Effect of Thermal Annealing on the Charge Carrier Mobility in a Polymer Electroluminescent Device

Effect of thermal annealing on the time-of-flight charge carrier mobility of a polymer electroluminescent device was investigated. The average hole mobility of the device before annealing was ∼1×10−6 cm2/V/s, while the thermally annealed device demonstrated both dispersive carrier transport characteristics and enhanced carrier mobility (∼3×10−6 cm2/V/s). This is attributed to the increased interchain interactions achieved by thermal annealing. It was clarified that with the higher degree of interchain interactions the faster becomes the charge carrier mobility. We propose the thermal annealing method as a convenient and effective mean to improve the carrier mobility of the devices based on organic/polymeric semiconducting materials.