Date of Award
Program or Major
Doctor of Philosophy
GLEN P MILLER
The desire for portable, flexible and affordable electronic devices provides the driving force for the development of new organic semiconductors. Organic semiconductors can be solution processed, potentially enabling high-rate fabrication of electronic devices on flexible substrates. Devices of interest include organic field effect transistors (OFETs), organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). Research presented here has focused on the synthesis and characterization of three different classes of organic semiconductors: a water soluble pentacene, a disulfide-linked pentacene oligomer and several fullerene-pentacene adducts. In addition, an aromatization reaction leading to bis(organothio)pentacenes has been systematically studied.
The first water soluble pentacene, potassium 3,3'-(pentacene-6,13-diylbis(sulfanediyl)) dipropanoate (28), has been successfully synthesized and characterized. With an optical HOMO-LUMO gap of approximately 1.91-1.97 eV, indicated by UV-vis spectra in several different solvents, water soluble pentacene was utilized as donor in an active bi-layer photovoltaic cell with C60 as acceptor.
Both unsubstituted and t-butylphenyl substituted versions of 6,13-diacetylthiopentacene have been successfully synthesized and characterized as precursors to 6,13-dimercaptopentacene. An attempted synthesis of 6,13-dithiopentacene oligomers from 6,13-dimercaptopentacene appears to have been successful. However, due to poor solubility, purification and characterizations are limited.
The Diels-Alder reaction between 5,7,12,14-tetraphenylpentacene (TTP) and fullerene to generate mono- and multi- adducts has been studied both experimentally and computationally. A mono-TPP-C60 adduct, two regioisomers of a bis-TPP-C60 adduct, and a symmetric tetrakis-TPP-C60 adduct have been formed. Moreover, the shape-controlled preparation of nano- and microstructures from the mono-C60-TPP adduct have been demonstrated by judicious self-assembly in various solvent systems.
Numerous dihydropentacenes have been prepared using a ZnI2-mediated reaction between 6,13-dihydrodioxypentacene and organic thiols. The dehydrogenative aromatization of these dihydropentacenes using p-chloranil has been systematically explored. Both syn- and anti- dihydropentacene isomers are observed to form in the ZnI2 reaction, and each has been taken forward to react with p-chloranil. These aromatization reactions have been monitored using 1H NMR spectroscopy.
Li, Yushu, "SYNTHESES AND CHARACTERIZATIONS OF NOVEL ORGANIC SEMICONDUCTORS" (2014). Doctoral Dissertations. 2174.