Carbon dots (CDs) synthesis and photophysical properties in solution

The method of synthesis, schematically presented below, has followed our previous approach – starting from commercial carbon nanoparticles of diameters below 50 nm. After oxidation, the surface of the carbon nanoparticles was treated in thionyl chloride, with a subsequent amidation reaction by two types of amine terminated derivatives (e.g. p-phenylenediamine) to yield pPD-CDs. The synthesis was carried out under argon atmosphere for 3 days with the successive size separation on Sephadex.

Fig. 1 Schematic illustration of the  pPD-CDs synthesis

The synthesized carbon dots exhibited the characteristic excitation-dependent emission (Fig. 2) with a broad emission and emission centered at 450 nm for pPD-CDs. In addition to the intense excitation-dependent emission, with shifting the excitation wavelength above 420 nm, there is a fixed emission centered at around 570 nm.

Fig.2 PL spectra of   pDA-CD aqueous solutions at indicated excitation wavelengths

Carbon dot - based white light-emitting diodes (CD-WLED)

• Demonstrated and laboratory-validated the feasibility of efficient and stable electrically excited carbon dot-based white light emitting devices (CD-WLED)
• Realization of the CD-WLED - Assembly and packaging at the laboratory level
• Design and configuration of the experimental setup for EL measurements
• Final assembly of the device, electrical contacts and encapsulation
• Operational stability under laboratory conditions

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Dissemination

1. Conference: Advancements in white electroluminescent carbon dot-based light emitting diodes, O. Ligor, D. Bogosel, E. M. Pavelescu, A. Istrate , F. Nastase, I. Mihalache, E. Vasile, A. Terec, L. M. Veca, Nanotech France 2022

2. Patent application: Diode emitatoare de lumina alba pe baza de „carbon dots” electroluminescente LM. Veca, F. Nastase, AI Istrate, O Ligor, DF Bogosel, A Terec, A/00660 OSIM 20.10.2022

3. Article „Ca-Doped ZnO:Al Thin Films: Synthesis and Characterization” Anca-Ionela Istrate, Iuliana Mihalache, Cosmin Romanitan, Oana Tutunaru, Silviu Vulpe, Florin Nastase and Lucia Monica Veca Coatings 2021, 11(9), 1023;  doi:10.3390/coatings11091023