EES Blog

Researchers led by Professor Christoph Langhammer have developed a novel tool based on indirect nanoplasmonic sensing for in situ studies of dye-sensitized solar cells (DSSCs). Their work elucidates the kinetics of dye impregnation into mesoporous TiO₂, known to be a critical step in fabrication of DSSCs and therefore important for scale-up of DSSCs.

DSSCs offer a potentially low-cost, aesthetically appealing alternative to conventional silicon based technologies. The key components of a cell are a TiO₂ film filled with a densely packed monolayer of photon absorbing dye molecules and an electrolyte. Mechanism-oriented tools and studies are needed to understand how to reproducibly form an optimal dye monolayer on the TiO₂ and how to make the DSSC fabrication process compatible with industrial demands. Langhammer’s group has done exactly that by using a new method to follow the dye impregnation process in detail.

The researchers use Hidden Interface-Indirect Nanoplasmonic Sensing (HI-INPS), a technique that uses the localized surface plasmon resonance of Au nanoparticles (coated with a thin dielectric layer). When illuminated with near-visible light, their sensitivity to dielectric changes. This sensitivity is short- ranged, typically within 50–100 nm from the sensor particle surface. Therefore if a thick layer of material, like mesoporous TiO₂, is deposited onto such a sensor chip, the plasmonic Au sensor particles probe the hidden interface region between the sensor chip surface and the sample material. HI-INPS is a neat way to monitor the dye molecule adsorption without disturbing the DSSC.