Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications

  • Md Tanvir Hasan
  • Roberto Gonzalez-Rodriguez
  • Conor Ryan
  • Kristof Pota
  • Kayla Green
  • Jeffery L. Coffer
  • Anton V. NaumovEmail author
Research Article


In this work, we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal method. Structural and optical properties of as-produced NGQDs are further modified using controlled ozone treatment. Ozone-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and ID/IG Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen atoms. Along with structural modifications, GQDs experience decrease in ultraviolet–visible (UV–vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR) (up to 45 min treatment) fluorescence. This allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase, while controlled emission quenching was achieved by either blue laser or thermal treatment. Optimized Oz-NGQDs were further used to form a photoactive layer of solar cells with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current density. This study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.


nitrogen-doped graphene quantum dots ozone treatment optical properties photovoltaics solar cells 


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The authors would like to thank TCU for providing funding from the TCU RCAF (Research and Creative Activities Fund), and TCU Invests in Scholarship grant funding. Also, a grant from the Robert A. Welch Foundation (Grant P-1212 to JLC) is gratefully acknowledged.

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Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications


  1. [1]
    Sun, J.; Yang, S. W.; Wang, Z. Y.; Shen, H.; Xu, T.; Sun, L. T.; Li, H.; Chen, W. W.; Jiang, X. Y.; Ding, G. Q. et al. Ultra-high quantum yield of graphene quantum dots: Aromatic-nitrogen doping and photoluminescence mechanism. Part. Part. Syst. Charact. 2015, 32, 434–440.CrossRefGoogle Scholar
  2. [2]
    Niu, F. S.; Xu, Y. H.; Liu, J. X.; Song, Z. Q.; Liu, M. L.; Liu, J. Q. Controllable electrochemical/electroanalytical approach to generate nitrogen-doped carbon quantum dots from varied amino acids: Pinpointing the utmost quantum yield and the versatile photoluminescent and electrochemiluminescent applications. Electrochim. Acta 2017, 236, 239–251.CrossRefGoogle Scholar
  3. [3]
    Qu, D.; Zheng, M.; Zhang, L. G.; Zhao, H. F.; Xie, Z. G.; Jing, X. B.; Haddad, R. E.; Fan, H. Y.; Sun, Z. C. Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots. Sci. Rep. 2014, 4, 5294.CrossRefGoogle Scholar
  4. [4]
    Liu, Q.; Guo, B. D.; Rao, Z. Y.; Zhang, B. H.; Gong, J. R. Strong twophoton-induced fluorescence from photostable, biocompatible nitrogendoped graphene quantum dots for cellular and deep-tissue imaging. Nano Lett. 2013, 13, 2436–2441.CrossRefGoogle Scholar
  5. [5]
    Hasan, M. T.; Gonzalez-Rodriguez, R.; Ryan, C.; Faerber, N.; Coffer, J. L.; Naumov, A. V. Photo-and electroluminescence from nitrogen-doped and nitrogen–sulfur codoped graphene quantum dots. Adv. Funct. Mater. 2018, 28, 1804337.CrossRefGoogle Scholar
