New carbazole-based symmetric double D–A type chromophores for DSSC application: Impact of di-anchoring nature on photoelectrochemical processes

Abstract

Herein, we report the systematic molecular design, synthesis, and characterization of a new series of carbazole-based organic dyes with a symmetric double donor–acceptor configuration, bearing seven different acceptor units as potential photosensitizers. The new molecules consist of strong electron-donating carbazole twin molecules linked together by a linear alkyl chain (C<inf>5</inf>H<inf>10</inf>) and attached to the various anchoring units, viz. cyanoacetic acid (DCP<inf>1</inf>), rhodanine-3-acetic acid (DCP<inf>2</inf>), rhodanine (DCP<inf>3</inf>), 1,3-dimethylbarbituric acid (DCP<inf>4</inf>), barbituric acid (DCP<inf>5</inf>), 1,3-diethyl-2-thiobarbituric acid (DCP<inf>6</inf>), and 4-nitrophenyl acetonitrile (DCP<inf>7</inf>). We performed structural, photophysical, thermal, electrochemical, and theoretical studies to assess the role of the dual anchoring nature of the chromophores on photoelectrochemical processes and their suitability as photosensitizers. The optical results revealed that all the dyes display ?<inf>abs</inf> and ?<inf>emi</inf> in the 404–465 nm and 503–556 nm range, respectively, with a bandgap of 2.44–2.70 eV. Furthermore, we have successfully fabricated new Dye-Sensitized Solar Cells (DSSCs) using dyes DCP<inf>1–7</inf> as photosensitizers. Among them, DCP<inf>1</inf> achieved the power conversion efficiency (PCE) of ?2 % under standard AM 1.5 solar conditions. Also, electrochemical impedance spectroscopy (EIS) has been carried out to investigate electronic and ionic processes within the cell. Conclusively, these studies showcase the significant potential of carbazole twin molecules with various anchoring units in improving the overall performance of DSSCs. © 2025 Elsevier B.V.