Role of PbSe Structural Stabilization in Photovoltaic Cells

Semiconductor nanocrystals are promising materials for printed optoelectronic devices, but their high surface areas are susceptible to forming defects that hinder charge carrier transport. Furthermore, correlation of chalcogenide nanocrystal (NC) material properties with solar cell operation is not...

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Bibliographic Details
Published in:Advanced functional materials 2015-02, Vol.25 (6), p.928-935
Main Authors: Asil, Demet, Walker, Brian J., Ehrler, Bruno, Vaynzof, Yana, Sepe, Alessandro, Bayliss, Sam, Sadhanala, Aditya, Chow, Philip C. Y., Hopkinson, Paul E., Steiner, Ullrich, Greenham, Neil C., Friend, Richard H.
Format: Article
Language:English
Subjects:
Architecture
Halides
Nanocrystals
Order disorder
organic electronics
Passivation
Photovoltaic cells
photovoltaic devices
quantum dots
Semiconductors
Solar cells
Symmetry
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Summary:Semiconductor nanocrystals are promising materials for printed optoelectronic devices, but their high surface areas are susceptible to forming defects that hinder charge carrier transport. Furthermore, correlation of chalcogenide nanocrystal (NC) material properties with solar cell operation is not straightforward due to the disorder often induced into NC films during processing. Here, an improvement in long‐range ordering of PbSe NCs symmetry that results from halide surface passivation is described, and the effects on chemical, optical, and photovoltaic device properties are investigated. Notably, this passivation method leads to a nanometer‐scale rearrangement of PbSe NCs during ligand exchange, improving the long‐range ordering of nanocrystal symmetry entirely with inorganic surface chemistry. Solar cells constructed with a variety of architectures show varying improvement and suggest that triplet formation and ionization, rather than carrier transport, is the limiting factor in singlet fission solar cells. Compared to existing protocols, our synthesis leads to PbSe nanocrystals with surface‐bound chloride ions, reduced sub‐bandgap absorption and robust materials and devices that retain performance characteristics many hours longer than their unpassivated counterparts. Inorganic treatment of nanocrystals removes traps, increases long‐range ordering of the symmetry, and improves stability in solar cells. A combination of optical, electronic, and material characterization tools demonstrates that chloride treatment confers many benefits on photovoltaic materials.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201401816