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The study of molecular band offsets at the heteromolecular interface
This thesis covers a research effort to study molecular band offsets and the interplay with interface dipoles. Inorganic electrets and ferroelectrics typically have very poorly characterized surfaces and interfaces. In particular for the perovskites, surface and interface composition is more of a hope than a serial of materials with a good history of reproducible experimental characterization. To address these complexities, I have first focused on molecular systems and molecular heterostructures. Obviously, strong interface dipoles are desirable for such studies. Such systems like polymethylvinylidenecyanide and a variety of ferroelectric polymers are described. All would serve as a suitable substrate. My choice of adsorbate is the planar molecular metal centered macrocyclic semiconductor metal (II) phthalocyanines. The different metal phthalocyanines are compared, particularly with respect to the changes in 3d band filling/depletion, on a conducting substrate Au(111). This provides a benchmark for comparison of metal (II) phthalocyanine adsorption on the molecular ferroelectric polyvinylidene fluoride. There are changes in both of the molecular band offsets and the preferential orientations in the metal (II) phthalocyanines. To add support to the idea that the molecular band offsets can be manipulated by altering the interface dipoles, I fabricated several heterostructure devices. Transport studies show unique hysteresis but support the observed molecular band offsets seen in the combined photoemission and inverse photoemission spectroscopies.
Condensed matter physics
Xiao, Jie, "The study of molecular band offsets at the heteromolecular interface" (2009). ETD collection for University of Nebraska - Lincoln. AAI3360091.