A semiconductor film contains aggregates of semiconductor quantum dots containing a metal atom and a ligand that is coordinated to the semiconductor quantum dot, where the ligand contains a first ligand that is an inorganic halide and a second ligand that is represented by any one of Formulae (A) to (C). X.sup.A1 and X.sup.A2 are separated by L.sup.A1 by 1 or 2 atoms, X.sup.B1 and X.sup.B3, and X.sup.B2 and X.sup.B3 are respectively independently separated by L.sup.B1 and L.sup.B2 by 1 or 2 atoms, and X.sup.C1 and X.sup.C4, X.sup.C2 and X.sup.C4, and X.sup.C3 and X.sup.C4 are respectively independently separated by L.sup.C1, L.sup.C2, or L.sup.C3 by 1 or 2 atoms.

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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.sup.+.Ac.sup.−. 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.

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.sup.+.Ac.sup.−. 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.

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.sup.+.Math.Ac.sup.−. 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.

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.sup.+.Math.Ac.sup.−. 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.

The present disclosure is a photoelectric conversion element including: a photoelectric conversion layer 5 including a first quantum dot 4a and a second quantum dot 4b, a ratio X of the number of heavy metal atoms to the number of oxygen group atoms is less than 2 on a surface of the nanoparticle of the first quantum dot 4a, the ratio X is greater than or equal to 2 on a surface of the nanoparticle of the second quantum dot 4b, and Equation (1) is satisfied:

0.3<N(1),

where N denotes a ratio of the number of second quantum dots to the number of first quantum dots.

The present disclosure is a photoelectric conversion element including: a photoelectric conversion layer 5 including a first quantum dot 4a and a second quantum dot 4b, a ratio X of the number of heavy metal atoms to the number of oxygen group atoms is less than 2 on a surface of the nanoparticle of the first quantum dot 4a, the ratio X is greater than or equal to 2 on a surface of the nanoparticle of the second quantum dot 4b, and Equation (1) is satisfied:

0.3<N(1),

where N denotes a ratio of the number of second quantum dots to the number of first quantum dots.

Highly ordered arrays of 3D faceted nanoparticle supercrystals are formed by self-assembly with controlled nanoparticle packing and unique facet dependent optical property by using a binary solvent diffusion method. The binary diffusion results in supercrystals whose size and quality are determined by initial nanoparticle concentration and diffusion speed. The supercrystal solids display unique facet-dependent surface plasmonic and surface-enhanced Raman characteristics. The supercrystals have potential applications in areas such as optics, electronics, and sensor platforms.

Highly ordered arrays of 3D faceted nanoparticle supercrystals are formed by self-assembly with controlled nanoparticle packing and unique facet dependent optical property by using a binary solvent diffusion method. The binary diffusion results in supercrystals whose size and quality are determined by initial nanoparticle concentration and diffusion speed. The supercrystal solids display unique facet-dependent surface plasmonic and surface-enhanced Raman characteristics. The supercrystals have potential applications in areas such as optics, electronics, and sensor platforms.

A continuous flow reactor for the efficient synthesis of nanoparticles with a high degree of crystallinity, uniform particle size, and homogenous stoichiometry throughout the crystal is described. Disclosed embodiments include a flow reactor with an energy source for rapid nucleation of the .[.procurors following.]. .Iadd.precursors to form nucleates followed .Iaddend.by a separate heating source for growing the nucleates. Segmented flow may be provided to facilitate mixing and uniform energy absorption of the precursors, and post production quality testing in communication with a control system allow automatic real-time adjustment of the production parameters. The nucleation energy source can be monomodal, multimodal, or multivariable frequency microwave energy and tuned to allow different precursors to nucleate at substantially the same time thereby resulting in a substantially homogenous nanoparticle. A shell application system may also be provided to allow one or more shell layers to be formed onto each nanoparticle.