Carrier-density dependence of the hole mobility in doped and undoped regioregular poly(3-hexylthiophene) - Brondijk, JJ; Maddalena, F; Asadi, K; van, Leijen HJ; Heeney, M; Blom, PWM; de, Leeuw DM (PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 2012)