Fifth Generation Polyurethane Dendrimers Decorated with Protected Amine, Free Amine and Blocked Isocyanate End Groups: Synthesis and Electrolytic Performance to Increase the Efficiency of Dye‐Sensitized Solar Cell

Abstract

AbstractFifth generation polyurethane dendrimers decorated with trifluoroacetamide, free amine and blocked isocyanate end‐groups were prepared and their structures were confirmed using FT‐IR, 1H and 19F‐NMR, MALDI‐TOF MS and size exclusion chromatography (SEC‐MALS) techniques. The hydrodynamic diameter and zeta potential of dendrimers were measured using dynamic light scattering (DLS) technique; the later parameter indicated that the dendrimer containing trifluoroacetamide end‐group (1) stabilized more in the medium. The effect of different end‐groups on photophysical, electrochemical and thermal properties of dendrimers were also evaluated; dendrimer with blocked isocyanate end‐groups (3) absorbed low light, showed two redox potential and exhibited glass transition temperature (Tg). All the dendrimers were used as electrolytes in combination with LiI for N719 dye‐sensitized solar cells (DSSCs) and found that the DSSC fabricated with blocked isocyanate‐terminated dendrimer (3) yielded nearly 2.5 times high power conversion efficiency (ɳ=8.04% upon illumination with 0.5 sun intensity) compared to the cell fabricated with only LiI electrolyte.