Comparison of hole mobility in thick and thin films of a conjugated polymer

The problem that conventional time of flight (TOF) mobility measurements are made on much thicker films than typically used in organic optoelectronic devices is investigated by comparing the mobility of thick and thin films of the poly(phenylenevinylene) based copolymer “SuperYellow”. We report for the first time mobility values perpendicular to the substrate for this widely used material and find them to be of the order of 10−6–10−7 cm2/V s for both spin-coated and drop-cast films. A high photoluminescence quantum yield (PLQY) of 60 ± 5% is measured for both types of films. The results indicate a trade-off between PLQY and charge transport in poly(arylenevinylene)s. The insensitivity of the charge transporting and photophysical properties to the film preparation procedure and thickness is a desirable characteristic that may result from the bulky side groups of “SuperYellow”.