Novel cobalt redox materials admitted in natrosol polymer with a thiophene based additive as a gel polymer electrolyte to tune up the efficiency of dye sensitized solar cells

Synthesis of novel cobalt redox pairs such as Co^2+/3+[bnbip]₂, Co^2+/3+[npbi]_3, Co^2+/3+[b(ttb)bip]₂ and unknown organic additive integrated into a new natrosol polymer host act as an polymer gel electrolytes in DSSC. The newly synthesized ligands and organic additive (BNBIT) was characterized by ¹H, ¹³C NMR and HRMS spectroscopy and complexes were confirmed by UV–Visible, FTIR and ESI-MS spectrum. Electrochemical analysis was determined for all new redox pairs in that Co^2+/3+[bnbip]₂ shows positive E_1/2value 0.51 V V NHE and higher formal potential 0.55 V which leads a way to increase in open circuit voltage of DSSC. The new natrosol polymer gel electrolytes was characterized by using UV–Visible, FTIR, DSC, XRD, impedance spectrum and I–V curve. The conductivity increases up to 7.14×10⁻⁴Scm⁻¹ for natrosol polymer gel electrolyte with a novel organic additive and stable Co^2+/3+[bnbip]₂ redox pair. The new organic additive plays a vital role in DSSC device which shields the Co³⁺ ions of the redox pair in gel electrolytes and interaction with TiO₂ surface that made shift in quasi Fermi level of TiO₂ which suppresses the recombination processes. The new natrosol polymer gel electrolytes with novel cobalt redox pairs and thiophene based organic additive that enhances the efficiency up to 4.5% under light illumination of 100 mW/cm² with a better stability. A increase in photocurrent due to BNBIT organic additive and the best E_1/2 value of Co^2+/3+[bnbip]₂ mediator which made shift in (E_F,n) quasi Fermi level of TiO₂ that mitigate the recombination process in DSSCs. The interfacial studies in DSSCs were focused via EIS to elucidate the charge transport mechanisms at the interfaces of photoelectrodes and electrolyte medium of the devices.