EXPLORING THE ROLE OF DEFECTS ON CHARGE TRANSPORT IN ORGANIC SEMICONDUCTORS

摘要

Organic semiconducting materials such as conjugated polymers and fullerenes are the foundation of various next-generation solar energy technologies. Unlike their often highly crystalline inorganic counterparts, these materials are inherently riddled with a variety of defects. Understanding how various defects, whether they be conformational disorder or trapped charges, influence electronic structure and charge transport is a crucial step toward improving device performance. Increased charge density has been reported to increase charge mobility in organic semiconductors in a variety of studies, with this effect usually explained by trap filling permitting trap-free transport for the remaining charges. Here, we use first- principles density functional theory (DFT) calculations with point charges proximal to C70 fullerene molecules to investigate whether, irrespective of trap effects, charge density may affect electronic structure in ways that promote transport.