Structural, electrical, optical, and DFT studies of phenothiazine-based D–π–A frameworks for dye-sensitized solar cell applications

The phenothiazine-derivative dyes have been designed using phenothiazine group (donor part), thienothiophene (spacer part), and different acid groups (electron-acceptor part). Time-dependent density functional theory (TD-DFT) and density functional theory (DFT) have been used to study the electronic and optical properties of the designed dyes (B1–B10). The dye B8 has planar conformations with a dihedral angle of 0.15° which indicates electron delocalization over the molecules. The dye B6 has a low chemical hardness value. The energy gap, ionization potential, electron affinity, and chemical hardness of the dyes have been computed, and efficiency has been analyzed. The B8 dye sensitizer has a higher dipole moment (5.324 Debye) compared to the other sensitizers, due to the presence of two cyano groups in the acceptor parts. The NLO characteristics have been determined based on the polarizability and first-order hyperpolarizability values of the designed dyes. The LHE values of dye molecules ranged from 0.75 to 0.89 eV. The dye sensitizers B6 and B8 have high efficient values compared with other designed dyes.