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Potassium Induced Charge Transfer Effects in OPE-based Molecular Layers



Steven W. Robey, Gregory J. Dutton


The impact of potassium (K) addition on the electronic structure of oligo- (phenylene ethynylene) (OPE) and –NO2 substituted OPE (NO2-OPE) self-assembled monolayers was examined using ultraviolet photoemission. Addition below 0.5 K/molecule produced rigid shifts of molecular levels by about 0.5 eV for both molecular monolayers, with larger shifts at lower K addition for NO2-OPE. Continued addition of K led to increased molecular level shifts for OPE while saturation of the effect was observed for NO2-OPE. For large incorporation of K, modifications of the molecular electronic structure- additional structure and broadening- became evident, again with distinct differences between OPE and NO2-OPE. These results highlight the influence of –NO2 substitution on K induced charge transfer effects. Shifts of the molecular levels are discussed within the context of the electrostatic potential within the monolayer due to K counter ions, coupled with filling of molecular levels, and compared to recent theoretical work.
Journal of Physical Chemistry C


molecular electronics, electronic structure, nanotechnology
Created August 11, 2011, Updated February 19, 2017