  6. [6]
    Zhou, L.; Geng, J. L.; Liu, B. Graphene quantum dots from polycyclic aromatic hydrocarbon for bioimaging and sensing of Fe3+ and hydrogen peroxide. Part. Part. Syst. Charact. 2013, 30, 1086–1092.CrossRefGoogle Scholar
  7. [7]
    Nurunnabi, M.; Khatun, Z.; Huh, K. M.; Park, S. Y.; Lee, D. Y.; Cho, K. J.; Lee, Y.-K. In vivo biodistribution and toxicology of carboxylated graphene quantum dots. ACS Nano 2013, 7, 6858–6867.CrossRefGoogle Scholar
  8. [8]
    Shang, W. H.; Zhang, X. Y.; Zhang, M.; Fan, Z. T.; Sun, Y.; Han, M.; Fan, L. Z. The uptake mechanism and biocompatibility of graphene quantum dots with human neural stem cells. Nanoscale 2014, 6, 5799–5806.CrossRefGoogle Scholar
  9. [9]
    Coe, S.; Woo, W.-K.; Bawendi, M.; Bulović, V. Electroluminescence from single monolayers of nanocrystals in molecular organic devices. Nature 2002, 420, 800–803.CrossRefGoogle Scholar
  10. [10]
    Tessler, N.; Medvedev, V.; Kazes, M.; Kan, S. H.; Banin, U. Efficient near-infrared polymer nanocrystal light-emitting diodes. Science 2002, 295, 1506–1508.CrossRefGoogle Scholar
  11. [11]
    Son, D. I.; Kwon, B. W.; Park, D. H.; Seo, W.-S.; Yi, Y.; Angadi, B.; Lee, C.-L.; Choi, W. K. Emissive ZnO–graphene quantum dots for white-lightemitting diodes. Nat. Nanotechnol. 2012, 7, 465–471.CrossRefGoogle Scholar
  12. [12]
    Moon, B. J.; Jang, D.; Yi, Y.; Lee, H.; Kim, S. J.; Oh, Y.; Lee, S. H.; Park, M.; Lee, S.; Bae, S. Multi-functional nitrogen self-doped graphene quantum dots for boosting the photovoltaic performance of BHJ solar cells. Nano Energy 2017, 34, 36–46.CrossRefGoogle Scholar
  13. [13]
    Carolan, D.; Rocks, C.; Padmanaban, D. B.; Maguire, P.; Svrcek, V.; Mariotti, D. Environmentally friendly nitrogen-doped carbon quantum dots for next generation solar cells. Sustainable Energy Fuels 2017, 1, 1611–1619.CrossRefGoogle Scholar
  14. [14]
    Gupta, V.; Chaudhary, N.; Srivastava, R.; Sharma, G. D.; Bhardwaj, R.; Chand, S. Luminscent graphene quantum dots for organic photovoltaic devices. J. Am. Chem. Soc. 2011, 133, 9960–9963.CrossRefGoogle Scholar
  15. [15]
    Wang, H.; Sun, P. F.; Cong, S.; Wu, J.; Gao, L. J.; Wang, Y.; Dai, X.; Yi, Q. H.; Zou, G. F. Nitrogen-doped carbon dots for “green” quantum dot solar cells. Nanoscale Res. Lett. 2016, 11, 27.CrossRefGoogle Scholar
  16. [16]
    Alivisatos, A. P.; Gu, W. W.; Larabell, C. Quantum dots as cellular probes. Annu. Rev. Biomed. Eng. 2005, 7, 55–76.CrossRefGoogle Scholar
  17. [17]
    Zhu, S. J.; Zhang, J. H.; Qiao, C. Y.; Tang, S. J.; Li, Y. F.; Yuan, W. J.; Li, B.; Tian, L.; Liu, F.; Hu, R. et al. Strongly green-photoluminescent graphene quantum dots for bioimaging applications. Chem. Commun. 2011, 47, 6858–6860.CrossRefGoogle Scholar
  18. [18]
    Ge, J. C.; Lan, M. H.; Zhou, B. J.; Liu, W. M.; Guo, L.; Wang, H.; Jia, Q. Y.; Niu, G. L.; Huang, X.; Zhou, H. Y. et al. A graphene quantum dot photodynamic therapy agent with high singlet oxygen generation. Nat. Commun. 2014, 5, 4596.CrossRefGoogle Scholar
