Evaluating intrinsic mobility from transient terahertz conductivity spectra of microcrystal samples of organic molecular semiconductors

In microcrystal samples of the prototypical organic molecular semiconductors rubrene and C-10-DNTT (2,9-didecyl-dinaphtho[2,3-b:2 ',3 '-f]thieno[3,2-b]thiophene), we measured spectra of complex optical conductivity caused by photocarriers with optical-pump terahertz-probe spectroscopy. We analyzed the (sigma) over tilde(omega) spectra using the Drude-Smith model and evaluated the DC mobility mu(DC), which includes extrinsic effects, and the intrinsic mobility mu(int). The resulting mu(DC) and mu(int) values are comparable to the mobility values obtained using transport measurements of polycrystalline and single-crystalline field-effect transistors, respectively. This correspondence demonstrates that the intrinsic mobility values of organic molecular semiconductors can be evaluated from the measurements of microcrystal samples using transient terahertz spectroscopy. Published under license by AIP Publishing.