Observation of two-dimensional weak localization as a sign of coherent carrier transport in the conducting Langmuir–Blodgett films of BEDO-TTF and stearic acid

We report the DC electrical transport properties in the conducting Langmuir–Blodgett (LB) films formed by a molecular association of the electroactive donor molecule bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) and stearic acid CH3(CH2)16COOH. The DC resistivity is 1.25×10−2 Ωcm at 300 K and the temperature variation is metallic. A logarithmic increase of the DC resistivity and the negative magnetoresistance are observed below 120 K. They are interpreted by the weak localization (WL) of a two-dimensional (2D) electronic system confined within the homogeneous conducting layer with molecular size thickness of BEDO-TTF. The existence of the WL indicates that the system is essentially in the coherent regime. A mesoscopic scale of the electronic length with phase memory provides evidence of the 2D coherent charge transport in the conducting LB films.