Supramolecular electrolytes with multiple hydrogen bonds for solid state dye-sensitized solar cells

Abstract

Oligomeric supramolecules with double- (2H-P), triple- (3H-P) and quadruple H-bonding sites (4H-P) at their both chain ends of PEG (Mw = 2000) are successfully utilized to increase energy conversion efficiency for solid state dye-sensitized solar cells. The improved energy conversion efficiency is due mostly to the deeper penetration of the liquid oligomeric supramolecular electrolytes into the nanopores of the TiO2 layer, followed by in situ self-polymerization via multiple H-bonds and the improved ionic conductivity. Among the three solid state dye-sensitized solar cells, the 2H-P and 3H-P electrolytes shows better photovoltaic performances than the 4H-P electrolyte. The difference in the performance is mostly attributable to the fact that the 2H-P and 3H-P electrolytes have a slower electron recombination rate and a faster ionic diffusion coefficient, compared to the 4H-P electrolyte. Therefore, the characters of the liquid and the solid states of the supramolecules may have been able to be successfully utilized to increase the energy conversion efficiency over 4% for solid state dye-sensitized solar cells.