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–π-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 Å). The inter-planar DC1 structure exhibited higher aggregation and charge recombination than the trapezoidal DC3 structure, due to strong intermolecular π–π 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 Jsc of 10.8 mA cm−2, a Voc of 0.72 V, and a FF of 0.77, corresponding to an overall conversion efficiency (η) of 6.06%.