Organic dyes with a fused segment comprising benzotriazole and thieno[3,2-b]pyrrole entities as the conjugated spacer for high performance dye-sensitized solar cells

Abstract

Sensitizers with a fused segment comprising electron deficient benzotriazole (BZ) and electron rich thiophene or thieno[3,2-b]pyrrole entities as the conjugated spacer have been synthesized for dye-sensitized solar cells (DSSCs). The power conversion efficiency (PCE) increases with elongation of the conjugated spacer, and the dye with the dithieno[3,2-b]pyrrolobenzotriazole spacer has the best efficiency of 8.14%, which is comparable with that of an N719-based DSSC (8.03%). After coadsorbed with 1 mM CDCA, the efficiency was improved to 8.4%. The J-aggregation of the dye results in light harvesting at a longer wavelength spectral region and increasing the photocurrent of the cell.