  19. [19]
    Tabish, T. A.; Scotton, C. J.; Ferguson, D. C. J.; Lin, L. X.; van der Veen, A.; Lowry, S.; Ali, M.; Jabeen, F.; Ali, M.; Winyard, P. G. et al. Biocompatibility and toxicity of graphene quantum dots for potential application in photodynamic therapy. Nanomedicine 2018, 13, 1923–1937.CrossRefGoogle Scholar
  20. [20]
    Zeng, Z. P.; Chen, S. F.; Tan, T. T. Y.; Xiao, F.-X. Graphene quantum dots (GQDs) and its derivatives for multifarious photocatalysis and photoelectrocatalysis. Catal. Today 2018, 315, 171–183.CrossRefGoogle Scholar
  21. [21]
    Lu, Q.; Zhang, Y. J.; Liu, S. Q. Graphene quantum dots enhanced photocatalytic activity of zinc porphyrin toward the degradation of methylene blue under visible-light irradiation. J. Mater. Chem. A 2015, 3, 8552–8558.CrossRefGoogle Scholar
  22. [22]
    Tao, H. Q.; Yang, K.; Ma, Z.; Wan, J. M.; Zhang, Y. J.; Kang, Z. H.; Liu, Z. In vivo NIR fluorescence imaging, biodistribution, and toxicology of photoluminescent carbon dots produced from carbon nanotubes and graphite. Small 2012, 8, 281–290.CrossRefGoogle Scholar
  23. [23]
    Dong, Y. Q.; Chen, C. Q.; Zheng, X. T.; Gao, L. L.; Gui, Z. M.; Yang, H. B.; Guo, C. X.; Chi, Y. W.; Li, C. M. One-step and high yield simultaneous preparation of single-and multi-layer graphene quantum dots from CX-72 carbon black. J. Mater. Chem. 2012, 22, 8764–8766.CrossRefGoogle Scholar
  24. [24]
    Li, H. T.; He, X. D.; Kang, Z. H.; Huang, H.; Liu, Y.; Liu, J. L.; Lian, S. Y.; Tsang, C. H. A.; Yang, X. B.; Lee, S.-T. Water-soluble fluorescent carbon quantum dots and photocatalyst design. Angew. Chem., Int. Ed. 2010, 49, 4430–4434.CrossRefGoogle Scholar
  25. [25]
    Li, Y.; Hu, Y.; Zhao, Y.; Shi, G. Q.; Deng, L. E.; Hou, Y. B.; Qu, L. T. An electrochemical avenue to green-luminescent graphene quantum dots as potential electron-acceptors for photovoltaics. Adv. Mater. 2011, 23, 776–780.CrossRefGoogle Scholar
  26. [26]
    Liu, R. L.; Wu, D. Q.; Feng, X. L.; Müllen, K. Bottom-up fabrication of photoluminescent graphene quantum dots with uniform morphology. J. Am. Chem. Soc. 2011, 133, 15221–15223.CrossRefGoogle Scholar
  27. [27]
    Liu, C. J.; Zhang, P.; Tian, F.; Li, W. C.; Li, F.; Liu, W. G. One-step synthesis of surface passivated carbon nanodots by microwave assisted pyrolysis for enhanced multicolor photoluminescence and bioimaging. J. Mater. Chem. 2011, 21, 13163–13167.CrossRefGoogle Scholar
  28. [28]
    Zhai, X. Y.; Zhang, P.; Liu, C. J.; Bai, T.; Li, L. M.; Dai, L. M.; Liu, W. G. Highly luminescent carbon nanodots by microwave-assisted pyrolysis. Chem. Commun. 2012, 48, 7955–7957.CrossRefGoogle Scholar
  29. [29]
    Wang, L.; Zhu, S.-J.; Wang, H.-Y.; Qu, S.-N.; Zhang, Y.-L.; Zhang, J.-H.; Chen, Q.-D.; Xu, H.-L.; Han, W.; Yang, B. et al. Common origin of green luminescence in carbon nanodots and graphene quantum dots. ACS Nano 2014, 8, 2541–2547.CrossRefGoogle Scholar
