Self-Assembled Organic Single-Crystals Embedded with Dual-Color Phosphorescent Carbon Dots for Aqueous RTP Materials

Area of Science:

• Materials Science
• Photophysics
• Nanotechnology

Background:

• Aqueous room-temperature phosphorescent (RTP) materials are crucial for resisting quenching in aqueous and oxygen-rich conditions.
• Developing novel RTP materials with enhanced stability and unique optical properties is an active research area.
• Potential applications in advanced information encryption technologies drive the demand for such materials.

Purpose of the Study:

• To synthesize and characterize a novel aqueous RTP material, S-CDs@SA composite.
• To investigate the photoluminescent properties, including fluorescence and phosphorescence, of the S-CDs@SA composite.
• To explore the potential applications of the S-CDs@SA composite in information encryption.

Main Methods:

• One-pot hydrothermal synthesis of S-CDs@SA composite using sulfanilic acid (SA) and cysteamine hydrochloride.
• Characterization of the material's structure and composition.
• Photoluminescence spectroscopy to analyze fluorescence and phosphorescence emission spectra, quantum yield, and afterglow lifetime.
• Temperature-dependent luminescence studies to investigate thermochromic effects.

Main Results:

• Successful preparation of S-CDs@SA composite, comprising SA single crystals embedded with sulfur-doped carbon dots (S-CDs).
• The material exhibits blue fluorescence (476 nm) under 365 nm excitation and strong yellow phosphorescence (586 nm) with a weak shoulder (495 nm) after excitation stops.
• Achieved a phosphorescence quantum yield of 9% and an afterglow lifetime of 827.5 ms, with stable luminescence in aqueous environments.
• Demonstrated temperature-dependent phosphorescence color shift (yellow to green) at low (77 K) and high (388 K) temperatures, with water suppressing the high-temperature effect.

Conclusions:

• The S-CDs@SA composite is a promising aqueous RTP material with excellent stability and unique temperature-dependent optical properties.
• The observed phosphorescence characteristics suggest significant potential for applications in advanced information encryption technologies.
• Further research into optimizing synthesis and exploring diverse encryption applications is warranted.