Influence of different anchor-bridge groups on electron transfer from the molecular chromophore perylene to the wide gap semiconductor TiO2

Abstract

This chapter presents a report on transient absorption experiments in ultrahigh vacuum that probe heterogeneous electron transfer from the molecular chromophore perylene via different molecular anchor-bridge groups into nm-structured anatase TiO2 layers. Transport of electrons through molecular units is an important topic in the field of molecular electronics and future device modeling. The strength of electronic coupling between a molecular chromophore and a semiconductor can be varied with different molecular bridge units inserted between the chromophore and anchor group. The measured electron transfer times show conducting or insulating behavior of the respective bridge unit, -C=C- and -C-C-. Heterogeneous electron transfer times were measured with different bridge-anchor groups in ultrahigh vacuum where the wide band limit is realized for the perylene/TiO2 system. The experimental data should allow for a more direct comparison with theoretical calculations because they are neither complicated by the presence of a solvent environment nor by specific Franck–Condon factors.