A theoretical study on superalkali-doped nanocages: unique inorganic electrides with high stability, deep-ultraviolet transparency, and a considerable nonlinear optical response

Abstract

By doping an Al₁₂N₁₂ nanocage with superalkali Li₃O, a series of Li₃O@Al₁₂N₁₂ compounds were theoretically designed and investigated for the first time. Computational results reveal that these species contain diffuse excess electrons, and thus can be regarded as inorganic electrides of a new type. As expected, these proposed electrides possess considerable first hyperpolarizabilities (β₀) up to 1.86 × 10⁷ au. In particular, the lowest-energy Li₃O@Al₁₂N₁₂ exhibits high stability and excellent deep-ultraviolet transparency. Moreover, the effects of superalkali and nanocage subunits on the NLO responses of M₃O@Al₁₂N₁₂ (M = Li, Na, K) and Li₃O@X₁₂Y₁₂ (X = B, Al; Y = N, P) are systemically investigated. Results show that the respective substitution of Na₃O and B₁₂P₁₂ for Li₃O and Al₁₂N₁₂ can bring a larger β₀ for such electrides. This study may be significant in terms of providing an effective strategy to design thermally stable inorganic electrides as potential high-performance NLO molecules.