Co(III) Complexes as p-Dopants in Solid-State Dye-Sensitized Solar Cells

Following our recent work on the use of Co(III) complexes as p-type dopants for triarylamine-based organic hole-conductors, we herein report on two new Co(III) complexes for doping applications. With the aim of ameliorating the dopant's suitability for its use in solid-state dye-sensitized solar cells, we show how the properties of the dopant can be easily adjusted by a slight modification of the molecular structure. We prove the eligibility of the two new dopants by characterizing their optical and electrochemical properties and give evidence that both of them can be used to oxidize the molecular hole-transporter spiro-MeOTAD. Finally, we fabricate high-performance solid-state dye-sensitized solar cells using a state-of-the-art metal-free organic sensitizer in order to elucidate the influence of the type of dopant on device performance.