Interaction between Charge-transfer States Studied by Magnetic Field Effects

Organic semiconducting materials, consisting mostly of carbon and hydrogen atoms, provide remarkable promise for electronic applications due to their easy processing, chemical tenability, low costs and environmental-friendly characteristics. For realizing electronic applications such as light emitting diodes and photovoltaic cells, charge-transfer states act as an important intermediate state for recombination and dissociation. Interestingly, magnetic field effects on semiconducting materials have been realized based on the suppression of spin mixing in the charge-transfer states. Although lots of studies have been carried out on investigating the properties of charge-transfer states, little has been done to consider the interaction between them. This thesis aims to reveal the interaction between different kinds of charge-transfer states by using the magnetic field effects. Chapter 1 presents a basic introduction to the organic semiconducting materials and magnetic field effects. Chapter 2 gives a simple description of the experiment procedure, such as device fabrication, magnetic field effects measurement and data analysis. Chapter 3 studies the interaction between intermolecular charge-transfer states. Chapter 4 indicates the interaction between intramolecular charge-transfer states and d electrons. Chapter 5 illustrates the interaction between photo-generated and magnetized charge-transfer states. Chapter 6 introduces the interaction between excitons and free charge carriers in organo-metal halide perovskite materials. Chapter 7 performs the study of magneto-electronic interaction at the interface between Rashba perovskite and ferromagnetic metal. Finally, Chapter 8 gives a short conclusion for the entire study in this dissertation.