  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.
