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 was calculated to 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.

In this study, density functional theory (DFT) and time-dependent DFT (TD-DFT) methods were employed to investigate the geometrical, electronic, optical, and photovoltaic properties of graphene (G), silicon carbide (SiC), and graphene/hexagonal boron nitride (G/h-BN) nanostructures. Dimethyl sulfoxide (DMSO) was used as a solvent to enhance the electronic behavior of the systems. Key photovoltaic parameters such as open-circuit voltage (VOC), light harvesting efficiency (LHE), and the free energies of electron injection and regeneration were evaluated. Results revealed efficient electron injection from G, SiC, and G/h-BN into the conduction band of TiO₂. The HOMO levels of G and SiC were found above the I⁻/I₃⁻ redox potential, indicating potential limitations in electron regeneration; however, this was mitigated upon dissolution in DMSO. Additionally, DMSO improved optical absorption by red-shifting the UV–visible spectra. Overall, isolated G/h-BN and the DMSO-dissolved nanostructures show promise as sensitizers in dye-sensitized solar cells (DSSCs).

The structural and vibrational properties of ZnnSen (n=1,3,7,13) nanostructures have been investigated using the Gaussian 09 program, density functional theory and time-dependent density functional theory at the B3LYP level with 6–311G basis functions. The structural properties showed that the rebuilding in surface atoms deviated many bonds from their ideal length, the Zn-Se bond length decreased with the increase in the size of nanostructures and converged to the experimental value. Quantum confinement effect diminution was observed with the growing size of the nanostructures; hence, the energy gap converged to the experimental value of 2.7 eV. Moreover, the binding energy increased with the increase of the structure size, such that wurtziod2c (Zn13Se13) is more stable than smaller structures. The vibrational properties results indicated that the experimental longitudinal optical mode (LO mode) is situated between bare and hydrogen passivated LO modes and very near to the bare case, this gave a good agreement with experimental findings. The presence of hydrogen atoms at the surface caused a several times decrease in vibrational force constant in comparison to the bare case. The IR spectrum for wurtzoid and HP wurtzoid were investigated. The optical edge in UV-Vis spectra of wurtzoid reduced from 4.5 eV to 4.2 eV of wurtzoid2c due to the increase in the size of the nanostructure, while the maximum peak for wurtzoid at 2.88 eV increased to 3.06 eV for wurtzoid2c showing a clear blue shift. These results leads to wide applications in fields such as photoelectronic devices, lasers, sensors, and LEDs.

The chlorophyll molecule is considered a low-cost material, easy to synthesize, and easily extracted from plant leaves. It exhibits high chemical stability, structural flexibility, and high absorbance ability at the visible range of electromagnetic radiation. In this work, the geometrical, electronic, and optical properties of pure, dissolved, and doped chlorophyll (C1) natural organic dye were computed by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The solvents considered include water (H₂O), acetone (C₂H₆O), dichloromethane (CH₂Cl₂), chloroform (CH₃Cl), and dimethyl-sulfoxide (DMSO) (C₂H₆OS). The solar photovoltaic parameters, such as light-harvesting efficiency (LHE), oscillation strength (f), free energy of electron injection (${\Delta \mathrm{G}}_{\mathrm{I}\mathrm{n}\mathrm{j}.}$) and regeneration (${\Delta \mathrm{G}}_{\mathrm{R}\mathrm{e}\mathrm{g}.}$), open-circuit voltaic (V_OC), and efficiency ($\eta$), were also investigated. The evaluated energy gap slightly shifted from 1.920 eV to 1.980 eV based on the solvent polarity, while the UV-Visible absorption spectrum red-shifted from 422.3 nm to 439.8 nm, improving the overall efficiency up to 21.5% in DMSO solvent. The (LHE) and (${\Delta \mathrm{G}}_{\mathrm{I}\mathrm{n}\mathrm{j}.}$) properties regarding Cl molecules improved up to 69.1% and −1.384 eV when dissolved in chloroform and DMSO solvents, respectively. Doping C1 molecule via metal transition atoms such as zinc (Zn), nickel (Ni) and copper (Cu) further modified the optical and photovoltaic performance. Doped C1 molecule via Cu atom shows the best photonic results, including the highest open-circuit voltage (V_oc) and conversion efficiency ($\mathrm{Ƞ}$), while the Ni-doped C1 dye displays the longest lifetime, 1.699 µs, and the highest electronic coupling constant, 1.975 eV; thus, it has the superior photovoltaic performance. These results demonstrate that both solvents and transition metal atom modification significantly improve C1 performance, making metal-doped C1 a promising low-cost and eco-friendly sensitizer for dye-sensitized solar cells (DSSCs).