Model of vinylstilbenedecaphenylsilsesquioxane showing 3D-structure

Richard Laine

Most common organic solar cells use materials, which are composed mainly of expensive organic polymeric compounds such as P3HT and PCBM. Our goal is to synthesize silsesquioxane (SQ) nanostructures that contain functionality similar to those organic compounds, while increasing the lifetime and stability of the cells, while also lowering the cost of production. One of the main challenges to this process is tuning the band gap of the SQ cage. Research has shown that SQs show conjugation in the excited state as exhibited by absorption, fluorescence and two-photon spectroscopy. These compounds show the ability to tune the band gap by changing the organic functionality around the cage, either by enacting polymerization techniques known as BOC (beads on a chain), in which organic linkers are placed between the cages, or by changing the electron withdrawing or donating ability of the organic substituents. Other work is also being performed in order to synthesize broad spectrum absorbing compounds, which would allow for efficient energy transfer. Multiple techniques are being employed, from adding small monomer units one step at a time to attaching full conjugated dye molecules to the core. The ability to attach so much functionality in a nanometer-sized area is of great interest not only for solar cells, but also for the possibilities to form stable laser dyes and standards.