Assembling quinolinium-based chromophores on silicon surfaces provides a new route to electronic control over such semiconducting surfaces. The two-step process by which the molecules are grafted on to the surface involves first coupling the organic functionality to silicon, followed by chromophore anchoring. These synthetic steps are monitored by XPS, UV - Vis and FTIR spectroscopies. Using contact potential difference measurements we found that the electron affinity of the modified silicon is a function of the molecule's dipole moment. The same technique shows a pronounced effect of the sub-nanometer siloxane-based, coupling-agent, layer by itself on the band bending and band-bending modification as function of chromophore adsorption.
Bibliographical noteFunding Information:
SY acknowledges support for this research by the Israel Science Foundation. DC thanks the US-Israel Binational Science Foundation, and the Minerva Foundation, Munich, for partial support. We thank Dr. Hagai Cohen for his help in the XPS measurements.