Monochromatic Blue and Switchable Blue-Green Carbon Quantum Dots by Room-Temperature Air Plasma Processing

Janith Weerasinghe, James Scott, Athukoralalage Don K. Deshan, Dechao Chen, Amandeep Singh, Suvankar Sen, Prashant Sonar, Krasimir Vasilev, Qin Li, Kostya (Ken) Ostrikov

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Carbon quantum dots (CQDs, C-dots or CDs) are an emerging type of nanomaterial which has received immense attention due to their numerous applications. However, most of the reported CQDs in literature typically emit single emission peak under an excitation. Multipeak emissions without any complicated techniques will be ideal for various applications in the fields of ratiometric sensing, optoelectronics, and multifunctional bio-imaging systems. Here, a fast, effective, and single-step method is developed for the bulk synthesis of CQDs using atmospheric pressure air plasmas. Structural, morphological, and chemical properties are characterized by advanced analytical techniques. The CQDs have an average diameter of about 3 nm with a narrow size distribution. Emission wavelengths of 470 nm for blue emissive CQDs and 515 nm for green emissive CQDs are observed. Concentration dependency of the CQDs suggests that the switchable mechanism is due to the formation of PTSA excimers. Dual-emissive CQDs have the potential to be used in bi-channel ratiometric determination for metal ions, pH sensing, tumor diagnosis and detection, and solid-state lighting materials. The proof-of-principle demonstration of the use of dual-emissive CQDs (DCQDs) as a fluorescent sensor of Cu2+ ions is also presented to highlight the possible applications.

Original languageEnglish
Article number2100586
Number of pages9
JournalAdvanced Materials Technologies
Issue number4
Publication statusPublished - Apr 2022
Externally publishedYes


  • atmospheric pressure plasma
  • carbon quantum dots
  • copper ion sensing
  • dual emissive carbon dots


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