| AVS 57th International Symposium & Exhibition | |
| Energy Frontiers Topical Conference | Monday Sessions |
| Session EN-MoA |
| Session: | Excitonic and Third Generation Solar Cells |
| Presenter: | A.J. Nozik, National Renewable Energy Lab and Univ. of Colorado, Boulder |
| Authors: | A.J. Nozik, National Renewable Energy Lab and Univ. of Colorado, Boulder M.C. Beard, National Renewable Energy Lab J.M. Luther, National Renewable Energy Lab A.G. Midgett, Univ. of Colorado, Boulder O.E. Semonin, Univ. of Colorado, Boulder J.C. Johnson, National Renewable Energy Lab |
| Correspondent: | Click to Email |
One potential, long-term approach to more efficient future generation solar cells is to utilize the unique properties of quantum dot (QD) nanostructures to control the relaxation pathways of excited QD states to produce enhanced conversion efficiency through efficient multiple exciton generation (MEG) in QDs.
We have observed efficient multiple exciton generation (MEG) in PbSe, PbS, PbTe, and Si QDs at threshold photon energies of 2-3 times the HOMO-LUMO transition. We have studied MEG in close-packed QD arrays where the QDs are electronically coupled in the films and thus exhibit good carrier mobility. We have developed simple, all-inorganic QD solar cells that produce large short-circuit photocurrents via both nanocrystalline Schottky junctions and nanocrystalline p-n junctions without the need for QD sintering, superlattice order or separate phases for electron and hole transport. The latter shows an NREL-Certified conversion efficiency of 3%. We have demonstrated that the MEG efficiency in conductive Pb chalcogenide QD films after certain chemical treatments can be comparable to isolated QDs in colloids, but the QY varies greatly depending upon the specific chemical treatment. and subsequent QD surface chemistry.
Selected aspects of this work will be summarized and recent advances will be discussed. Various possible configurations for novel QD solar cells that could produce very high conversion efficiencies will be presented, along with progress in developing such new types of solar cells. Recent controversy about MEG and its application to photovoltaic cells will also be addressed.