First-Principles Study of Structural, Electronic, Thermal, and Optical Properties of Quasi-2D C 2 N 2 O Using GGA and HSE06

DFT and AIMD are used to investigate the structural, stability, electronic, thermal, and optical properties of the quasi-2D C 2 N 2 O structure. The structure exhibits thermal and energy stability, signifying robustness under ambient conditions, however dynamical instability is observed. The electronic structure investigation reveals that C 2 N 2 O displays semiconducting properties with a moderate indirect band gap resulting from the hybridisation of p-orbitals of N, C, and O atoms, with band gap values of 2.3 eV (GGA) and 3.93 eV (HSE06). The optical properties, including the dielectric function, optical conductivity, and refractive index, are thoroughly analyzed to clarify the electronic transitions. The material exhibits considerable optical absorption in the visible and ultraviolet spectrum, with notable anisotropy between in-plane and out-of-plane polarizations. Furthermore, plasmon resonance occurs at around 14.3 eV, relating to the collective oscillations of charge carriers. The thermal properties indicate a heat capacity of around 382 J/mol.K at 300 K, which is close to and slightly above the standard Dulong-Petit limit for this structure, indicating near-complete excitation of lattice vibrational modes at room temperature. The lattice thermal conductivity is extremely low, reaching approximately 0.017 W/m.K at 300 K, primarily attributed to significant phonon scattering, evidenced by a scattering rate of roughly 3.2 1/ps in the phonon frequency ranges. The findings demonstrate that the C 2 N 2 O structure maintains structural stability while allowing for tunable electronic, optical, and thermal properties, making it a promising candidate for nanoscale optoelectronic and thermal control applications.