A Bis(tridentate)cobalt Polypyridine Complex as Mediator in Dye‐Sensitized Solar Cells

摘要: Dye-sensitized solar cells equipped with cationic and neutral RuII-based sensitizers [Ru(ddpd){tpy(COOH)3}]2+ [12+; ddpd = N,N′-dimethyl-N,N′-di(pyridin-2-yl)pyridin-2,6-diamine, tpy(COOH)3 2,2″6′,2″-terpyridine-4,4′,4″-tricarboxylic acid] [Ru(ddpd){tpy(COOH)(COO)2}] (2) without the coadsorbent chenodeoxycholic acid were constructed I3–/I– or CoIII/II-based redox mediators [Co(bpy)3]3+/2+ (33+/2+; bpy 2,2′-bipyridine) [Co(ddpd)2]3+/2+ (43+/2+) in presence of LiClO4 4-tert-butylpyridine. The best photovoltaic performance was achieved by using 43+/2+ shuttle sensitizer 2 coadsorbent. higher short-circuit photocurrent density electron recombination lifetimes obtained this combination suggest slow kinetics at TiO2 surface CoIII complex 43+. transfer to 43+ is tentatively ascribed high-lying π* orbitals electron-rich ligands, which result a weak electronic coupling. This contrasts faster 33+, features low-energy ligands.