High-Performance Dye-Sensitized Solar Cells Based on Phenothiazine Dyes Containing Double Anchors and Thiophene Spacers

A series of new push-pull phenothiazine-based dyes (HL1-HL4) featuring various spacers (thiophene, 3-hexylthiophene, 4-hexyl-2,2-bithiophene) and double acceptors/anchors have been synthesized, characterized, and used as sensitizers for dye-sensitized solar cells (DSSCs). Among them, the best conversion efficiency (7.31%) reaches approximately 99% of the N719-based (7.38%) DSSCs fabricated and measured under similar conditions. The dyes with two anchors have more efficient interfacial charge generation and transport compared with their congeners with only single anchor. Incorporation of hexyl chains into the -conjugated spacer of these double-anchoring dyes can efficiently suppress dye aggregation and reduce charge recombination.