Browsing by Author "Seriani, Nicola"

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Investigation of optoelectronic properties of triphenylamine-based dyes featuring heterocyclic anchoring groups for DSSCs’ applications: a theoretical study
(Springer Nature Switzerland AG., 2020-08-05) Deogratias, Geradius; Al-Qurashi, Ohoud S.; Wazzan, Nuha; Seriani, Nicola; Pogrebnaya, Tatiana P.; Pogrebnoi, Alexander M.
Design and synthesis of new potent sensitizers are of interest for realization of high-efficiency Dye Sensitized Solar Cells (DSSCs). Modification of the triphenylamine-based dyes by introducing suitable anchoring groups aimed at improvement of optoelectronic properties is attempted in our work. The molecular structure, molecular orbitals and energies, electronic absorption spectra, free energies of electron injection and dye regeneration, chemical reactivity parameters and adsorption to TiO2 semiconductor have been reported. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to obtain the reported properties. The results reveal superior optical, electronic properties, chemical reactivity parameters and adsorption energies for the investigated dyes. The findings evince that the dyes featuring heterocyclic anchoring groups could be potential candidates for DSSCs’ applications; the new materials are worthy of being investigated experimentally.
Methylammonium tin iodide perovskite: structural, electronic and thermodynamic properties by a DFT study with different exchange–correlation functionals
(Springer Nature Switzerland AG., 2020-03-20) Paschal, Catherine; Pogrebnoi, Alexander M.; Pogrebnaya, Tatiana P.; Seriani, Nicola
Lead-free perovskites have drawn much attention of researchers in the field of electronics and photovoltaics due to the toxicity issue of the lead halide perovskites. The methylammonium tin iodide CH3NH3SnI3 amongst others has become a viable alternative due to its eco-friendliness, as well as narrower bandgap and its wider visible absorption spectrum. In this study different theoretical approaches were employed in investigating the structural, electronic and thermodynamic properties of the orthorhombic phase (O-phase) of the CH3NH3SnI3 perovskite. By using the first-principle calculations with the density functional theory, a direct bandgap was determined at gamma symmetry points with three exchange–correlation functionals: PBE 1.12 eV, PBEsol 0.98 eV, and LDA 0.46 eV. Based on the comparison of lattice constants and bandgaps with the experimental values, the best performance resulted from PBE. The decomposition of the CH3NH3SnI3 perovskite into solid state products, CH3NH3I and SnI2, was considered; the enthalpy of the reaction ΔrH° (0 K) = 37 kJ mol−1 and enthalpy of formation of the O-phase perovskite ΔfH° (CH3NH3SnI3, 0 K) = − 390 kJ mol−1 were evaluated, indicating the stability of the O-phase CH3NH3SnI3 at low temperature, in agreement with experimental findings.
Tuning optoelectronic properties of triphenylamine based dyes through variation of pi-conjugated units and anchoring groups: A DFT/TD-DFT investigation.
(Elsevier Inc., 2020-01-01) Deogratias, Geradius; Seriani, Nicola; Pogrebnaya, Tatiana; Pogrebnoi, Alexander
Dye-sensitized solar cells (DSSCs) have attracted widespread attention due to their unique features. In the present work, molecular engineered triphenylamine based dyes featuring donor-bridge-acceptor architecture have been considered and investigated for suitable properties for DSSCs applications. Hydantoin anchoring group has been introduced replacing the commonly used cyanoacrylic acid to improve the long-term stability of the device. Results on the effects of varied anchoring groups and pi-spacers have been interpreted from the viewpoint of DFT/TD-DFT calculations. Designed sensitizers exhibit suitable light-harvesting efficiencies, excited-state lifetimes, electron injection and regeneration abilities. Red-shifted electronic spectra are observed for three hydantoin dyes compared to others in the same family. Further analysis of chemical descriptors and observation from full-electron donor-acceptor map reveal that the three dyes among nine are potential materials with promising properties towards improving DSSCs performance.