Investigating the efficacy of functionalized graphene oxide with polyhedral oligomeric silsesquioxane as an effective additive in sustainable ionic liquid-based electrolytes for dye-sensitized solar cells through experimental and DFT studies

Abstract

The focus of the study has been on the first-ever use of functionalized graphene oxide with polyhedral oligomeric silsesquioxane (FGO-POSS) as an effective additive to ionic liquid-based electrolytes in dye-sensitized solar cells (DSSCs). The electrolytes consisted of binary ionic liquids (ILs), 1-ethyl-3-methylimidazolium iodide (EMII), and 1-butyl-3-methylimidazolium iodide (BMII). Different concentrations of the efficient additive FGO-POSS, ranging from 0% to 1%, were incorporated into the electrolytes. Under highly controlled conditions, a series of reactions was conducted to synthesize FGO-POSS. By reacting graphene oxide (GO) with L-phenylalanine, initially, GO-L-phenylalanine was obtained. In the next phase, GO-L-Phenylalanine reacted with SSQ-[3-(2-Aminoethyl) amino] propyl-Heptaisobutyl substituted to modify its structure with polyhedral oligomeric silsesquioxane (POSS). The ILs, namely EMII, and BMII, were synthesized using the scientific methodologies detailed in the referenced articles. Furthermore, BMII was functionalized with CuI (BMICuI-2) through a specific procedure. Five types of electrolytes were prepared to be employed in DSSCs using prepared ILs and FGO-POSS, and their results were reported to show the electrical and gelatin features of these types of electrolytes. According to this study's findings, using FGO-POSS as an innovative and efficient additive in ILs-based environmentally sustainable nanocomposite electrolytes in an amount of 0.75 wt% increased the value of the short circuit current density (JSC) from 9.433 mA.cm−2 to 15.592 mA.cm−2, the open circuit voltage (VOC) from 0.738 V to 0.762 V, and the overall efficiency (η) increased from 4.965 to 8.303 %. The FGO-POSS and ILs, EMII, and BMICuI-2 boost electron transport and electrolyte conductivity, resulting in increased JSC, VOC, and η. Results of the density functional theory (DFT) calculation indicated that the adsorption of the FGO-POSS electrolyte additives on the TiO2 electrode surface produces midgap states in the band gap of TiO2, resulting in the reduction of the total bandgap and less barrier electron transfer and a redshift in the adsorption edge and enhancement of DSSCs' efficiency.