Tuning of the Photovoltaic Parameters of Molecular Donors by Covalent Bridging

The synthesis of donor-acceptor molecules involving triarylamines and dicyanovinyl blocks is described. Optical and electrochemical results show that rigidification of the acceptor part of the molecule by a covalent bridge leads to a ca. 0.20 eV increase of the band gap due to a parallel increase of the lowest unoccupied molecular orbital level. A preliminary evaluation of these compounds as donor materials in organic solar cells shows that although this structural modification reduces the light-harvesting properties of the donor molecule, it nevertheless induces an increase of the efficiency of the resulting solar cells due to a simultaneous improvement of the open-circuit voltage and fill factor

Psychometric properties of the transaddiction craving triggers questionnaire in alcohol use disorder.

We aimed to develop the transaddiction craving triggers questionnaire (TCTQ), which assesses the propensity of specific situations and contexts to trigger craving and to test its psychometric properties in alcohol use disorder (AUD). This study included a sample of 111 AUD outpatients. We performed exploratory factor analysis (EFA) and calculated item-dimension correlations. Internal consistency was measured with Cronbach's alpha coefficient. Construct validity was assessed through Spearman correlations with craving, emotional symptoms, impulsivity, mindfulness, and drinking characteristics. The EFA suggested a 3-factor solution: unpleasant affect, pleasant affect, and cues and related thoughts. Cronbach's coefficient alpha ranged from .80 to .95 for the three factors and the total score. Weak positive correlations were identified between the TCTQ and drinking outcomes, and moderate correlation were found between the TCTQ and craving strength, impulsivity, anxiety, depression, and impact of alcohol on quality of life. The 3-factor structure is congruent with the well-established propensity of emotions and cues to trigger craving. Construct validity is supported by close relations between the TCTQ and psychological well-being rather than between the TCTQ and drinking behaviors. Longitudinal validation is warranted to assess sensitivity to change of the TCTQ and to explore its psychometric properties in other addictive disorders

Electric-Field-Induced Mott Insulating States in Organic Field-Effect Transistors

We consider the possibility that the electrons injected into organic field-effect transistors are strongly correlated. A single layer of acenes can be modelled by a Hubbard Hamiltonian similar to that used for the kappa-(BEDT-TTF)(2)X family of organic superconductors. The injected electrons do not necessarily undergo a transition to a Mott insulator state as they would in bulk crystals when the system is half-filled. We calculate the fillings needed for obtaining insulating states in the framework of the slave-boson theory and in the limit of large Hubbard repulsion, U. We also suggest that these Mott states are unstable above some critical interlayer coupling or long-range Coulomb interaction.Comment: 9 pages, 7 figure

Polarizability and Internal Charge Transfer in Thiophene-Triphenylamine Hybrid pi-Conjugated Systems

Extended star-shaped conjugated systems consisting of dicyanovinyl electron-acceptor units connected to a triphe-nylamine core by means of thiophene (T), thienylenevinylene (TV), and bithiophene (BT) conjugating spacers have been synthesized. The analysis of the electronic properties of the molecules by UV-vis absorption spectroscopy, cyclic voltammetry, and theoretical calculations shows that the electronic properties of the systems depend on the length and rigidity of the conjugating spacer

Ultrafast Pump-Push Photocurrent Spectroscopy of Organic Photoconversion Systems

Novel optical pump-push – photocurrent probe ultrafast spectroscopy experiments on organic photoconversion systems show that excessive excitation energy in such systems is not lost but used to reach delocalised states that act as the gateway for long-range charge separation. We also show that the developed experimental approach can be generalised to inorganic and hybrid photoconversion systems

A New Photomechanical Molecular Switch Based on a Linear {\pi}-Conjugated System

We report the electronic transport properties of a new photo-addressable molecular switch. The switching process relies on a new concept based on linear {\pi}-conjugated dynamic systems, in which the geometry and hence the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans-cis isomerization of an azobenzene unit fixed in a lateral loop. Electron transport measurements through self-assembled monolayers on gold, contacted with eGaIn top contact, show switching with a conductance ratio up to 1E3. Ab initio calculations have been used to identify the most energetically stable conformations of the molecular switch, the corresponding calculated conductances qualitatively explain the trend observed in the photo-switching experiments.Comment: Full manuscript and supporting information, J. Phys. Chem. C,published on line (2017

A New Photomechanical Molecular Switch Based on a Linear {\pi}-Conjugated System

We report the electronic transport properties of a new photo-addressable molecular switch. The switching process relies on a new concept based on linear {\pi}-conjugated dynamic systems, in which the geometry and hence the electronic properties of an oligothiophene chain can be reversibly modified by the photochemical trans-cis isomerization of an azobenzene unit fixed in a lateral loop. Electron transport measurements through self-assembled monolayers on gold, contacted with eGaIn top contact, show switching with a conductance ratio up to 1E3. Ab initio calculations have been used to identify the most energetically stable conformations of the molecular switch, the corresponding calculated conductances qualitatively explain the trend observed in the photo-switching experiments.Comment: Full manuscript and supporting information, J. Phys. Chem. C,published on line (2017