  30. [30]
    Wang, L.; Wang, H. Y.; Wang, Y.; Zhu, S. J.; Zhang, Y. L.; Zhang, J. H.; Chen, Q. D.; Han, W.; Xu, H. L.; Yang, B. et al. Direct observation of quantum-confined graphene-like states and novel hybrid states in graphene oxide by transient spectroscopy. Adv. Mater. 2013, 25, 6539–6545.CrossRefGoogle Scholar
  31. [31]
    Yang, Z.-C.; Li, X.; Wang, J. Intrinsically fluorescent nitrogen-containing carbon nanoparticles synthesized by a hydrothermal process. Carbon 2011, 49, 5207–5212.CrossRefGoogle Scholar
  32. [32]
    Bao, L.; Zhang, Z.-L.; Tian, Z.-Q.; Zhang, L.; Liu, C.; Lin, Y.; Qi, B. P.; Pang, D.-W. Electrochemical tuning of luminescent carbon nanodots: From preparation to luminescence mechanism. Adv. Mater. 2011, 23, 5801–5806.CrossRefGoogle Scholar
  33. [33]
    Shang, J. Z.; Ma, L.; Li, J. W.; Ai, W.; Yu, T.; Gurzadyan, G. G. The origin of fluorescence from graphene oxide. Sci. Rep. 2012, 2, 792.CrossRefGoogle Scholar
  34. [34]
    Mirtchev, P.; Henderson, E. J.; Soheilnia, N.; Yip, C. M.; Ozin, G. A. Solution phase synthesis of carbon quantum dots as sensitizers for nanocrystalline TiO2 solar cells. J. Mater. Chem. 2012, 22, 1265–1269.CrossRefGoogle Scholar
  35. [35]
    Zhang, Y.-Q.; Ma, D.-K.; Zhang, Y.-G.; Chen, W.; Huang, S.-M. N-doped carbon quantum dots for TiO2-based photocatalysts and dye-sensitized solar cells. Nano Energy 2013, 2, 545–552.CrossRefGoogle Scholar
  36. [36]
    Briscoe, J.; Marinovic, A.; Sevilla, M.; Dunn, S.; Titirici, M. Biomassderived carbon quantum dot sensitizers for solid-state nanostructured solar cells. Angew. Chem., Int. Ed. 2015, 54, 4463–4468.CrossRefGoogle Scholar
  37. [37]
    Kwon, W.; Lee, G.; Do, S.; Joo, T.; Rhee, S. W. Size-controlled softtemplate synthesis of carbon nanodots toward versatile photoactive materials. Small 2014, 10, 506–513.CrossRefGoogle Scholar
  38. [38]
    Narayanan, R.; Deepa, M.; Srivastava, A. K. Förster resonance energy transfer and carbon dots enhance light harvesting in a solid-state quantum dot solar cell. J. Mater. Chem. A 2013, 1, 3907–3918.CrossRefGoogle Scholar
  39. [39]
    Qian, F. L.; Li, X. M.; Tang, L. B.; Lai, S. K.; Lu, C. Y.; Lau, S. P. Potassium doping: Tuning the optical properties of graphene quantum dots. AIP Adv. 2016, 6, 075116.CrossRefGoogle Scholar
  40. [40]
    Dong, Y.; Zhang, S.; Shi, L. L.; Chen, Y. X.; Ma, J.; Guo, S. S.; Chen, X. H.; Song, H. H. The photoluminescence of step-wise reduced graphene oxide quantum dots. Mater. Chem. Phys. 2018, 203, 125–132.CrossRefGoogle Scholar
  41. [41]
    Jin, S. H.; Kim, D. H.; Jun, G. H.; Hong, S. H.; Jeon, S. Tuning the photoluminescence of graphene quantum dots through the charge transfer effect of functional groups. ACS Nano 2013, 7, 1239–1245.CrossRefGoogle Scholar
  42. [42]
    Basak, T.; Basak, T. Effect of carrier doping and external electric field on the optical properties of graphene quantum dots. IOP Conf. Ser.: Mater. Sci. Eng. 2018, 310, 012014.CrossRefGoogle Scholar
