TDDFT Studies on Sheet Size-Dependency of Optoelectronic Properties of 2D Silicon Doped with Alkali Metals

This work investigates the effect of alkali metals (Li, Na, and K) doping on silicene sheets (2D silicon) by using Time-Dependent Density Functional Theory (TDDFT). This includes Si ₁₃ H ₂₂ , Si ₁₉ H ₃₀ , Si ₅₄ H ₇₄ , and Si ₁₀₄ H ₁₃₄ silicene sheets. The results show some variation in the IR and UV-Vis spectrums as the sheet size change, with the largest structure showing an onset of absorption in the visible spectrum. Also, the results show that excitation energy decreases significantly by 29% as the number of atoms increases from Si ₁₃ H ₂₂ to Si ₁₀₄ H ₁₃₄ . Also, this work investigates the doping effect of alkali metals (Li, Na, and K) on the silicene sheets. The doped structures showed a dipole moment as high as approximately 10 Debye. The doped structures show a significant increase in optical absorption in the visible spectrum, as well as the potential for high reactivity.