In this article, we report two indole-based metal-free organic dyes In-T-2C (3-(5-(3-((2-carboxy-2-cyanovinyl)-1-pentyl-1H-indol-5-yl)thiophen-2-yl)-2-isocyanoacrylic acid) and In-B-C (2-cyano-3-(5-(4-cyanophenyl)-1-pentyl-1H-indol-3-yl)acrylic acid) with A-π-D-A architecture. The molecular structures of metal-free indole-based A-π-D-A organic dyes were elucidated using FT-IR, NMR, HRMS and single-crystal X-ray diffraction techniques. The present investigation examined the features of the synthesized dyes employing photophysical attributes, electrochemical traits and theoretical studies were executed to acquire a detailed comprehension of the geometry, electronic structure and absorption spectra of the synthesized dyes using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Additionally, dye-sensitized solar cells (DSSCs) were fabricated using newly synthesized dyes and examined their photovoltaic activity. Electrochemical impedance analysis (EIS) was performed to recognize the interfacial charge transfer in the DSSCs. The In-T-2C dye-based DSSC device exhibited an uppermost fill factor (FF) of 0.63, resulting in the uppermost open-circuit voltage (V OC) of 540.2 mV and highest efficiency (η) of 4.12% due to the highest short-circuit current density (J SC) of 12.1 mA cm-2 compared to the In-B-C dye (V OC = 497 mV, J SC = 1.07, FF = 0.70, η = 0.38%).
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