Multiexciton Solar Cells of CuInSe2 Nanocrystals.
Peak external quantum efficiencies (EQEs) of just over 120% were observed in photovoltaic (PV) devices of CuInSe2 nanocrystals prepared with a photonic curing process. The extraction of more than one electron/hole pair as a result of the absorption of a single photon can occur if multiple excitons are generated and extracted. Multiexciton generation (MEG) in the nanocrystal films was substantiated by transient absorption spectroscopy. We propose that photonic curing leads to sufficient electronic coupling between nanocrystals to enable multiexciton extraction under typical solar illumination conditions. Under low light conditions, however, the EQE drops significantly, indicating that photonic curing-induced ligand desorption creates a significant amount of traps in the film that limit the overall power conversion efficiency of the device.
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
C Jackson
CJ
Stolle
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Taylor B
TB
Harvey
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Douglas R
DR
Pernik
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Jarett I
JI
Hibbert
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Jiang
J
Du
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Dong Joon
DJ
Rhee
‡NovaCentrix, 200-B Parker Drive, Suite 580, Austin, Texas 78728, United States.
Vahid A
VA
Akhavan
§Center for Nanoscale Materials, Argonne National Laboratories, Argonne, Illinios 60439, United States.|∥Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Richard D
RD
Schaller
†McKetta Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712, United States.
Brian A
BA
Korgel
CIGS; multiple excitons; nanocrystals; photonic curing; photovoltaics; solar cells