Our primary area is concerned with the synthesis and characterization of novel polymeric materials for application in devices, such as light-emitting diodes (LEDs), field effect transistors (FETs), and excitonic solar cells (XSC). Semi-empirical MO methods and molecular mechanics are used to predict or explain observed structures, reaction patterns, or spectral properties. Polymers are characterized by a variety of techniques, including UV-Vis-NIR, CV, FT-NMR, GPC, TGA-DSC, WAXS, and electron microscopy. Doped polymers are characterized by conductivity measurements and spectroelectrochemistry as well as the more usual techniques.
Recently, we synthesized a new class of conjugated polymer, the poly(4,4'-dialkyl-2,2'-bithiazole-5,5' -diyl)s (a.k.a. poly(alkylbithiazoles) or PABTs). These polymers are related to poly(thiophenes) but have one ring -CH groups replaced by a N-atom. The more electronegative N-atom imparts unusual properties to the polymer as evidenced by stronger, pi-stacking and S...S contacts between polymer chains.
We have now synthesized new "co-oligomers" that incorporate ethylenedioxythiopene (EDDT) and bithiuzole units into the main chain. These new compounds have the pi-stacked structures typical of the bithiazoles and the stability toward p-doping characteristic of EDOT. These materials exhibit very high carrier mobilities in thin film transitors (TFTs).
This research is highly collaborative. Professor D.C. Martin (Materials Science and Engineering) determines solid state morphologies and their role in device optimization. Professor L. J. Guo (Electrical Engineering) designs and characterizes devices based on the polymers. Professor A. Francis (Chemistry) directs research on optical and electrical properties and on energy transport in the polymer thin films.
"Synthesis and Characterization of Regioregular and Regiorandom Poly(3-Octylfuran)", JK Politis, J. Nemes, MD Curtis J. Am. Chem. Soc. 2001, 123, 2537.
"Sequence Length Distributions (Microstructure) of Regioregular Poly(3-alkylthiphene)s and Their Use in Simulating pi-pi* Absorption Peak Profiles", MD Curtis Macromolecules 2001, 34, 7905.
"Charge Transfer in Ferrocene-Bearing Poly(thiophene)s and Application in Organic Bilayer Photocells", T Li; MD Curtis; AH Francis Macromolecules 2002, 35, 4628.
"Synthesis and characterization of bis(3,4-ethylene-dioxythiophene)-(4,4 '-dialkyl-2,2 '-bithiazole) co-oligomers for electronic applications", J Cao: JW Kampf; MD Curtis Chem. Mater. 2003, 15, 404.
"Intermolecular interactions in p-Stacked Conjugated Molecules. Synthesis, Structures, and Spectral Characterization Alkyl Bithiazole oligomers", AB Koren; MD Curtis; AH Francis; JW Kampf J. Am. Chem. Soc. 2003, 125, 5040-5050.
"Characterization of Organic p/n Junction Photodiodes based on Poly(3-alkylthiophene)/Perylene Diimide Bilayers" T Li; MD Curtis; AH Francis Chem. Mater. 2003, 15, 2272.
"Polarons, Bipolarons, and pi-Dimers of Bis(3,4-ethylenedioxythiophene)-(4,4'-dialkyl-2,2'-bithiazole)-co-Oligomers. Direct measure of the Intermolecular Exciton Transfer Interaction." J Cao; MD Curtis Chem. Mater. 2003, 15, 4424.