Energy levels and charge transport in host-dopant organic semiconductors
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Organic light-emitting diodes (OLEDs) have become one of the mainstream display technologies due to their excellent image quality and flexible form factor. A current challenge in the OLED industry is to achieve highly efficient and stable blue devices. The efficiency and lifetime of OLEDs can be boosted through having a balanced electron and hole transport in the emissive layer of the OLEDs. The emissive layer consists of an organic host doped with an emissive dopant molecule. The charge transport process in this material system is dependent on the energy level alignment at the host-dopant interface. However, both the energy level alignment and charge transport processes are not fully understood in the community. In this presentation, I will first show a universal rule to predict energy level alignment at host-dopant interfaces. After that, I will talk about the impact of interface energy disorder in amorphous organic semiconductors on the host-dopant energy level alignment. Next, I will present charge transport mechanisms, i.e., charge detrapping and percolation, in host-dopant organic semiconductors. Lastly, I will discuss charge injection into host-dopant organic semiconductors.
Peicheng Li is a PhD candidate in the Department of Materials Science and Engineering at the University of Toronto. His research focuses on materials and device physics of organic optoelectronics. He has won a few awards including the Alexander Graham Bell Canada Graduate Scholarship.