Comparative analysis of the substitutional and interstitial Li-,Na-doped, and Li\Na-Codoped Cu2O via density functional calculations

A comprehensive comparative study utilizing HSE06 and GGA density functional calculations was conducted to investigate the impact of Li and Na doping, as well as their co-doping, on the physical properties of cuprous oxide (Cu2O). This study examined three possible structures, including substitution of Li, Na, and Li/Na for Cu, and interstitial Li, Na, and Li/Na in both tetrahedral and octahedral sites. The results of the study revealed that the introduction of alkaline atoms leads to structural changes in Cu2O, and the degree of lattice parameter extension or compression varies across different doping sites. Additionally, the study provided an estimation of the enthalpies of formation for pure and doped-Cu2O, which is useful in understanding the stability of the systems. Notably, the study found that Li, Na, and Li/Na-doped-Cu2O were more readily formed in substitutional sites rather than in interstitial sites. The findings also indicate that substitutional doping and co-doping exhibit a large band gap while maintaining the properties of a p-type semiconductor, while interstitial doping and co-doping of Cu2O led to significant absorption enhancement and n-type conductivity characteristics. These results provide new insights into the structural and electronic properties of Cu2O, with the findings suggesting that interstitial doping of Li and Na could be a promising approach for improving the absorption of visible light in Cu2O-based solar cells, thus contributing to the development of more efficient and cost-effective photovoltaic devices.