A promising small-sized near-infrared absorbing zwitterionic dye for DSSC and NLO applications: DFT and TD-DFT approaches

Abstract

Herein we investigate the three quinoid zwitterionic dye sensitizers having donor-donor (4-dimethylaniline; ZIDM), donor-acceptor (4-dimethylaniline and 4-benzoic acid; ZIMCA), and acceptor-acceptor (4-benzoic acid; ZIDCA) that can be used in dye...

Exploration of 4-substituted thiophene-based azo dyes for dye-sensitized solar cells and non-linear optical materials: synthesis and an in silico approach

“…67 The higher values of the LUMO levels ensure that these dyes have a sufficient thermodynamic driving force for effective electron injection to the TiO 2 conduction band from the excited state of the dye. 67 Similarly, the HOMO levels of these dyes are more negative than the electrolyte's (iodide/triiodide, −4.8 eV) redox potential. The lower HOMO energies than the electrolytes’ redox potential suggest that dye regeneration will be efficient in these dyes from the dye cations.…”

“…The lower HOMO energies than the electrolytes' redox potential suggest that dye regeneration will be efficient in these dyes from the dye cations. 67 From ESI, † Fig. S1, it is evident that in the gas phase, when substituents were introduced at position 4 of the thiophene, the LUMO as well as HOMO energies of all dyes i.e., SR2 to SR9 compared to SR1 were destabilized.…”

“…For calculating these parameters, we have taken the help of Koopman's theorem approximation, according to which ionization potential and electron affinity are equivalent to the negative of the HOMO and LUMO energies, respectively. 67,73 In the above equations, negative energies of HOMO and LUMO are considered for getting the results of m and Z. G is a relatively recent DFT descriptor compared to Z, the third energy derivative representing the number of electrons in the system that illustrates the CT susceptibility. 74,75 For the calculation of G, the following formula is used:…”

“…The system's electron-poor center is represented by positive values in the MEP plots, whereas the most electron-dense area is displayed in red with negative values. [52][53][54]67 In all the cases, the TiO 2 cluster is surrounded by more negative energy and red surfaces, as seen in ESI, † Fig. S4.…”

“…Additionally, we have determined the adsorption energies (E ads ) following the equation below. 52,67,76,91…”