Graphene heterostructures with transition metal oxides – investigations of morphology and electronic structure towards applications in organic electronics

Abstract

The unique electrical, optical and mechanical properties of graphene make it attractive as a flexible transparent electrode for applications in organic electronics, e.g. organic light emitting diodes (OLEDs). However, the intrinsic electronic structure of graphene does not match energy levels in organic systems. Such matching can be achieved by depositing a transition metal oxide (TMO) on graphene, creating a heterostructure with new electronic properties. The aim of this work concerns mainly the modification of graphene work function due to interaction with TMO of high work function (WF) with respect to matching the energy levels of the developed heterostructures to the requirements of OLED technology. The core of this thesis addresses synthesis of selected TMOs (molybdenum and rhenium oxides, MoO3 and Re2O7) on graphene and highly oriented pyrolytic graphite (HOPG). The morphology of grown structures was studied in detail, with particular emphasis on molybdenum oxide monolayers. The electronic structure of obtained heterostructures was investigated, in particular, value of work function.