Computational insights into bis-N,N-dimethylaniline based D-π-A photosensitizers bearing divergent-type of π-linkers for DSSCs

Abstract

In this study, theoretically designed D-π-A derivatives containing different π-subunits as linkers were investigated to enlighten their potential applicability in photovoltaic applications. For this aim, we first focused on clarifying the effect of tailored π-linker scaffolds on the frontier orbital energies of the investigated photosensitizers. In the concomitant step, global descriptors, TiO₂ adsorption, maximum absorbance wavelength, light-harvesting efficiency (LHE), energy conversion efficiency (η), short circuit current density (J_SC), open circuit photovoltage (V_OC), fill factor (FF), and reorganization energy (λ_e, λ_h, λ_T) values, electron density differentiation maps (EDDM), transition density matrices (TDM), fragmental contributions on electron-hole overlap were investigated in detail. Based on the trend of the calculated properties, 2,3-dimethylthieno [3,4-b]pyrazine (D-Ɛ₃-δ_n-A; n = 1-3) and 5-isobutyl-10,11-dimethyl-10,11-dihydro-5H-pyrrolo [3,4-e]thieno [2',3':4,5]pyrrolo [3,2-g]thieno [3,2-b]indole (D-Ɛ₆-δ_n-A; n = 1-3) bearing molecules were identified as the best-suited and improved dye candidates for DSSC applications. Following the prediction of photovoltaic properties for the pristine dye molecules, our consecutive efforts have contributed to a similar calculation protocol comprising DFT and subsequent TD-DFT computations for the D-Ɛ_n-δ_n-A@Ti₅O₁₀ clusters to elucidate the interaction of the investigated photosensitizers with the semiconductor layer (TiO₂).

Keywords: Bis-N,N-dimethylaniline; D-π-A; DFT; DSSC; Dithienothiophene; TD-DFT; Thienothiophene.