Marc Gurau

Mentor: Lee Richter

Surface and Microanalysis Science Division (837)

Chemical Science and Technology Laboratory

Room B143 in AML Building(217)

Mail Stop 8372, Telephone (301) 975-4305, FAX (301) 417-1321


I am not a Sigma Xi member

The category that best describes my poster: Materials Chemistry



A Combined Optical Approach to Structural Determination of Semi-Conducting Polymer Thin Films


Marc C. Gurau, Dean M. Delongchamp, Brandon Vogel, Lee J Richter



            Realization of the promise of organic electronics will requires advances in the associated materials and process chemistry along with improvements in the metrologies used to characterize the various components of such devices.  Previous work on thin films of prototypical semi-conducting polymers has demonstrated that changes in molecular weight and fabrication conditions, particularly annealing of films, can have significant effects on the performance of these films.  Yet, these investigations have yet to show good correlation between the experiments characterizing the material (AFM and X-Ray diffraction) and the observed changes in the transport properties of the films.  Transmission UV-Vis spectroscopy, Variable Angle Spectroscopic Ellipsometry (VASE), and FTIR spectroscopy were used in concert to investigate poly-3-hexyl thiophene (P3HT) films of different molecular weights, spin-cast from chloroform solution onto hydrophobic Si wafers before and after annealing of the film.  Changes in the optical absorptions of the different molecular weight polymers upon annealing confirmed previously reported changes in the structure of the polymer backbone.  Interestingly, FTIR studies showed that the changes in backbone structure occurred without significant alteration of the structure of the alkyl side chains.  In fact, the data indicates that the hexyl side chains remain disordered for films prepared from both molecular weight fractions, regardless of annealing conditions.  Finally our ongoing work to obtain a more detailed and comprehensive understanding of the structures of these systems through further analysis of the spectroscopic data is presented.