CHARGE-CARRIERS MOBILITY ENHANCEMENT BY ELECTROCHEMICAL INCLUSION OF METALLIC-IONS IN SEXITHIOPHENE THIN-FILMS

The free-carrier mobility of semiconducting sexithiophene alpha-6T in thin film can be enhanced by two or three orders of magnitude by electrochemical inclusion of Ag and Cu ions. Mobilities up to 0.7 cm2 V-1 s-1 are obtained with Au/alpha-6T/Au symmetrical structures. The analysis of current-voltage curves shows the existence of a purely ohmic behavior at low potentials (V < 0.1V) followed by a space charge limited current regime (SCLC) at potentials higher than 0.5V. This result can be explained by (1) a decrease of the front contact resistance and (2) the creation of metallic bridges improving the inter-chain charge transfer rate. This technique can be used towards molecular electronic devices such as field-effect transistors.