The semiempirical (PM3) and DFT quantum mechanical methods were used to investigate the theoretical degradation of Indigo dye. The chemical reactivity of the Indigo dye was evaluated by comparing the potential energy stability of the mean bonds. Seven transition states were suggested and studied to estimate the actually starting step of the degradation reaction. The bond length and bond angle calculations indicate that the best active site in the Indigo dye molecule is at C10=C11. The most possible transition states are examined for all suggested paths of Indigo dye degradation predicated on zero-point energy and imaginary frequency. The first starting step of the reaction mechanism is proposed. The change in enthalpy, Gibbs free energy and change in entropy of the overall reaction are equal to -548268.223 kcal/mol, 30831.951 kcal/mol and 48.552 cal/mol.deg, respectively. The activation energy is 46176.405 kcal/mol. The reaction rate is equal to .

In the present study, density function theory (DFT) tool is used to compute structural, electronic and optical properties for hexagonal-boron-nitride (h-BN) nanosheet, perfect and defected (one carbon atom remove) graphene (G)/boron-nitride nanoisland. The basis set 6-31G is utilizing in a present study with hybrid function (B3LYP). Relaxation calculation is showing that all bond length between atoms are agreement with theoretical and experimental measurements, also the surface of all systems was remain in plane form. Energy gap calculation shows that a h-BN nanosheet has insulator nature. Doping h-BN by carbon (C) and defected (by remove one carbon atom) the energy gap is modifying and reduce from (6.006) to (3.464 and 1.569) eV, respectively. In the other hand, doped and defected mechanism enhance the conductivity of h-BN nanosheet. UV-Visible calculation is showing that h-BN absorbing in the ultra-violet region, doped and defected nanoisland were absorbed light in the visible region of electromagnetic radiation and shifted to long wavelength (Low energy). Fourier transformation-infrared radiation (FT-IR) calculations are showing that all active group are appearing like (C-C), (C-B), (C-N), (B-H) and (N-H) and approximately agreement with experimental measurements. Light harvesting efficiency (LHE) calculation is concluding that h-BN/G nanoisland have high ability to harvest light compared with h-BN nanosheet and defected h-BN/G nanoisland. Results show that higher occupied molecular orbital (HOMO) is being distributed above minimum conduction band (CBM) of titanium dioxide (TiO2), and lower unoccupied molecular orbital (LUMO) is being populate below iodine/ tri-iodine (I/I₃) electrolyte. Meanwhile, all nanostructure is having ability to generate pair electron-hole. Finally, results show that the measurements are indicating that it is possible to apply the composites under study in the field of photonic devices especially in solar cell field.

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 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).