Charge Transport in Organic Semiconductors: Mechanisms and Interfaces

This lecture discusses the charge transport mechanisms in organic semiconductors, focusing on the active regions in p-type and n-type materials. It begins with an overview of the Fermi distribution and Fermi level, explaining how these concepts relate to charge carriers in different materials. The instructor elaborates on the significance of charges at interfaces, particularly in organic semiconductor devices that are sandwiched between electrodes. The lecture covers the density of occupied states in metals, semiconductors, and insulators, emphasizing the temperature dependence of charge transport. Various transport regimes are introduced, including coherent transport, polaronic transport, and disorder-controlled transport, highlighting the differences in charge mobility and conductivity between inorganic and organic materials. The discussion also includes the role of dynamic and static disorder in charge transport, as well as the influence of electrode materials on charge injection processes. The lecture concludes with a summary of the challenges and considerations in designing efficient organic electronic devices.