  43. [43]
    Hai, X.; Feng, J.; Chen, X. W.; Wang, J. H. Tuning the optical properties of graphene quantum dots for biosensing and bioimaging. J. Mater. Chem. B 2018, 6, 3219–3234.CrossRefGoogle Scholar
  44. [44]
    Zhao, M. L. Direct synthesis of graphene quantum dots with different fluorescence properties by oxidation of graphene oxide using nitric acid. Appl. Sci. 2018, 8, 1303.CrossRefGoogle Scholar
  45. [45]
    Yu, P.; Wen, X. M.; Toh, Y.-R.; Tang, J. Temperature-dependent fluorescence in carbon dots. J. Phys. Chem. C 2012, 116, 25552–25557.CrossRefGoogle Scholar
  46. [46]
    Tian, Y.; Li, L.; Guo, X.; Wójtowicz, A.; Estevez, L.; Krysmann, M. J.; Kelarakis, A. Dramatic photoluminescence quenching in carbon dots induced by cyclic voltammetry. Chem. Commun. 2018, 54, 9067–9070.CrossRefGoogle Scholar
  47. [47]
    Gao, F. H.; Liu, F. C.; Bai, X. H.; Xu, X. F.; Kong, W. J.; Liu, J.; Lv, F. Z.; Long, L. Z.; Yang, Y.; Li, M. Tuning the photoluminescence of graphene oxide quantum dots by photochemical fluorination. Carbon 2019, 141, 331–338.CrossRefGoogle Scholar
  48. [48]
    Hasan, M. T.; Senger, B. J.; Mulford, P.; Ryan, C.; Doan, H.; Gryczynski, Z.; Naumov, A. V. Modifying optical properties of reduced/graphene oxide with controlled ozone and thermal treatment in aqueous suspensions. Nanotechnology 2017, 28, 065705.CrossRefGoogle Scholar
  49. [49]
    Hasan, M. T.; Senger, B. J.; Ryan, C.; Culp, M.; Gonzalez-Rodriguez, R.; Coffer, J. L.; Naumov, A. V. Optical band gap alteration of graphene oxide via ozone treatment. Sci. Rep. 2017, 7, 6411.CrossRefGoogle Scholar
  50. [50]
    Wang, L.; Wang, Y. L.; Xu, T.; Liao, H. B.; Yao, C. J.; Liu, Y.; Li, Z.; Chen, Z. W.; Pan, D. Y.; Sun, L. T. et al. Gram-scale synthesis of singlecrystalline graphene quantum dots with superior optical properties. Nat. Commun. 2014, 5, 5357.CrossRefGoogle Scholar
  51. [51]
    Yang, Q. M.; Duan, J. L.; Yang, W.; Li, X. M.; Mo, J. H.; Yang, P. Z.; Tang, Q. W. Nitrogen-doped carbon quantum dots from biomass via simple one-pot method and exploration of their application. Appl. Surf. Sci. 2018, 434, 1079–1085.CrossRefGoogle Scholar
  52. [52]
    Fan, X. B.; Peng, W. C.; Li, Y.; Li, X. Y.; Wang, S. L.; Zhang, G. L.; Zhang, F. B. Deoxygenation of exfoliated graphite oxide under alkaline conditions: A green route to graphene preparation. Adv. Mater. 2008, 20, 4490–4493.CrossRefGoogle Scholar
  53. [53]
    Cai, W. W.; Piner, R. D.; Stadermann, F. J.; Park, S.; Shaibat, M. A.; Ishii, Y.; Yang, D. X.; Velamakanni, A.; An, S. J.; Stoller, M. et al. Synthesis and solid-state NMR structural characterization of 13C-labeled graphite oxide. Science 2008, 321, 1815–1817.CrossRefGoogle Scholar
  54. [54]
    He, H. Y.; Riedl, T.; Lerf, A.; Klinowski, J. Solid-state NMR studies of the structure of graphite oxide. J. Phys. Chem. 1996, 100, 19954–19958.CrossRefGoogle Scholar
  55. [55]
