Metallic Conductivity of Langmuir-Blodgett Films Based on Ditetradecyldimethylammonium-Au(dmit)₂, where dmit is 1,3 dithiol-2-thione-4,5-dithiolate

Abstract

Conductive Langmuir-Blodgett films of ditetradecyldimethylammonium-Au(dmit)2 (dmit=1,3 dithiol-2-thione-4,5-dithiolate) have been fabricated without the use of matrix molecules. The in-plane dc conductivity was as high as 40 S/cm after electrochemical oxidation at room temperature. A metallic conductivity with a negative temperature derivative was observed in the temperature range of 250–300 K. At lower temperatures, the temperature dependence of the conductivity was of Arrhenius' type with an activation energy of 2.5 meV.

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

“…770 Some LB films are conductive without the matrix [(2, 10, Pd, 1.0), (4, 10, Pd, 5.1)]. 770,771 Besides the semiconductive LB films, two metallic LB films were prepared after the secondary treatment of electrooxidation [(2, 14, Au, 40), (3, 10, Au, 40)] by Miura et al 772,773 The former and the latter are metallic near RT without and with the matrix, respectively. These LB films after the secondary treatment are rather fragile and the degradation of the LB films soon destroys the conductive behaviors.…”

Development of Highly Conductive Langmuir-Blodgett Films

“…A metallic temperature dependence of resistance is observed from room temperature down to 210-250 K, but the resistance turns to be of an activation type below the temperature showing broad minima of resistance [7,19]. Although for small number of samples, resistance drop on cooling is seen below 4 K, the majority of samples do not exhibit the resistance drop and the macroscopic zero resistance has not been observed for any samples [23].…”

“…A metallic temperature dependence of resistance (a positive temperature derivative) is observed by dc four-probe measurement for the 3C 10 -Au(dmit) 2 LB system [11][12][13][14]. Since then, several LB systems have been reported to have metallic resistance behaviors, i.e., LB systems on BO-C 10 TCNQ [15], BO 2 -(MeO) 2 TCNQ/ CH 3 (CH 2 ) 18 -COOH (matrix) [16], BO-BA(behenic acid) [17], and ditetradecyldimethylammonium-Au(dmit) 2 [2C 14 -Au(dmit) 2 ] salt [18,19]. The widest temperature range of metallic resistance, 14 K-300 K, is observed for the BO-BA LB system [17].…”

“…We have already pointed out that the LB system based on ditetradecyldimethylammonium-Au(dmit) 2 (2C 14 -Au(dmit) 2 , Fig.1) salt shows a room temperature conductivity of 40 S/cm with a metallic behavior of conductivity after electro-oxidation [7]. Furthermore, the ac magnetic susceptibility measurement suggests that the 2C 14 -Au(dmit) 2 LB system has a superconducting phase below 4 K [8].…”

Epitaxial Growth of Conductive Charge-transfer Complex in the Organized Molecular Film on Fluorinated Copolymer as Template

“…7 The LB films of dialkylammonium-Au(dmit) 2 salts exhibited a high lateral conductivity of 40 -100 S/cm at room temperature after electrochemical oxidation or I 2 doping, and had metallic temperature dependence of the conductivity. 8,9 Furthermore, the ac magnetic susceptibility and resistance suggested the existence of a super conducting phase below 4 K. 10 Bryce and Petty reported electrical conductivity of LB films for charge-transfer complexes containing metal(dmit) 2 .…”