Rigorous Characterization and Predictive Modeling of Hole Transport in Amorphous Organic Semiconductors

Amorphous small-molecule hole-transporting materials are commonly used in organic light-emitting diodes and perovskite solar cells. Characterization of their main functionality, hole transport, has been complicated by the presence of large contact barriers. Using a recently developed technique to establish Ohmic hole contacts, the bulk hole transport in a series of molecules with a broad range of ionization energies is investigated. The measured charge-carrier mobility dependence on charge concentration, electric field, and temperature is used to extract the energetic disorder and molecular site spacing. Excellent agreement of these parameters as well as ionization energies with multiscale simulations paves the way to predictive charge-transport simulations from the molecular level.