Crossref]

9. I. V. Ershov, A. A. Lavrentyev, D. L. Romanov, and O. M. Holodova, "Tuning Optical Excitations of Graphene Quantum Dots Through Selective Oxidation: Effect of Epoxy Groups," C, vol. 11, no. 3, p. 51, 2025. [Google Scholar] [Crossref]

10. W. Liu, Y. Han, M. Liu, L. Chen, and J. Xu, "Effect of defects on optical and electronic properties of graphene quantum dots: a density functional theory study," RSC advances, vol. 13, no. 24, pp. 16232-16240, 2023. [Google Scholar] [Crossref]

11. S. K. Khamees, F. N. Ajeel, K. H. Mohsin, and M. N. Mutier, "Influence of B, si, ge, and as impurities on the electronic properties of graphene quantum dot: A density functional theory study," Nano Trends, vol. 7, p. 100049, 2024. [Google Scholar] [Crossref]

12. F. Ajeel and K. T. Yalkhoum, "Tuning the Electronic Properties of Graphene through MgO Impurities: DFT Investigations," Sumer journal for Pure Science, 2024. [Google Scholar] [Crossref]

13. J. Feng, H. Dong, L. Yu, and L. Dong, "The optical and electronic properties of graphene quantum dots with oxygen-containing groups: a density functional theory study," Journal of Materials Chemistry C, vol. 5, no. 24, pp. 5984-5993, 2017. [Google Scholar] [Crossref]

14. S. Kaushal, M. Kaur, N. Kaur, V. Kumari, and P. P. Singh, "Heteroatom-doped graphene as sensing materials: A mini review," RSC advances, vol. 10, no. 48, pp. 28608-28629, 2020. [Google Scholar] [Crossref]

15. N. Sohal, B. Maity, and S. Basu, "Recent advances in heteroatom-doped graphene quantum dots for sensing applications," RSC advances, vol. 11, no. 41, pp. 25586-25615, 2021. [Google Scholar] [Crossref]

16. F. N. Ajeel, M. N. Mutier, K. H. Mohsin, S. K. Khamees, A. M. Khudhair, and A. B. Ahmed, "Theoretical study on electronic properties of BN dimers doped graphene quantum dots," BioNanoScience, vol. 14, no. 2, pp. 1110-1118, 2024. [Google Scholar] [Crossref]

17. R. Rabeya, S. Mahalingam, A. Manap, M. Satgunam, M. Akhtaruzzaman, and C. H. Chia, "Structural defects in graphene quantum dots: A review," International Journal of Quantum Chemistry, vol. 122, no. 12, p. e26900, 2022. [Google Scholar] [Crossref]

18. A. Kalluri, B. Dharmadhikari, D. Debnath, P. Patra, and C. V. Kumar, "Advances in structural modifications and properties of graphene quantum dots for biomedical applications," ACS omega, vol. 8, no. 24, pp. 21358-21376, 2023. [Google Scholar] [Crossref]

19. I. Shtepliuk and R. Yakimova, "Nature of photoexcited states in ZnO-embedded graphene quantum dots," Physical Chemistry Chemical Physics, vol. 25, no. 15, pp. 10525-10535, 2023. [Google Scholar] [Crossref]

20. P. Ramachandran et al., "N-doped graphene quantum dots/titanium dioxide nanocomposites: A study of ROS-forming mechanisms, cytotoxicity and photodynamic therapy," Biomedicines, vol. 10, no. 2, p. 421, 2022. [Google Scholar] [Crossref]

21. J. Feng et al., "Density functional theory study on optical and electronic properties of co-doped graphene quantum dots based on different nitrogen doping patterns," Diamond and Related Materials, vol. 113, p. 108264, 2021. [Google Scholar] [Crossref]

22. J. Feng et al., "Theoretical study on the optical and electronic properties of graphene quantum dots doped with heteroatoms," Physical Chemistry Chemical Physics, vol. 20, no. 22, pp. 15244-15252, 2018. [Google Scholar] [Crossref]

23. J. Feng et al., "Theoretical insights into tunable optical and electronic properties of graphene quantum dots through phosphorization," Carbon, vol. 155, pp. 491-498, 2019. [Google Scholar] [Crossref]

24. P. Rani, R. Dalal, and S. Srivastava, "Effect of surface modification on optical and electronic properties of graphene quantum dots," Applied Surface Science, vol. 609, p. 155379, 2023. [Google Scholar] [Crossref]

25. E. V. Gómez, N. A. Ramirez Guarnizo, J. D. Perea, A. S. López, and J. J. Prías-Barragán, "Exploring molecular and electronic property predictions of reduced graphene oxide nanoflakes via density functional theory," ACS omega, vol. 7, no. 5, pp. 3872-3880, 2022. [Google Scholar] [Crossref]

26. D. M. Mamand and H. M. Qadr, "Corrosion inhibition efficiency and quantum chemical studies of some organic compounds: theoretical evaluation," Corrosion Reviews, vol. 41, no. 4, pp. 427-441, 2023. [Google Scholar] [Crossref]

27. F. N. Ajeel, Y. W. Ouda, and S. A. Abdullah, "Graphene nanoflakes as a nanobiosensor for amino acid profiles of fish products: Density functional theory investigations," Drug Invention Today, vol. 12, no. 12, p. 9, 2019. [Google Scholar] [Crossref]

28. H.-g. Kim and H. J. Choi, "Thickness dependence of work function, ionization energy, and electron affinity of Mo and W dichalcogenides from DFT and GW calculations," Physical review B, vol. 103, no. 8, p. 085404, 2021. [Google Scholar] [Crossref]

29. Y. Oh, S. Song, and J. Bae, "A review of bandgap engineering and prediction in 2D material heterostructures: a DFT perspective," International Journal of Molecular Sciences, vol. 25, no. 23, p. 13104, 2024. [Google Scholar] [Crossref]

30. K. H. Bardan, F. N. Ajeel, M. H. Mohammed, A. M. Khudhair, and A. B. Ahmed, "DFT study of adsorption properties of the ammonia on both pristine and Si-doped graphene nanoflakes," Chemical Physics Impact, vol. 8, p. 100561, 2024. [Google Scholar] [Crossref]

31. F. N. Ajeel, S. K. Khamees, K. H. Mohsin, and M. N. Mutier, "Effect of AlN dimers on the electronic properties of graphene quantum dot: DFT investigations," Chemical Physics Impact, vol. 7, p. 100364, 2023. [Google Scholar] [Crossref]

32. F. N. Ajeel, K. H. Mohsin, H. G. Shakier, S. K. Khamees, and M. N. Mutier, "Theoretical insights into tunable electronic properties of graphene quantum dots through ZnO doping," Chemical Physics Impact, vol. 7, p. 100305, 2023. [Google Scholar] [Crossref]

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