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AssigneeQd Solar Inc.
InventorsYounghoon Kim, Fanglin Che, Jea Woong Jo, Jongmin Choi, Francisco Pelayo Garcia De Arquer, Sjoerd Hoogland, Edward H. Sargent
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The present disclosure provides a method for facet-selective passivation on each crystal facet of colloidal nanocrystals via solution-phase ligand exchange process, thereby providing highly-passivated and colloidally-stable nanocrystal inks. This ligand exchange strategy separately addresses polar and non-polar facets precluding from deleterious nanocrystal aggregation in the colloid. The method involves the introduction of alkali metal organic complexes during metal halide conventional solution exchanges, and one specific example is Na+·Ac−. Alkali metal ions stabilize and passivate non polar facets whereas polar facets are passivated through metal halides. This strategy leads to a significant decrease in nanocrystal aggregation during and after ligand exchange, and to improved photophysical properties stemming from this. The resulting nanocrystal solid films exhibit improved stability, retain their absorption features, and have a minimized Stokes shift.
A dual-passivated colloidal nanocrystal comprising at least two distinct classes of crystal facets exposed at an outer surface thereof, wherein a first class of crystal facets is substantially nonpolar, and wherein a second class of crystal facets is polar, wherein the substantially nonpolar facet is passivated by an alkali metal and the polar facet passivated by at least one halide.
Dependencies are inferred from the claim text.