Highly luminescent cyanuric acid-supported carbon nitride hybrids for multi-color light-emitting diodes and solid-state fluorescent sensing

Abstract

The development of photoluminescent (PL) properties in graphitic carbon nitride (g-C₃N₄) has been limited by their short PL wavelength. Herein, we synthesized tunable multi-color emissive cyanuric acid-supported g-C₃N₄ materials (CNS) via a one-pot microwave-assisted method using urea and thiophene-3,4-dicarboxylic acid (TDC) as starting materials. By varying the TDC amount, the solid-state emissive color of CNS samples can be manipulated from blue to orange-red. The incorporation of thiophene ring into the g-C₃N₄ framework during microwave synthesis enlarges the π-conjugation system, narrowing the band gap from 3.94 to 1.91 eV, as verified by the DFT calculations. The hydrogen-bond networks from cyanuric acid-supported g-C₃N₄ improves the framework crystallinity, enabling the high emission efficiency (quantum yields up to 0.27). These properties make CNS highly suitable for multi-color light-emitting diodes (LED) applications, particularly in WLEDs with chromaticity coordinates (0.341, 0.359). Additionally, this study pioneers the use of CNS as a solid-state fluorescent probe for Fe³⁺, expanding its optical application fields. Our findings suggest significant potential for CNS_x materials in advanced LED lighting solutions, with broad applicability in illumination, information encryption, and anti-counterfeiting.