A nano composite, a nanoparticle ink composition including a solvent and the nanocomposite, and a light-emitting device including a first electrode, a second electrode facing the first electrode, and an interlayer between the first electrode and the second electrode, wherein the interlayer includes an emission layer, and at least one layer included in the interlayer is made from the nanoparticle ink composition. The nano composite includes: a metal oxide nanoparticle; and a chelating ligand bonded to a surface of the nanoparticle and including a cyclic moiety.

An ink set including at least one first ink composition and at least one second ink composition, wherein the first ink composition contains a pigment, an inorganic oxide colloid, and water, the second ink composition contains a dye and water, and in the ink set, an arithmetic mean of a conductivity of the at least one first ink composition at 25° C. and a conductivity of the at least one second ink composition at 25° C. is 2.5 mS/cm or less.

A method of producing a coloring material dispersion is a method of producing a coloring material dispersion that contains water and a coloring material, including a polymerization step of performing a polymerization reaction in a liquid phase that contains an organic solvent containing two or more hydroxyl and/or ether groups in a molecule, a hydrophobic monomer having an aromatic ring or a (meth)acrylic acid alkyl ester structure, and a hydrophilic monomer containing a carboxylic acid group or a sulfonic acid group to synthesize a dispersion resin. The dispersion resin has a weight-average molecular weight of 5,000 or greater and less than 100,000. A content of a constituent unit A corresponding to the hydrophobic monomer in all constituent monomers contained in the dispersion resin is 50 mol % or greater.

A water-based composition of the present disclosure includes a metal pigment, a polyoxyalkylene amine compound, and a water-based medium, in which the metal pigment is formed of a plurality of metal particles, the metal particles are surface-modified by a surface treatment agent, and a content of the polyoxyalkylene amine compound is 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the metal particles.

An aqueous ink jet ink composition contains an organic solvent with an SP value of 9.5 to 10.5, resin particles, a plasticizer, and water. With respect to the amount of the aqueous ink jet ink composition, 1.0% by mass to 10.0% by mass of the organic solvent is contained.

A formulation for inkjet printing includes one or more solvents and a plurality of nanoparticles mixed with the one or more solvents. The plurality of nanoparticles has a first refractive index greater than 1.9. A method includes depositing a layer of the formulation by inkjet printing onto a substrate having a non-flat. The method thereby forms coating of the formulation having a first surface conforming to the non-flat surface of the substrate and a second surface, opposite to the first surface, being a flat surface. An optical device includes a surface relief grating and a coating layer disposed on the surface relief grating. The coating layer includes a plurality of nanoparticles having a refractive index greater than 1.45 and a resin. The plurality of nanoparticles has functional ligands cross-linked with the resin.

An ink composition includes: a solvent; and an electron transporting material substantially dispersed in the solvent and of Formula 1, wherein the ink composition has an Ohnesorge number of about 0.1 to about 0.2:

[Ar.sub.1].sub.b1-[(L.sub.1).sub.a1-R.sub.1].sub.c1  Formula 1

wherein the variables are defined herein.

An ink composition including: a first multifunctional monomer including two or more photo-functional groups and a first carbon-containing chain; a second monofunctional monomer including one photo-functional group and a second carbon-containing chain; and semiconductor nanoparticles, wherein the first carbon-containing chain and the second carbon-containing chain each independently contain an alkyl group, and the number of carbons in the second carbon-containing chain is less than the number of carbons in the first carbon-containing chain. A film formed using the ink composition, and an electronic apparatus including the film.

An ink composition including: a first multifunctional monomer including two or more photo-functional groups and a first carbon-containing chain; a second monofunctional monomer including one photo-functional group and a second carbon-containing chain; and semiconductor nanoparticles, wherein the first carbon-containing chain and the second carbon-containing chain each independently contain an alkyl group, and the number of carbons in the second carbon-containing chain is less than the number of carbons in the first carbon-containing chain. A film formed using the ink composition, and an electronic apparatus including the film.

A nanoparticle ink composition includes: a solvent; and one or more inorganic nanoparticles substantially dispersed in the solvent, wherein the inorganic nanoparticles include one or more quantum dots or a metal oxide having a diameter of about 20 nm or less, and the nanoparticle ink composition has an Ohnesorge number of about 0.1 to about 0.2.