Synthesis of a Squaraine-Based Dye for Dye-Sensitized Solar Cells

With the prediction of fossil fuel depletion in the near future, solar energy alternatives have taken rise.  To make a solar cell from unlimited resources, organic dyes should be utilized as sensitizers in solar cells. However, these cells efficiencies are not up to par with metal alternatives. Higher efficiencies in dye-sensitized solar cells are attributed to wider spectral distributions. Therefore, it is hypothesized that if the x-bridge (linkage between a dye and anchor) of a squaraine-based dye is changed to one that is more conjugated, there will be a bathochromic shift as well as more absorption coverage in the higher energy region of the molecules absorption spectra. Extended conjugation can also result in overall wider spectral distributions. The dye was synthesized in a two part seven step process based on previous research. After conducting the experiment, the x-bridge in the dye molecule was shown to shift the dye absorption about 25 nm toward the red–near-infrared region confirming that extending the conjugation of this particular dye would cause a bathochromic shift in the absorption.