Enhance the performance of co-sensitized solar cell by a series efficient pyridine-anchor co-adsorbents of N,N′-bis((pyridin-2-yl)methylene)-p-phenylenediimine and a ruthenium dye of N719

Abstract A pyridine-anchor co-adsorbent N,N′-bis((pyridin-2-yl)methylene)-p-phenyl- lenediimine (named L1) and its derivatives N,N′-bis((6-methoxylpyridin-2-yl)methylene)- p-phenylenediimine (named L2) and N,N′-bis((pyridin-2-yl) (methyl)methylene)-p-phenyl- enediimine (named L3) are synthesized and employed in combination with a ruthenium complex N719 in dye sensitized solar cells (DSSCs). The prepared co-adsorbent can overcome the deficiency of N719 absorption in the low wavelength region of visible spectrum, offset competitive visible light absorption of I₃^-, suppress the charge recombination and prolong the electron lifetime. The introduction of methyl or methoxyl substituent also has some effect on the performance of DSSCs. A short circuit current density of 14.60 mA cm^-2, an open circuit voltage of 0.75 V and a fill factor of 0.63 corresponding to an overall conversion efficiency of 6.92% under AM 1.5G solar irradiation are achieved when L2 is used as co-adsorbent, which is 30% higher than that for DSSCs only sensitized by N719 (5.31%) under the same condition. Mechanistic investigations are carried out by various spectral and electrochemical characterizations.