A simple triaryl amine-based dual functioned co-adsorbent for highly efficient dye-sensitized solar cells

We have developed 4-(bis(9,9-dimethyl-9H-flouren-2-yl)amino)benzoic acid (HC-Acid) to use as an alternative co-adsorbent to deoxycholic acid (DCA) in organic dye-sensitized solar cells (DSSCs). It has dual functioned effects, that is, the prevention effect of the pi-pi stacking of organic dye molecules like DCA and the light harvesting effect at shorter-wavelength regions. When the HC-Acid was used as the co-adsorbent onto the TiO2 surface with the organic dye NKX2677 sensitized solar cell, an extremely high conversion efficiency of 9.09% was achieved under 100 mW cm(-2) AM 1.5G simulated light (J(sc) = 18.01 mA cm(-2), V-oc = 0.663 V, and FF = 76.16). As we herein demonstrate, an increase in short-circuit photocurrent density (J(sc)) of 20%, open-circuit photovoltage (V-oc) of 11% and overall conversion efficiency (eta) of 38% occurred in comparison to the NKX2677 based solar cell. As a consequence, this new class of a low molecular weight organic co-adsorbent (HC-Acid) is a promising candidate as an alternative co-adsorbent with a new function not seen in DCA or CA derivatives for highly efficient dye-sensitized solar cells.