Metal Halide Solid-State Surface Treatment for High Efficiency PbS and PbSe QD Solar Cells

We developed a layer-by-layer method of preparing PbE (E = S or Se) quantum dot (QD) solar cells using metal halide (PbI 2 , PbCl 2 , CdI 2 , or CdCl 2 ) salts dissolved in dimethylformamide to displace oleate surface ligands and form conductive QD solids. The resulting QD solids have a significant...

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Bibliographic Details
Published in:Scientific reports 2015-04, Vol.5 (1), p.9945-9945, Article 9945
Main Authors: Crisp, Ryan W., Kroupa, Daniel M., Marshall, Ashley R., Miller, Elisa M., Zhang, Jianbing, Beard, Matthew C., Luther, Joseph M.
Format: Article
Language:English
Subjects:
140/146
639/301/299/946
639/925/357/1017
Chlorides
Dimethylformamide
Halides
Humanities and Social Sciences
ligand exchange
Ligands
multidisciplinary
nanocrystals
NANOSCIENCE AND NANOTECHNOLOGY
Photovoltaic cells
Quantum dots
quantum dots (QD)
Salts
Science
Solar cells
SOLAR ENERGY
Thiols
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Summary:We developed a layer-by-layer method of preparing PbE (E = S or Se) quantum dot (QD) solar cells using metal halide (PbI 2 , PbCl 2 , CdI 2 , or CdCl 2 ) salts dissolved in dimethylformamide to displace oleate surface ligands and form conductive QD solids. The resulting QD solids have a significant reduction in the carbon content compared to films treated with thiols and organic halides. We find that the PbI 2 treatment is the most successful in removing alkyl surface ligands and also replaces most surface bound Cl - with I - . The treatment protocol results in PbS QD films exhibiting a deeper work function and band positions than other ligand exchanges reported previously. The method developed here produces solar cells that perform well even at film thicknesses approaching a micron, indicating improved carrier transport in the QD films. We demonstrate QD solar cells based on PbI 2 with power conversion efficiencies above 7%.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep09945