A remarkable enhancement of efficiency by co-adsorption with CDCA on the bithiazole-based dye-sensitized solar cells

•Three new organic dyes with bithiazole moiety have been synthesized.•The orientation of the bithiazole units plays a key role in dye aggregation.•The best efficiency was 6.31%, which reached 86% of N719-based DSSC.

Three new organic dyes containing a 5,5′-bithiazole or 2,2′-bithiazole entity have been synthesized for dye-sensitized solar cell (DSSC) applications. The conversion efficiencies of DSSCs fabricated are moderate due to serious dye aggregation. Upon addition of CDCA co-adsorbents, the optimized cell efficiencies were improved by 43–86%. The best efficiency was 6.31%, which reached 86% of N719-based DSSC fabricated and measured under similar condition. The efficiency can be further improved to 6.45% by adding a near-IR absorbing dye as the co-sensitizer due to broadened IPCE spectrum.

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