Nitrogen-doped carbon dots in Na₂B₄O₇ matrix: Excitation-dependent phosphorescence for multi-level encryption

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Achieving efficient room-temperature phosphorescence (RTP) requires rigid microenvironments and enhanced intersystem crossing (ISC).
• Designing highly efficient RTP carbon dots (CDs) presents a significant challenge in materials science.

Purpose of the Study:

• To develop novel RTP carbon dots (CDs) with enhanced efficiency and tunable emission properties.
• To explore the synergistic effects of heteroatom doping and matrix-assisted synthesis for RTP enhancement.

Main Methods:

• Fabrication of B, N-doped carbon dots (N-CDs) encapsulated within a sodium tetraborate (Na2B4O7) matrix.
• Utilizing N-doping to facilitate ISC and the Na2B4O7 matrix to prevent environmental quenching.
• Characterization using X-ray Photoelectron Spectroscopy (XPS) to confirm material composition and structure.

Main Results:

• The N-CDs@Na2B4O7 composite exhibited long-lived and color-tunable RTP emission.
• RTP lifetime was significantly extended from 32.79 ms to 122.00 ms upon matrix incorporation.
• Demonstrated wavelength-dependent RTP color variation, enabling multi-level information encryption and berberine hydrochloride (BRH) detection via inner filter effect (IFE).

Conclusions:

• The synergistic strategy of heteroatom doping and matrix-assisted synthesis effectively enhances RTP properties of carbon dots.
• The developed N-CDs@Na2B4O7 composite shows great potential for advanced applications like multi-level information encryption due to its tunable colors and long RTP lifetimes.