Structural Characterization of a Functionalized Organic Semiconductor
- PDF / 171,533 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 57 Downloads / 214 Views
I3.16.1
Structural Characterization of a Functionalized Organic Semiconductor Melissa Stickle1, Refik Kortan, Sandrine Rivillon2, Zhenan Bao3, Howard Katz4, Yves Chabal1,2 Biomedical Engineering, Rutgers University, Piscataway, NJ 08823 U.S.A. 2 Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08823 U.S.A. 3 Chemical Engineering, Stanford University, Stanford, CA 94305 U.S.A. 4 Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 U.S.A. 1
ABSTRACT We report the structure of 5,5’-bis(4-hydroxyhexylphenyl)-2,2’-bithiophene (HO6PTTP6OH) powder and sublimated films studied by X-ray diffraction (XRD) and Infrared absorption spectroscopy (IRAS). From XRD, herringbone packing is observed for the HO6PTTP6OH powder. Different layer spacing is found for the powder (33.1Å) and the sublimated film (26.5Å). This slight difference indicates that the HO6PTTP6OH molecule is tilted in the film. IRAS results confirm the presence of the HO6PTTP6OH molecule on the surface and its good stability over a few days. INTRODUCTION Organic materials utilizing phenyl and thiophene aromatic groups have been shown as successful semiconducting layers in organic field effect transistors. Studies on the effects of terminal alkyl substitutions on aromatic molecular orientation and field effect mobility have demonstrated that terminal hexyl substitutions enhance long-range order [1]. The improved ordering of αωDH6T through induced self assembly properties was correlated to increased field effect mobility over an unsubstituted sexithiophene and was in part attributed to the segregation of flexible alkyl chains from rigid sexithiophene core groups [1]. We investigate the molecular packing and morphology of a similar molecule containing a bithiophene core, and hexanol termination. We anticipate a similar segregation and enhanced self-assembly due to the rigid πconjugated aromatic core and flexible hexanol termination, however the effects of polar hydroxyl termination on molecular structure is of interest for future surface functionalization for sensing applications [2]. Mushrush [3] explored the combination of adding hexyl termination to phenylene-thiophene oligomers in various ratios and arrangements with alkyl terminal groups. Solution processing and thermal stability of phenylene-thiophene oligomers demonstrated by Mushrush [3] and Katz [4] motivate a prerequisite characterization of the effects of functionalization on film morphology and conductivity for sensing applications [5,6]. We have studied the structure of 5,5’-bis(4-hydroxyhexylphenyl)-2,2’-bithiophene (HO6PTTP6OH) powder and sublimated films studied using X-ray diffraction (XRD) and Infrared absorption spectroscopy (IRAS). Powder spectra are used to assign a unit cell, index Bragg peaks, and determine the molecular ordering that takes place within the unit cell. In order to evaluate film ordering, bonding, and stability, we deposit thin films of organic molecules on an insulating silicon dioxide layer using high vacuum sublimation. Diffraction
Data Loading...
