Fundamental Studies of Disorder\n

Fundamental Studies of Disorder
Soft semiconductors are materials that are held together by van der Waals forces rather than the stronger covalent bonds that are more typical of conventional semiconductors such as Si. Examples of soft semiconductors are molecular crystals and thin films of molecules and polymers. Due to weak intermolecular interactions, disorder is found in all soft semiconductors. Even molecular crystals possess thermodynamically-stable molecular vacancies that cannot be removed by annealing.

We examine the influence of disorder on charge injection from metal contacts into thin, disordered semiconductors. Charge injection dominates the performance of many organic devices. For example, the operating voltage of OLEDs based on small-molecular weight materials is typically determined by charge injection. We have proposed that interfacial disorder is a critical determinant of charge injection into soft semiconductors.