Atomistic computer simulations on point defects and their mobility in metal oxides
Prof. Dr. K. Albe (Div. Material Modelling)
The aim of the project is to obtain a precise understanding of fatigue, which takes place at the interface between transparent conducting oxide (TCO) and organic semiconductor. The work plan can be divided into two parts. Based on Density-functional theory calculations, properties as well as mobilities of vacancies and interstitial atoms will be determined as a function of charge state and chemical potential of the constituents. The future work is based on the results obtained for ZnO. Within this period of funding this knowledge will be extended on indium oxide and the technologically relevant ITO. For the calculation of migration barriers, the “nudged elastic band” and dimer method is applied. The results about defect states within the electrode are then used as input for the second part of the work plan, which aims on the charge transport within the organic semiconducting material, considering the electronic states in the electrode and OLED.
Device properties and fatigue scenarios will be simulated using a lattice gas model, which describes electron transport by a hopping mechanism even in the space charge limited case. The work will be conducted in coordination with subprojects D3 (Klein), D4 (Gassmann / v. Seggern), and C5 (Genenko / v. Seggern).