Triphenylamine derivatives and the lithium-ion capture of [3.3]cyclophane used in organic dye-sensitized solar cells

Four novel organic dyes (H-1, H-2, H-3, H-4) containing phenyl-thiophenyl-thiophenyl as a bridge unit were synthesized and effectively used for the fabrication of dye-sensitized solar cells (DSSCs). In both compounds, a triarylamine moiety and cyanoacrylic acid function as an electron donor and an electron acceptor, respectively. H-1 and H-3 exhibited high interaction between lithium ions and [3.3]paracyclophane, resulting in low charge recombination and high open-circuit voltage (V_oc). When deoxycholic acid was used as a coadsorbent, the optimal device performance was observed in H-3, involving a short-circuit current of 16.96 mA cm⁻², a V_oc of 705 mV, and a fill factor of 0.64, which correspond to an overall conversion efficiency of 7.55%. Photophysical properties were analyzed using a time-dependent density functional theory model and the B3LYP functional. Furthermore, the electronic characteristics of the DSSCs were determined using electrochemical impedance spectroscopy and controlled intensity-modulated photospectroscopy.