Two novel mono-hydroxyl pyranoanthocyanidins bearing dimethylamino substituent(s) for dye-sensitized solar cell

Two novel analogues (AF3-1 and AF3-2) of natural pigments that were originally found in wine product, pyranoanthocyanidins, were designed based on pyrano-4′-dimethylamino-10-phenyl-flavylium (AF3) by respectively introducing another electron donor(s), dimethylamino and two methoxyl groups, to the phenyl moiety. They were synthesized and then successfully applied as sensitizers in DSSC to study effect of the additional donor(s) on the DSSC performance for such pyranoanthocyanidin. The introduced second dimethylamino substituent of AF3-1 slightly red shifts the absorption spectrum. Both title dyes show relatively strong ability to shield the photoanode surface from electrolyte and to restrain the electron recapture process. Yet it is difficulty for them to adsorb on the semiconductor surface effectively and to avoid undesirable dye aggregation. DSSCs based on the designed pyranoanthocyanidin turn out to have much higher V oc but decreased J sc compared to AF3. PCE of DSSC assembled with the better of the two pyranoanthocyanidins, AF3-1, is 1.79%, on the same level as that of the reference sensitizer.