Band Structure Engineering of MXenes for Low-Loss Visible Epsilon-Near-Zero Properties by First-Principles Calculation

Epsilon-near-zero (ENZ) photonics, which exhibit extraordinary capabilities in terms of controlling light-matter interactions, have been attracting increased interest in recent years. However, several challenges still lie ahead, such as large optical loss and the rarity of ENZ candidates, especially in the visible range. Here, by first-principles calculations, this work proposes dozens of MXenes with promising plasmonic properties that could be potential ENZ candidates with very low loss in the visible range by band structure engineering. Because of the special electronic structures of these MXenes, they all possess quite large screened plasmonic frequencies: omega p/epsilon infinity\[{{\bm{\omega }}_{\bf p}}{\rm{/}}\sqrt {{{\bm{\varepsilon }}_{\bm{\infty }}}} \], but less than the interband transition onsets, which cause the ENZ properties in these MXenes to appear in the visible range with very low loss (epsilon(2) less than 0.2) by eliminating the interband transition loss at the ENZ frequencies. Furthermore, it is also demonstrated that the ENZ properties in MXenes, including the ENZ frequency and loss, can be effectively tuned upon surface modifications, such as -Cl and -OH. These outstanding ENZ properties, including tunablity and low-loss, make these MXenes great for potential applications in ENZ photonics, especially in the visible-light range.

Automated summary

Epsilon-near-zero (ENZ) photonics, with great capabilities in controlling light-matter interactions, have gained increasing interest. However, challenges remain, including high optical loss and limited availability of ENZ candidates in the visible range. This study proposes numerous MXenes with promising plasmonic properties as potential ENZ candidates in the visible range, achieved through band structure engineering and low interband transition loss. The ENZ properties, including frequency and loss, can be effectively tuned through surface modifications, making these MXenes highly suitable for ENZ photonics applications in the visible-light range.