Exfoliation energy, quasiparticle band structure, and excitonic properties of selenium and tellurium atomic chains

Abstract

Effects that are not captured by the generalized-gradient density-functional theory play a prominent effect on the structural binding, and on the electronic and optical properties of reduceddimensional and weakly-bound materials. Here, we report the exfoliation energy of selenium and tellurium atomic chains with non-empirical van der Waals corrections, and their electronic and optical properties with the GW and Bethe-Salpeter formalisms. The exfoliation energy is found to be within 0.547 to 0.719 eV/u.c. for the selenium atomic chain, and 0.737 to 0.926 eV/u.c. for the tellurium atomic chain (u.c. stands for unit cell), depending on the approximation for the van der Waals interaction and the numerical tool chosen. The GW electronic bandgap turned out to be 5. 22-5.47 (4.44-4.59) eV for the Se (Te) atomic chains, with the lowest bound obtained with the Godby-Needs (GB), and the upper bound to the Hybertsen-Louie (HL) plasmon-pole models (PPMs). The binding energy of the ground-state excitonic state ranges between 2.69 to 2.72 eV for selenium chains within the HL and GB PPM, respectively, and turned out to be 2.35 eV for tellurium chains with both approximations. The ground state excitonic wave function is localized within 50Å along the axis for both types of atomic chains, and its energy lies within the visible spectrum: blue [2.50(GN)-2.78(HL) eV] for selenium, and yellow-green [2.09(GN)-2.28(HL) eV] for tellurium, which could be useful for LED applications in the visible spectrum.

Dependence of excited-state properties of tellurium on dimensionality: From bulk to two dimensions to one dimensions

“…Studies on many-electron effects of similar structures, such as 1D Se, have been reported recently. [55] The DFT-calculated and quasiparticle energy band structures of the isolated chain Te without SOC are plotted in Fig. 4(a).…”

“…The e-h binding energy of the lowest-energy E 1 exciton is about 2.40 eV, which is comparable with that of the chain Se (2.77 eV) and significantly surpasses that (0.67 eV) in monolayer Te. [55] A very large exciton binding energy of 3.5 eV was calculated in the BN chain. [9] Our further analysis shows that the E 1 exciton is from the interband transitions between the first, second, and third highest valence bands and the first…”

Solid-State Fluorescent Selenium Quantum Dots by a Solvothermal-Assisted Sol–Gel Route for Curcumin Sensing

“…According to values reported in the literature, trigonal selenium exhibits a band gap energy value of 2 eV. 13 , 57 , 58 Although a higher energy gap is expected in quantum dots due to confinement effects, a slight decrease in band gap is observed in t-Se QDs. This can be attributed to the presence of surface states and traps.…”

Temperature, strain and charge mediated multiple and dynamical phase changes of selenium and tellurium

“…Also, composite materials constituted by a dielectric material sandwiched between two t-phases can offer functionalities for tunneling devices. As a final remark, 3D crystals, multilayer, bilayer and monolayer, and 1D chain structures [58][59][60][61] of Se and Te elements can reconstruct to form diverse structures with unusual properties under strain, thermal and optical excitations, excess charge and electric field.…”