Design, synthesis, and photo physical characterization of Phenyl-(Benzo) phenothiazine-based organic photosensitizes for dye-sensitized solar cells

Abstract

The present study explores the synthesis and structural characterization of two novel organic photosensitizers. PBP-A and PBP-B, designed for DSSC applications. These sensitizers incorporate a thiophene core as a π-spacer, a phenyl-(benzo)phenothiazine moiety as the donor, and cyanoacrylic acid or rhodanine-3-acetic acid as the acceptor. The synthesized compounds’ (PBP-A and PBP-B) molecular structure were characterized using UV–Vis, NMR and FT-IR spectroscopy. The dyes' photophysical properties have been examined using UV–Vis spectroscopy, photocurrent density measurements, incident photon-to-current efficiency (IPCE), cyclic voltammetry (CV), and electrochemical impedance spectroscopy. PBP-A and PBP-B dye-sensitized solar cells (DSSCs) had short-circuit current densities (Jsc) of 11.21 mA/cm⁻² and 11.94 mA/cm⁻², resulting in power conversion efficiencies (η) of 5.63 % and 5.79 %, respectively. Furthermore, EIS analysis was used to assess the charge transfer characteristics at the electrode-electrolyte interface. The geometrical structures, optoelectronic properties, electron injection driving force (ΔG^inject), light-harvesting efficiency (LHE), excitation lifetime (τ), and other physicochemical characteristics were investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) computational approaches.