Infrared and Electro-Optic Properties of TIPS-Pentacene*

We will discuss new measurements of the infrared and electro-optic properties of thin crystals of triisopropylsilylethynyl (TIPS) pentacene. As with THz studies of this class of materials, crystalline films were grown from saturated tetrahydrofuran solutions on a gold electrode mask. Square wave voltages were applied to the electrical contacts on the sample as well as a gate electrode below the sample, through an oxide dielectric. Changes in phonon frequencies were studied as functions of voltage, position between contacts, and frequency of applied voltage.~ The results are interpreted in terms of charge diffusion through the TIPS-pentacene crystals.