Dual-channel anchorable organic dyes with well-defined structures for highly efficient dye-sensitized solar cells

Abstract

Dual-channel (DC) anchorable organic dyes with well-defined structures, based on an acceptor-pi-donor-core bridge-donor-acceptor structural motif, were synthesized and used as sensitizers for dye sensitized solar cells (DSSCs). The new synthetic approach implies the use of two donors, two acceptors and a core bridge as a spacer. DC dyes linked the two donors using a core bridge such as m-phenylene and fluorene units, which makes two channels maintaining a particular distance (> 4 angstrom). The inter-planar DC1 structure exhibited higher aggregation and charge recombination than the trapezoidal DC3 structure, due to strong intermolecular pi-pi stacking between the channels of DC dyes adsorbed on the TiO2 surface. The DC3 dye had a broader light-harvesting range than DC1, while the DC3 dye with HC-A1 was less efficient than the DC1 dye with HC-A1. Thus, the effect of the chemical structure of a DC sensitizer on DSSC performance was studied. As a result, a solar cell based on DC1 with HC-A1 showed better photovoltaic performance with a J(sc) of 10.8 mA cm(-2), a V-oc of 0.72 V, and a FF of 0.77, corresponding to an overall conversion efficiency (eta) of 6.06%.