Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime
Kemp, Kyle W.
Ip, Alexander H.
Thon, Susanna M.
Sargent, Edward H.
KAUST Grant NumberKUS-11-009-21
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Abstract© 2014 Macmillan Publishers Limited. Colloidal quantum dots are attractive materials for efficient, low-cost and facile implementation of solution-processed optoelectronic devices. Despite impressive mobilities (1-30 cm2V-1 s-1) reported for new classes of quantum dot solids, it is-surprisingly-the much lower-mobility (10-3-10-2 cm2V-1 s-1) solids that have produced the best photovoltaic performance. Here we show that it is not mobility, but instead the average spacing among recombination centres that governs the diffusion length of charges in today's quantum dot solids. In this regime, colloidal quantum dot films do not benefit from further improvements in charge carrier mobility. We develop a device model that accurately predicts the thickness dependence and diffusion length dependence of devices. Direct diffusion length measurements suggest the solid-state ligand exchange procedure as a potential origin of the detrimental recombination centres. We then present a novel avenue for in-solution passivation with tightly bound chlorothiols that retain passivation from solution to film, achieving an 8.5% power conversion efficiency.
CitationZhitomirsky D, Voznyy O, Levina L, Hoogland S, Kemp KW, et al. (2014) Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime. Nat Comms 5. Available: http://dx.doi.org/10.1038/ncomms4803.
SponsorsThis publication is based in part on work supported by Award KUS-11-009-21, made by King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund Research Excellence Program and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. D.Z. acknowledges his NSERC CGS D scholarship. We thank Angstrom Engineering Inc. and Innovative Technology Inc. for useful discussions regarding material deposition methods and control of the glovebox environment, respectively. We also acknowledge the technical assistance from E Palmiano, R Wolowiec and D Kopilovic.
CollectionsPublications Acknowledging KAUST Support
Except where otherwise noted, this item's license is described as Open access articles are published under a CC BY license (Creative Commons Attribution 4.0 International License).
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