Tweaking the Electronic and Optical Properties of α-MoO3 by Sulphur and Selenium Doping – a Density Functional Theory Study

Abstract

First-principles calculations were carried out to understand how anionic isovalent-atom doping affects the electronic structures and optical properties of α-MoO3. The effects of the sulphur and selenium doping at the three unique oxygen sites (Ot, Oa, and Ot) of α-MoO3 were examined. We found that the valence p orbitals of Sulphur/Selenium dopant atoms give rise to impurity bands above the valence band maximum in the band structure of α-MoO3. The number of impurity bands in the doped material depends on the specific doping sites and the local chemical environment of the dopants in MoO3. The impurity bands give rise to the enhanced optical absorptions of the S- and Se-doped MoO3 in the visible and infrared regions. At low local doping concentration, the effects of the dopant sites on the electronic structure of the material are additive, so increasing the doping concentration will enhance the optical absorption properties of the material in the visible and infrared regions. Further increasing the doping concentration will result in a larger gap between the maximum edge of impurity bands and the conduction band minimum, and will undermine the optical absorption in the visible and infrared region. Such effects are caused by the local geometry change at the high local doping concentration with the dopants displaced from the original O sites, so the resulting impurity bands are no long the superpositions of the impurity bands of each individual on-site dopant atom. Switching from S-doping to Se-doping decreases the gap between the maximum edge of the impurity bands and conduction band minimum, and leads to the optical absorption edge red-shifting further into the visible and infrared regions.

MXenes for Plasmonic Photodetection

“…On a side note, it has not escaped our notice to consider any possible photoabsorption by the oxidized Mo species (see Figure i). However, such Mo oxidized species (e.g., MoO 3 and/or Mo 4 O 11 ) are known to have wide a band gap of ≈3.2 eV or even larger, which rules out the possibility of their contribution in the visible photoresponse of our Mo 2 CT x thin films.…”

Charge Storage Behaviour of α‐MoO3 in Aqueous Electrolytes – Effect of Charge Density of Electrolyte Cations

“…The optimised lattice vectors, a = 11.84 Å, b = 14.21 Å, c = 11.12 Å, and MoÀ O bond lengths, 1.70 Å, and 1.95 Å were found in good agreement with the literature. [46] After obtaining the optimised MoO 3 structure, metal cations were introduced at different inequivalent binding sites within the lattice of the bulk structure. Complete structural optimisation was performed, and the binding energies (E b ) of MÀ MoO 3 (M: Na, Mg or Al) were calculated.…”

Advanced Strategies to Improve Performances of Molybdenum-Based Gas Sensors

“…This proves that there is an excellent opportunity for further exploration of this strategy. In addition, elemental doping can also be realized with nonmetal doping such as nitrogen, sulfur, selenium, and carbon [128][129][130][131][132]. Nonmetal doping has been reported to alter the electronic structure, reduce the bandgap, increase the amount of oxygen vacancy, increase the gas adsorption capacity, and induce bipolar electrical transport [128,133].…”