STM Study of Donor-Bridge-Acceptor Molecules Having Different Bridge Structure

Composite molecular solar cells form an interesting alternative to traditional silicon or gallium arsenide solar cells. In order to increase the efficiency these molecular systems, a deeper understanding of the microscopic mechanisms at work in organic solar cells is needed. Using scanning tunneling microscopy and spectroscopy we have investigated donor-bridge-acceptor molecules having different bridge structures covalently bonding similar donor and acceptor elements. Structural and electronic properties of individual molecules and self-assembled molecular chains will be presented. This study is aimed toward controlling energy conversion pathways within molecular solar cells and for developing higher efficiency solar cell materials.