{"56190":{"#nid":"56190","#data":{"type":"event","title":"ChBE Fall Seminar Series (October 31, 2007)","body":[{"value":"\u003Cp\u003EEric Lin of the National Institute of Standards and Technology (NIST), presents Correlating Materials Structure with Carrier Mobility in High Performance Semiconducting Polymers as part of ChBE\u0027s Fall seminar series.\n\u003C\/p\u003E\n\u003Cp\u003EABSTRACT:\u003Cbr \/\u003E\nThe microstructure of organic semiconductor films strongly affect charge carrier mobility\u003Cbr \/\u003E\nbecause it defines the persistence and quality of pi-orbital overlap in the source-drain plane.\u003Cbr \/\u003E\nImportant aspects of microstructure include the intermolecular packing arrangement within\u003Cbr \/\u003E\ncrystals, the surface-relative crystal orientation, and the overall crystal size and connectivity. We\u003Cbr \/\u003E\ncombine complementary microstructure measurements including polarized absorption\u003Cbr \/\u003E\nspectroscopies (IR, vis, and X ray), scanning probe techniques, and X-ray diffraction to\u003Cbr \/\u003E\ndetermine the microstructure of polymer semiconductors for organic thin film transistors\u003Cbr \/\u003E\n(OTFTs). Here, we demonstrate this approach by solving the packing arrangement of a polymer\u003Cbr \/\u003E\nsemiconductor, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophenes) (pBTTTs), with hole\u003Cbr \/\u003E\nmobility of (0.2 to 0.6) cm2\/Vs. Near edge X-ray absorption fine structure (NEXAFS)\u003Cbr \/\u003E\nspectroscopy indicates a conjugated plane tilt that strongly impacts electron and hole\u003Cbr \/\u003E\nbandwidths. NEXAFS combined with Fourier transform infrared spectroscopy (FTIR) reveals\u003Cbr \/\u003E\nnearly all-trans side chains that strongly tilt; reconciled with the XRD lamellar spacing it proves\u003Cbr \/\u003E\nthat vertically adjacent layers interdigitate. A general consideration of side chain configuration\u003Cbr \/\u003E\nreveals a striking signature packing motif that sets high performance polymers such as pBTTT\u003Cbr \/\u003E\napart from the lower performance poly(3 alkylthiophenes). A simple model provides a synthetic\u003Cbr \/\u003E\ndesign rule describing the side chain graft density necessary to achieve this signature packing.\n\u003C\/p\u003E\n\u003Cp\u003EUnless otherwise noted, all seminars are held in the Molecular Science and Engineering Building in Room G011. Refreshments are served at 3:30 PM. The seminar starts promptly at 4:00 PM.\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"Eric Lin of the National Institute of Standards and Technology (NIST), presents Correlating Materials Structure with Carrier Mobility in High Performance Semiconducting Polymers as part of ChBE\u0027s Fall seminar series.","format":"limited_html"}],"field_summary_sentence":[{"value":"Eric Lin presents a seminar"}],"uid":"27255","created_gmt":"2010-05-20 11:46:47","changed_gmt":"2016-10-08 01:51:37","author":"Josie Giles","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2007-10-31T16:30:00-04:00","event_time_end":"2007-10-31T18:00:00-04:00","event_time_end_last":"2007-10-31T18:00:00-04:00","gmt_time_start":"2007-10-31 20:30:00","gmt_time_end":"2007-10-31 22:00:00","gmt_time_end_last":"2007-10-31 22:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"related_links":[{"url":"http:\/\/www.chbe.gatech.edu\/","title":"School of Chemical \u0026 Biomolecular Engineering"}],"groups":[{"id":"1240","name":"School of Chemical and Biomolecular Engineering"}],"categories":[],"keywords":[{"id":"1303","name":"chbe"},{"id":"1704","name":"chemical \u0026 biomolecular engineering"},{"id":"560","name":"chemical engineering"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJosie Giles\u003C\/strong\u003E\u003Cbr \/\u003ESchool of Chemical \u0026amp; Biomolecular Engineering\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jg234\u0022\u003EContact Josie Giles\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-385-2299\u003C\/strong\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}