Infrared probe of charge dynamics in single crystal rubrene organic field-effect transistors

We report on infrared (IR) spectroscopy of charge dynamics in organic field-effect transistors based on single crystal rubrene. IR microscopy measurements show uniform charge injection over macroscopic length scales of several millimeters in these devices. IR measurements uncover anisotropic optical conductivities of these transistors in agreement with earlier transport studies. The field-induced electronic excitations in rubrene reveal optical constants with the Drude-like form and low effective masses. I will discuss several new aspects of the charge dynamics in organic molecular crystals uncovered by this work.