Preparation and Characterization of the Disjoint Diradical 4,4‘-Bis(1,2,3,5-dithiadiazolyl) [S₂N₂C−CN₂S₂] and Its Iodine Charge Transfer Salt [S₂N₂C−CN₂S₂][I]

Abstract

Preparation and characterization of the disjoint diradical 4,4'-bis(1,2,3,5-dithiadiazolyl) [S2N2C-CN2S2] and its iodine charge transfer salt [S2N2C-CN2S2] Bryan, C.D.; Cordes, A.W.; Goddard, J.D.; Haddon, R.C.; Hicks, R.G.; MacKinnon, C.D.; Mawhinney, R.C.; Oakley, R.T.; Palstra, T.T.M.; Perel, A.S.

Anomalous Transient Photocurrent

“…3) and current-voltage (J-V) characteristics were recorded. BDTDA was prepared as described in a previous report (Bryan et al, 1996), and was thermally evaporated onto ITO glasses. As a top electrode, Al was also thermally evaporated onto the thin films.…”

“…Though such anomalous photocurrent, or photoinduced displacement current, has received previous attention (Andriesh et al, 1983;Chakraborty & Mallik, 2009;Iwamoto, 1996;Kumar et al, 1987;Sugimura et al, 1989;Tahira & Kao, 1985), its mechanism and characteristics are still largely unresolved. We systematically explained this phenomenon based on our theoretic analyses and experiments on an organic radical 4'4-bis(1,2,3,5-dithiadiazolyl) (BDTDA) (Bryan et al, 1996) thin film device. A double-layer model was introduced, and a new type of device with structure of metal/blocking layer/semiconductor layer/metal was developed to reproduce the anomalous photocurrent (Hu et al, 2010b).…”

The Synthesis and Characterization of Stable Radicals Containing the Thiazyl (SN) Fragment and Their Use as Building Blocks for Advanced Functional Materials

“…134 Similarly, the dithiadiazolyl diradical 39, which has "no" substituent, is one of the few dithiadiazolyl radicals with measurable conductivity. 121,122 Both of these radical derivatives have π stacks of cofacial π dimers as well as extensive interstack contacts.…”

“…Iodine charge transfer salts of other dithia-and diselenadiazolyl diradicals include those based on the 1,4-(148, 150) and 1,3-phenylene (149, 151) linked diradicals, 228,229 heterocyclic (152, 153, 154) spacers, 230,231 and the diradical 39 with the two dithiadiazolyls directly attached to one another. 122 The selenium-based systems are made by electrochemical reduction of the corresponding dications in the presence of iodine, because the diselenadiazolyl diradicals are too involatile for the cosublimation chemistry to work. The structure and electronic properties of [148][I] are qualitatively reproduced in the iodide charge transfer salts of 149-155, that is, regularly spaced π stacks alongside disordered polyiodide channels, high (>10 S/cm) room temperature conductivities, and metal-insulator transitions between 200 and 270 K. Band structure calculations suggest conduction bandwidths of 3-4 eV, based largely on the "perfect" π stacked structures (i.e., interstack interactions are, in a relative sense, far less significant in these materials).…”

“…The electronic state energetics of diradical 39, 121 in which the two CN 2 S 2 rings are directly attached to one another at the carbon atoms, have been investigated using computational methods. 122 The aforementioned nodal plane present in the dithiadiazolyl SOMO (38) prevents direct (conjugative) coupling of the spins. As such, 39 has two halffilled molecular orbitals 40a and 40b, which are simply the linear combinations of the SOMOs on each ring.…”