First Report of Chenodeoxycholic Acid–Substituted Dyes Improving the Dye Monolayer Quality in Dye-Sensitized Solar Cells

摘要

Chenodeoxycholic acid (CDCA) is the most used antiaggregation additive in dyesensitized solar cells since its introduction to the field in 1993. However, effective suppression of dye aggregation comes at the cost of reduced dye loading, a lower open-circuit voltage, and limited control of dye/additive distribution when cosensitizing with free CDCA. To combat this, herein, a novel dye design concept that uses the covalent attachment of a CDCA moiety to triarylamine sensitizers is reported. The CDCA substituents do not affect the photophysical or electrochemical properties of the sensitizers but have a positive effect on the photovoltaic performance with [Cu~(+/2+)(tmby)_2](TFSI)_(1/2) electrolyte (tmby = 4,4 0,6,6 0- tetramethyl-2,2 0-bipyridine, TFSI = bis(trifluoromethanesulfonyl)imide). By ensuring a one-to-one ratio of dye and CDCA, paired with isotropic distributions of each component, this approach results in a higher-quality dye monolayer. Compared with the reference system, the novel approach reported herein gives a higher open-circuit voltage and power conversion efficiency (PCE). The best device is fabricated with the dye C_6–CDCA, delivering a PCE of 6.84% (8 μm TiO_2, 1mM CDCA, J_(SC) = 8.64 mA cm~(-2), V_(OC) = 1007 mV, and FF = 0.77).