Dye-sensitized solar cells based on square-planar d8 donor complexes without and with organic acceptors

We have recently shown that square-planar Pt(II) complexes with imine and thiolate ligands are good donor complexes that exhibit electronic absorption bands that can be tuned across the UV-vis-NIR region by varying the ligands and/or adding an organic acceptor. However, in order to be useful for dye-sensitized solar cells, these materials need to be anchored to semiconductor surfaces. We achieve this by either the conventional approach in which carboxylated imines are used (e.g., dcbpy = 4,4′-bypyridine(COOH)2 or cttrpy = 4-[2,2′;6′,2″]-terpyridin-4′-yl-C6H4COOH) or by using nitrile organic acceptors such as TCNQ, which can anchor via their cyano groups. We demonstrated that both approaches lead to dyes that can permanently adsorb to semiconductor surfaces and give the same electronic absorption features as those in solution. Details of our spectral, electrochemical, and solar cell results for such dyes using a variety of ligands and d8 metal centers will be presented.