Theoretical Prediction of Cr-Doped Antimonene as an Efficient Optoelectronic Material: A Hybrid Functional Study

The electronic and optical absorption properties of antimonene doped with four Cr contents (1.4%, 3.1%, 5.6%, and 12.5%) have been systematically investigated using the Heyd–Scuseria–Ernzerhof hybrid functional method. It has been found that the spin-down impurity bands (induced by Cr incorporation) mix with the valence band, and broaden to significantly reduce the band gap with the increasing Cr content. The spin-up impurity bands appear in the form of intermediate states, and become dispersive with the increasing Cr content, which is expected to effectively dissociate the electron–hole pairs to relay the excited valence electrons into the conduction band. Especially, the 12.5% Cr content narrows the spin-down band gap to 1.25 eV (which extends the photoabsorption wavelength into the near-infrared range), and simultaneously enhances the electron mobility of the spin-up impurity band to 138 cm²/Vs (which is helpful for separating and collecting the photo-excited carriers), remarkably promoting the optical absorption. The promotion in photoabsorption further gets confirmation from the calculated optical absorption spectra of the virgin and doped monolayers, suggesting that antimonene with 12.5% Cr doping is an efficient optoelectronic material. Also, the thermodynamic and kinetic stabilities of the Cr dopant in this 2D material have been well addressed. This work provides fundamental guidance for broadening the functional applications of antimonene in optoelectronics via effective doping.