    Gu, J.; Zhang, Z. P.; Peng, A. M.; Yang, J. Facile synthesis and photoluminescence characteristics of blue-emitting nitrogen-doped graphene quantum dots. Nanotechnology 2016, 27, 165704.CrossRefGoogle Scholar
  56. [56]
    Ben Aoun, S. Nanostructured carbon electrode modified with N-doped graphene quantum dots–chitosan nanocomposite: A sensitive electrochemical dopamine sensor. R. Soc. Open Sci. 2017, 4, 171199.CrossRefGoogle Scholar
  57. [57]
    Kwon, W.; Kim, Y.-H.; Lee, C.-L.; Lee, M.; Choi, H. C.; Lee, T.-W.; Rhee, S.-W. Electroluminescence from graphene quantum dots prepared by amidative cutting of tattered graphite. Nano Lett. 2014, 14, 1306–1311.CrossRefGoogle Scholar
  58. [58]
    Guo, X. C.; Zhang, H. Y.; Sun, H. Q.; Tade, M. O.; Wang, S. B. Green synthesis of carbon quantum dots for sensitized solar cells. ChemPhotoChem 2017, 1, 116–119.CrossRefGoogle Scholar
  59. [59]
    Vougioukalakis, G. C.; Philippopoulos, A. I.; Stergiopoulos, T.; Falaras, P. Contributions to the development of ruthenium-based sensitizers for dye-sensitized solar cells. Coord. Chem. Rev. 2011, 255, 2602–2621.CrossRefGoogle Scholar
  60. [60]
    Lu, K. Y.; Wang, Y. J.; Liu, Z. K.; Han, L.; Shi, G. Z.; Fang, H. H.; Chen, J.; Ye, X. C.; Chen, S.; Yang, F. et al. High-efficiency PbS quantum-dot solar cells with greatly simplified fabrication processing via “Solvent-Curing”. Adv. Mater. 2018, 30, 1707572.CrossRefGoogle Scholar
  61. [61]
    Huang, F.; Zhang, L. S.; Zhang, Q. F.; Hou, J.; Wang, H. G.; Wang, H. L.; Peng, S. L.; Liu, J. S.; Cao, G. Z. High efficiency CdS/CdSe quantum dot sensitized solar cells with two ZnSe layers. ACS Appl. Mater. Interfaces 2016, 8, 34482–34489.CrossRefGoogle Scholar
  62. [62]
    Derfus, A. M.; Chan, W. C. W.; Bhatia, S. N. Probing the cytotoxicity of semiconductor quantum dots. Nano Lett. 2004, 4, 11–18.CrossRefGoogle Scholar
  63. [63]
    Bottrill, M.; Green, M. Some aspects of quantum dot toxicity. Chem. Commun. 2011, 47, 7039–7050.CrossRefGoogle Scholar
  64. [64]
    Ba, L. X.; Liu, H.; Shen, W. Z. Perovskite/c-Si tandem solar cells with realistic inverted architecture: Achieving high efficiency by optical optimization. Prog. Photovolt.: Res. Appl. 2018, 26, 924–933.CrossRefGoogle Scholar
  65. [65]
    Shahrjerdi, D.; Bedell, S. W.; Bayram, C.; Lubguban, C. C.; Fogel, K.; Lauro, P.; Ott, J. A.; Hopstaken, M.; Gayness, M.; Sadana, D. Ultralight high-efficiency flexible InGaP/(In)GaAs tandem solar cells on plastic. Adv. Energy Mater. 2013, 3, 566–571.CrossRefGoogle Scholar

Copyright information

© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Md Tanvir Hasan
    • 1
  • Roberto Gonzalez-Rodriguez
    • 1
  • Conor Ryan
    • 1
  • Kristof Pota
    • 2
  • Kayla Green
    • 2
  • Jeffery L. Coffer
    • 2
  • Anton V. Naumov
    • 1
    Email author
  1. 1.Department of Physics and AstronomyTexas Christian UniversityFort WorthUSA
  2. 2.Department of Chemistry and BiochemistryTexas Christian UniversityFort WorthUSA

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