Regulating the Structure and Optical Properties of Graphitic Carbon Nitride by Tuning Edge Aromatic Functional Groups

Graphite-phase carbon nitride (g-CN) shows significant potential for optoelectronic applications due to its low cost and high thermal stability. However, its utilization in light-emitting devices is hindered by a low photoluminescence quantum yield (PLQY) and a limited emission wavelength. This paper presents the synthesis of phenyl-, biphenyl-, and <i>p</i>-terphenyl-modified g-CN via direct thermal polymerization, with the aim of enhancing optical properties and elucidating underlying luminescence mechanisms. Intriguingly, the elongation of aromatic rings results in a notable red shift of their emission peaks. Specifically, the PLQY of <i>p</i>-terphenyl-modified g-CN reaches up to 40.2%. Matching with blue light-emitting diode (LED) chips, <i>p</i>-terphenyl-modified g-CN was used as a phosphor to fabricate white LEDs, achieving chromaticity coordinates of (0.3443, 0.3389), a color-rendering index of 95, and a luminous efficiency of 24.03 lm/W. This study introduces a new approach for regulating the luminescence efficiency and emission wavelength of g-CN materials, offering significant potential for advanced optoelectronic applications.