Cyclohexadienone core 3,6-di-tert-butylcarbazole decorated triazole bridged dendrimers: synthesis, photophysical and electrochemical properties and application as an additive in dye-sensitized solar cells

Cyclohexadienone core 3,6-di-tert-butylcarbazole decorated triazole bridged dendrimers are synthesised up to the second generation using click chemistry via a convergent approach. The molar extinction coefficient and the intensity of the emission band increase with an increase in the dendrimer generation. The HOMO-LUMO energy level and the energy gap E_g obtained from photophysical and electrochemical parameters coincide with the results obtained from DFT calculations. The higher generation dendrimer 3 (G₂) shows a higher V_oc value and an increased efficiency of 9.01% when used as additive in DSSCs compared to the lower generation dendrimers 2 (G₁) and 1 (G₀) under 100 mW cm⁻² illumination. Further, Nyquist plots obtained from electrochemical impedance measurements also show that the higher generation dendrimer G₂ provides an increased number of charge transport pathways, which enhances interfacial electron transport and reduces the recombination dynamics.