Polarization of charge-transfer bands and rectification in hexadecylquinolinium 7,7,8-tricyanoquinodimethanide and its tetrafluoro analog

A Langmuir-Blodgett (LB) multilayer film of the unimolecular rectifier hexadecyl-gamma-quinolinium-7,7,8-tricyanoquinodimethanide (C(16)H(33)gammaQ-3CNQ) has two distinct polarized charge-transfer bands, one at lower film pressures (28 mN m(-1)) with a peak at 530 nm, due to an intramolecular charge transfer or intervalence transfer (IVT); past the collapse point (32 to 35 mN m(-1)), this band disappears, and a new intermolecular charge-transfer band appears with peak at 570 nm. An LB multilayer film of the tetrafluoro analogue, hexadecyl-gamma-quinolinium-2,3,5,6-tetrafluoro-7,7,8-tricyanoquinodimethanide (C(16)H(33)gammaQ-3CNQF(4)) shows, for all film pressures, only one IVT band with a peak at 504 nm; when sandwiched between gold electrodes, (C(16)H(33)gammaQ-3CNQF(4) is also an LB monolayer electrical rectifier

Metallic Conduction and Carrier Localization in Two-Dimensional BEDO-TTF Charge-Transfer Solid Crystals

Charge-transfer salts based on bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF or BO for short) provide a stable two-dimensional (2D) metallic state, while the electrical resistance often shows an upturn at low temperatures below ~10 K. Such 2D weak carrier localization was first recognized for BO salts in the Langmuir–Blodgett films fabricated with fatty acids; however, it has not been characterized in charge-transfer solid crystals. In this paper, we discuss the carrier localization of two crystalline BO charge-transfer salts with or without magnetic ions at low temperatures through the analysis of the weak negative magnetoresistance. The phase coherence lengths deduced with temperature dependence are largely dominated by the electron–electron scattering mechanism. These results indicate that the resistivity upturn at low temperatures is caused by the 2D weak localization. Disorders causing elastic scattering within the metallic domains, such as those of terminal ethylene groups, should be suppressed to prevent the localization

Metallic Conduction and Carrier Localization in Two-Dimensional BEDO-TTF Charge-Transfer Solid Crystals

Charge-transfer salts based on bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF or BO for short) provide a stable two-dimensional (2D) metallic state, while the electrical resistance often shows an upturn at low temperatures below ~10 K. Such 2D weak carrier localization was first recognized for BO salts in the Langmuir–Blodgett films fabricated with fatty acids; however, it has not been characterized in charge-transfer solid crystals. In this paper, we discuss the carrier localization of two crystalline BO charge-transfer salts with or without magnetic ions at low temperatures through the analysis of the weak negative magnetoresistance. The phase coherence lengths deduced with temperature dependence are largely dominated by the electron–electron scattering mechanism. These results indicate that the resistivity upturn at low temperatures is caused by the 2D weak localization. Disorders causing elastic scattering within the metallic domains, such as those of terminal ethylene groups, should be suppressed to prevent the localization

The Earliest Stage of Photoinduced Phase Transition in a Strongly Correlated Organic System Using a 10-fs Pulse

We examined the initial excited state before photoinduced phase transition in a charge transfer complex (EDO-TTF)2PF6 and revealed the conversion process to the photoinduced phase and the electronic coherence at the excited state