The 914th Meeting of the Northeastern Section of the American Chemical Society

Apr 14, 2011
Pfizer Lecture Hall (MB23), Ground Floor, Mallinckrodt Building, Harvard Universdity, 12 Oxford Street, Cambridge, Massachusetts

Meeting in celebration of the International Year of Chemistry

5:30 p.m.  Social Hour at Harvard Faculty Club, 20 Quincy Street, Cambridge, MA

6:30 p.m.  Dinner at Harvard Faculty Club

8:15 p.m.  Esselen Award Meeting at Mallinckrodt Building

Patrick Gordon, NESACS Chair, presiding

Welcome - Dr. Arthur Obermayer, Chair, Esselen Award Committee

The Esselen Award - Dr. Myron S. Simon, Founding Member of the Esselen Award Committee

Introduction of the Award Recipient - Dr. James T. Hynes, Professor of Chemistry and Biochemistry, University of Colorado, Boulder and CNRS Director of Research Emeritus, Ecole Normale Superieure, Paris.

Presentation of the Award - Gustavus J. Esselen, IV

Award Address - Prospects and Novel Approaches for the Low Cost Power Conversion of Solar Photons to Electricity and Solar Fuels
Dr. Arthur J. Nozik, Senior Research Fellow, National
Renewable Energy Laboratory and Adjunct Professor, Department
of Chemistry and Biochemistry, University of Colorado, Boulder

Abstract: One potential, long-term approach to more efficient future (3rd) generation
solar cells for producing both electricity via photovoltaic (PV) cells and solar fuels via solar photoelectrochemical cells is to utilize the unique properties of semiconductor quantum dots (QDs) and unique molecular chromophores to control the relaxation pathways of excited states to produce enhanced conversion efficiency through efficient multiple electron-hole pair generation from absorbed single photons.  We have observed efficient multiple exciton generation (MEG) in PbSe, PbS, PbTe, and Si QDs and efficient singlet fission (SF) in molecules that satisfy specific requirements for
their excited state energy level structure.  We have studied MEG in closepacked QD arrays where the QDs are electronically coupled in the films and thus exhibit good transport.  We have developed simple, all-inorganic and potentially inexpensive QD PV solar cells based on QD arrays that produce large short-circuit photocurrents and
initial power conversion efficiencies above 5% via nanocrystalline p-n junctions.  We have observed very efficient SF in thin films of molecular crystals of1,3- diphenylisobenzofuran with quantum yields of 200%, reflecting the creation of two excited triplet states from the first excited singlet state. Various possible configurations for novel solar cells based on MEG in QDs and SF in molecules that could produce high conversion efficiencies at low cost will be presented, along with progress in developing such new types of solar cells.  Recent analyses of the interesting effect of concentrated solar irradiance on the conversion efficiency of PV and water-splitting cells (to produce hydrogen fuel) will be discussed.

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