Sensitization of Nanocrystalline TiO₂ with Black Absorbers Based on Os and Ru Polypyridine Complexes

Abstract

New metal complexes of the type [M(H3tcterpy)LY]+ (where M = Os(II) or Ru(II), L = substituted or unsubstituted bipyridine or pyridylquinoline, and Y = Cl-, I-, or SCN-) have been designed, synthesized, and characterized in view of their application for dye-sensitized solar cells (DSSCs). The Os dyes show a very broad absorption, and correspondingly, the DSSCs show an unprecedented spectral response in the NIR, with an onset at 1100 nm, reaching values of about 50% at 900 nm. The integrated photocurrent of some of such Os dyes is similar to that of the well-known [Ru(Htcterpy)(NCS)3](TBA) and superior to that of the [Ru(Hdcbpy)2(NCS)2](TBA)2 sensitizer. The Ru dyes show absorption and DSSC spectral response between those of the red and black dyes. Their advantage is their potential superior stability due to the reversible oxidative electrochemistry.

Characterizing the Solvated Structure of Photoexcited [Os(terpy)2]2+ with X-ray Transient Absorption Spectroscopy and DFT Calculations

“…Unlike for most of the ruthenium-based analogues, the absorbance now covers the full visible range~400 nm to 800 nm, thereby matching a larger fraction of the solar spectrum. DSSCs incorporating various Os molecular complexes have indeed achieved high incident photon-to-electron conversion efficiency deep into the near infrared region [5][6][7][8][9][10][11]. Concurrently, the strong spin-orbit coupling (SOC) increases the d-d splitting, moving the positions of the metal-centered states higher up in energy when compared to their Ru analogues, thereby improving the thermal stability of the photoexcited complexes.…”

Synthesis, Photo-, and Electrochemistry of Ruthenium Bis(bipyridine) Complexes Comprising a N-heterocyclic Carbene Ligand

“…Complexes of iridium, 3 copper, 4 platinum, 5 iron, 6 rhenium, 7 and osmium 8 have been used as sensitizers, though the most abundant systems are undoubtedely those derived from [Ru(bpy) 3 ] 2+ . 9 In particular, these photoactive complexes have been used extensively and successfully in dye-sensitized solar cells (DSSCs).…”

Dye-Sensitized Solar Cells Using Fresh and Dried Natural Dyes

“…Due to the dye significant role, considerable interest has been directed towards the development and improvement of new families of organic dyes and of metal complexes. So far, the most efficient dye is found to be Ru(II) [13,14] and Os(II) [15]. These complexes have a number of interesting features such as good absorption, long excited lifetime, and highly efficient metal-to-ligand charge transfer.…”