Transition Metal Complexes as Sensitizers for Efficient Mesoscopic Solar Cells

In this review, I will describe our research in the field of molecular engineering of transition metal complexes for use as sensitizers in dye sensitized solar cells (DSC), light emitting agents in organic light-emitting diodides (OLEDs) and self assembled molecular charge transport layers in electronic devices. Thanks to the development of ruthenium complexes acting as very efficient sensitizers the DSC reaches currently conversion efficiencies over 11 percent and excellent stability rendering it a credible alternative to silicon devices. The industrial development is advancing rapidly, commercial manufacturing of the DSC having recently been announced. The cell is a viable contender for large-scale future solar energy conversion systems on the bases of cost, efficiency, stability, availability and environmental compatibility. Heteroleptic ruthenium complexes endowed with ion coordinating ligands have shown unprecedented performance in solid state dye sensitized photovoltaic devices. Electron transfer from the excited ruthenium sensitizer into the conduction band of the nanocrystalline titanium dioxide film occurs within femtoseconds. Rapid cross surface hole transfer within self-assembled monolayer of transition metal complexes [complexes have also been witnessed. The saline kinetic features of these interfacial and cross-surface charge transfer reactions will be discussed. Apart from dye-sensitized solar cells these transition metal complexes offer also great promise for a new generation of electroluminescent systems. Examples of these devices will be presented and their mode of operation will be discussed.