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)