A new terpyridine cobalt complex redox shuttle for dye-sensitized solar cells

A new cobalt-terpyridine redox shuttle ([Co(Cl-phenyl-terpyridine)2]2+/3+) has been synthesized, characterized, computationally investigated and then tested in photovoltaic devices, in conjunction with the prototypical N719 and Z907 ruthenium dyes. Lower efficiencies compared to the reference [Co(bpy)3]2+/3+ redox couple were obtained, probably due to increased recombination processes. Improvements in the devices performances were obtained by using chenodeoxycholic acid as surface co-adsorbent and as an electrolyte additive. Moreover, to better rationalize the photovoltaic results, the effect of two different counterions (TFSI and PF6) has been investigated for the reference [Co(bpy)3]2+/3+ electrolyte, finding a reduced efficiency for the TFSI-based electrolyte.