Band dispersion and electronic lifetimes in crystalline organic semiconductors

The consequences of several microscopic interactions on the photoemission spectra of crystalline organic semiconductors (OSC) are studied theoretically. It is argued that their relative roles can be disentangled by analyzing both their temperature and their momentum/energy dependence. Our analysis shows that the polaronic thermal band narrowing, that is the foundation of most theories of electrical transport in OSC, is inconsistent in the range of microscopic parameters appropriate for these materials. An alternative scenario is proposed to explain the experimental trends.