Analysis of electronic, raman and UV-vis spectra for Zn11Se11, Zn11S11, and ternary alloys Zn11SnSe11-n(n= 1-11) a DFT/TDDFT study

Abstract

Zn11Se11, Zn11S11, and ternary alloys from Zn11SnSe11-n (n = 1 - 11), with cubic structures represented by nanostructures called tetramantane, have been studied theoretically by investigating the electronic properties, Raman and UV-vis spectra. LUMO and HOMO levels were observed to change with the number of the sulfur atoms. The (HOMO - LUMO) gap for Zn11Se11 (2.377205eV) increased with the sulfur atoms. Zn11S8Se3 have an energy gap (3.061305eV) less than others ternary alloys. The calculated energy gap of Zn11S11 (3.597374eV) is in a high agreement with experimental value (3.6 eV). Raman spectra for ternary alloys Zn11SnSe11-n content peaks result from the connection of (Zn11Se11+Zn11S11) peaks, Zn11Se11 has peak at 260.42 cm-1 shifts from the experimental value by a small deviasion which is produced due to the confinement effect. UV-vis spectra for ternary alloys shifted to a higher energy level with the increase in the number of sulfur atoms and dramatically close to Zn11S11 UV-vis spectrum except Zn11S8Se3 has λmax at 342 nm. These nanostructures are suitable to be used in different applications such as lenses, photoelectronic devices, solar energy, and biosensors. DFT/TDDFT at the B3LYP level with SDD basis functions is used. All the calculations are completed using the Gaussian 09 program.