5′-(Anthracene-9,10-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene) derivatives bearing 5-ethynyl-5′-hexyl-2,2′-bithiophene and 2-ethynyl-5-hexylthieno[3,2-b]thiophene: Thin film transistors and photovoltaic applications

Novel 5,5′-(anthracene-9,10-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene)-based conjugated molecules have been synthesized via the Sonogashira coupling reaction. Newly synthesized anthracene-based molecules exhibit good solubility in common organic solvents and good self-film-forming properties. The semiconducting properties of the two molecules were evaluated in organic thin film transistors (OTFTs). The two π-conjugated molecules 4 and 7 exhibit fairly high charge carrier mobilities—as high as 0.010–0.022 cm² V^?1 s^?1 (I_on/I_off > 10³)—without any annealing process. The high charge carrier mobilities of the as-spun films are attributed to the fact that the molecules demonstrated pronounced J-aggregation behavior, resulting in easy crystallization and dense coverage of the surface of a dielectric layer. In addition, two molecules were employed to fabricate organic photovoltaic (OPV) cells with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PC₆₁BM) without thermal annealing. As a result, the photovoltaic cell containing 7 had the best preliminary results with an open-circuit voltage of 0.92 V, a short-circuit current density of 1.82 mA/cm², and a fill factor of 0.32, offering an overall power conversion efficiency (PCE) of 0.54%.     

Electrical conductivity and molecular properties of organodithioheterobimetallics [PhHg]2[M(dithio)2] {M=Ni, Cu or Zn; dithio=isomaleonitriledithiolate (i-MNT) 1,1-dicarboethoxy-2,2-ethylenedithiolate (DED) or trithiocarbonate (CS3)}

Organoheterobimetallic compounds of the type, [PhHg]₂[M(dithio)₂] {M=Ni(II), Cu(II) or Zn(II); dithio=isomaleonitriledithiolate (i-MNT²⁻), 1,1-dicarboethoxy-2,2-ethylenedithiolate (DED²⁻) or trithiocarbonate (CS₃²⁻)} have been synthesized and investigated by molecular spectroscopies and conductivity techniques. Magnetic behaviour, together with electronic spectra, are compatible with square planar coordination geometry around nickel(II) in [PhHg]₂[Ni(dithio)₂]. Magnetic moments, 1.6 BM and 1.25 BM for [PhHg]₂[Cu(i-MNT)₂] and [PhHg]₂[Cu(DED)₂] showed involvement of some sort of Cu–Cu interaction. Their electronic and EPR spectra show distorted square planar geometry with tetragonal/rhombic symmetry around copper(II). Powder X-ray diffraction patterns of the complexes have been compared. All the complexes show σ_rt in 2.29×10⁻¹⁰−4.38×10⁻⁴ S cm⁻¹ range. [PhHg]₂[Ni(DED)₂] and [PhHg]₂[Cu(i-MNT)₂] show semiconducting behaviour as their conductivity increases with increase in temperature with band gaps 0.39 eV; 0.57 eV and 2.38 eV, respectively.