Synthesis and evaluation of simple molecule as a co-adsorbent dye for highly efficient co-sensitized solar cells

•One simple-structure dye and two bulky dyes have been designed for co-sensitized solar cells.•Exploring a new co-sensitization system utilizing synergy between simple-structure and bulky organic dyes.•Simple molecule as a co-adsorbent dye to fill up the space defects between bulky dyes by molecular size matching.•Increase of light-harvesting ability by complementary absorption.

One simple-structure dye and two bulky dyes have been designed for exploring a new co-sensitization system utilizing synergy between simple-structure and bulky organic dyes. This small-sized dye molecule can fill up the space defects between bulky dyes, and its strong absorption band from 350 to 500 nm can complement the absorption valleys of the bulky dyes. Additionally, the dye loading of titanium dioxide surface was investigated by Thermogravimetric analysis, which confirms that the molar loading of co-sensitized device has significantly increased. These results exhibit that the simple molecule can be used not only as a co-adsorbent to inhibit charge recombination and π-π aggregation between the bulky dyes but also as a co-sensitizer to improve light-harvesting ability.

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