{"148211":{"#nid":"148211","#data":{"type":"event","title":"Prof. Emily Weiss, Northwestern University","body":[{"value":"\u003Cp\u003EProf. Emily Weiss, Northwestern University\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EA Molecule to Detect and Perturb the Confinement of Charge Carriers in Colloidal Quantum Dots\u003C\/strong\u003E\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003ESchool Colloquium\u003C\/p\u003E\u003Cp\u003EThis talk describes unprecedented bathochromic shifts (up to 970 meV) of the optical bandgaps of CdS, CdSe, and PbS quantum dots (QDs) upon adsorption of an organic ligand, phenyldithiocarbamate (PTC), and the use of PTC to map the quantum confinement of specific charge carriers within the QDs as a function of their radius. For a given QD material and physical radius, R, the magnitude of the increase in apparent excitonic radius (\u0394R) upon delocalization by PTC directly reflects the degree of quantum confinement of one or both charge carriers. The plots of \u0394R vs. R for CdSe and CdS show that exciton delocalization by PTC occurs specifically through the excitonic hole. Furthermore, the plot for CdSe, which spans a range of R over multiple confinement regimes for the hole, identifies the radius (R ~ 1.9 nm) at which the hole transitions between regimes of strong and intermediate confinement. Substituting the PTC molecule at the \u003Cem\u003Epara\u003C\/em\u003E position tunes the resonance between the PTC HOMO and the valence band levels of the QD.\u0026nbsp; This demonstration of ligand-induced delocalization of a \u003Cem\u003Especific\u003C\/em\u003E charge carrier is a first step toward eliminating current-limiting resistive interfaces at organic-inorganic junctions within solid-state hybrid devices.\u003C\/p\u003E\u003Cp\u003EFor more information contact \u003Ca href=\u0022mailto:seth.marder@chemistry.gatech.edu\u0022\u003EProf. Seth Marder\u003C\/a\u003E (404-385-6048).\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EProf. Emily Weiss, Northwestern University\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003E\u003Cstrong\u003EA Molecule to Detect and Perturb the Confinement of Charge Carriers in Colloidal Quantum Dots\u003C\/strong\u003E\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003ESchool Colloquium\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Prof. Emily Weiss, Northwestern University"}],"uid":"27275","created_gmt":"2012-08-21 09:30:15","changed_gmt":"2016-10-08 01:59:33","author":"Shirley Tomes","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2012-09-20T17:00:00-04:00","event_time_end":"2012-09-20T18:00:00-04:00","event_time_end_last":"2012-09-20T18:00:00-04:00","gmt_time_start":"2012-09-20 21:00:00","gmt_time_end":"2012-09-20 22:00:00","gmt_time_end_last":"2012-09-20 22:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"related_links":[{"url":"http:\/\/www.chemistry.northwestern.edu\/faculty\/emily-weiss.html","title":"Prof. Emily Weiss"}],"groups":[{"id":"85951","name":"School of Chemistry and Biochemistry"}],"categories":[],"keywords":[],"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":"\u003Cp\u003EShirley Tomes (404-894-0591) \u003Ca href=\u0022mailto:shirley.tomes@chemistry.gatech.edu\u0022\u003Eshirley.tomes@chemistry.gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}