Recent advances in phenothiazine-based dyes for dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have attracted significant attention as alternatives to conventional silicon-based solar cells owing to their low-cost production, facile fabrication, excellent stability and high power conversion efficiency (PCE). The dye molecule is one of the key components in DSSCs since it significant influence on the PCE, charge separation, light-harvesting, as well as the device stability. Among various dyes, easily tunable phenothiazine-based dyes hold a large proportion and achieve impressive photovoltaic performances. This class of dyes not only has superiorly non-planar butterfly structure but also possesses excellent electron donating ability and large π conjugated system. This review summarized recent developments in the phenothiazine dyes, including small molecule phenothiazine dyes, polymer phenothiazine dyes and phenothiazine dyes for co-sensitization, especially focused on the developments and design concepts of small molecule phenothiazine dyes, as well as the correlation between molecular structures and the photovoltaic performances.