Crosslinked ligands

1. An optical medium comprising a semiconducting light emitting nanoparticle comprising

a core,

one or more shell layers, and

a polymeric outer layer,

at least one organic ligand A, at least one organic ligand B and at least one organic ligand C attached to the outermost surface of the shell layers,

wherein

the polymeric outer layer is formed by direct linkages between the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C through crosslinking functional group X on the at least one organic ligand A,

crosslinking functional group Y on the at least one organic ligand B, and crosslinking functional group Z on the at least one organic ligand C,

groups X, Y and Z each being capable of acting as a crosslinking acceptor and as a crosslinking donator,

and optionally at least one solvent, selected from one or more members of the group consisting of aromatic, halogenated and aliphatic hydrocarbons solvents.

2. The optical medium according to claim 1 , wherein in the nanoparticle group X is capable of acting as a crosslinking acceptor with respect to group Y and as a crosslinking donator with respect to group Z, or as a crosslinking acceptor with respect to group Z and as a crosslinking donator with respect to group Y;

group Y is capable of acting as a crosslinking acceptor with respect to group Z and as a crosslinking donator with respect to group X, or as a crosslinking acceptor with respect to group X and as a crosslinking donator with respect to group Z; and

group Z is capable of acting as a crosslinking acceptor with respect to group X and as a crosslinking donator with respect to group Y, or as a crosslinking acceptor with respect to group Y and as a crosslinking donator with respect to group X.

3. The optical medium according to claim 1 , wherein the nanoparticle is produced by crosslinking the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C each represented by the general formula (I)

U—V—W   (I)

where U is at each occurrence in ligands A, B and C, identically or differently, a nanoparticle surface attaching group, V is at each occurrence in ligands A, B and C, identically or differently, a linker group, and W corresponds to crosslinkable functional groups X, Y and Z, respectively.

4. The optical medium according to claim 3 , wherein in the ligand in formula (I),

U is at each occurrence in ligands A, B and C, identically or differently, selected from the group consisting of a phosphonic acid group, a thiol group, a thiolate group, a thioic acid group, a dithioic acid group, a mercaptoester group, a carboxylic acid group, a carboxylate group, a phosphonate group, a thiocarbamate group, a phosphine group, a phosphinoxide group, an amine group, an amide group, and a selenol group;

V is at each occurrence in ligands A, B and C, identically or differently, selected from the group consisting of a straight-chain alkylene group having 1 to 20 C atoms, or branched alkylene group having 3 to 20 C atoms, where one or more non-adjacent methylene structural units (—CH 2 —) in said straight-chain and branched alkylene groups may in each case be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a sulfide group, a sulfoxide group, an ester group, a phosphoester group, an amide group or an imine group, or a straight-chain alkenylene group or alkynylene group having 2 to 20 C atoms or a branched alkenylene group or alkynylene group having 3 to 20 C atoms, where one or more methylene structural units (—CH 2 —) in said straight-chain and branched alkenylene or alkynylene groups may in each case be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a sulfide group, a sulfoxide group, an ester group, a phosphoester group, an amide group or an imine group; and

X, Y and Z are independently of each other selected from the group consisting of a thiol group, an acrylate group, a styrene group, a carbonate group, and a carbamate group.

5. The optical medium according to claim 4 , wherein in X, Y and Z the carbamate group is a urethane.

6. The optical medium according to claim 4 , wherein in the ligand U is in Zn-carboxylate, Zn-thiocarbamate, or Zn-phosphonate.

7. The optical medium according to claim 3 , wherein in the ligand group U is identical in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C and/or V is identical in each of the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C.

8. The optical medium according to claim 3 , wherein in the ligand U is a phosphonic acid group and wherein group V is a straight-chain alkylene group having 1 to 20 C atoms, where one or more non-adjacent methylene structural units (—CH 2 —) in said straight-chain alkylene group may be replaced by a phenylene group, a sulfonyl group, a carbonyl group, an ether group, a sulfide group, a sulfoxide group, an ester group, a phosphoester group, an amide group or an imine group.

9. The optical medium according to claim 1 , wherein in the ligand groups X, Y and Z are identical.

10. The optical medium according to claim 1 , wherein in the nanoparticle the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are identical.

11. The optical medium according to claim 1 , wherein in the ligand groups X, Y and Z are identically selected from the group consisting of a thiol group, an acrylate group, and a styrene group.

12. The optical medium according to claim 1 , wherein in the nanoparticle the at least one organic ligand A, the at least one organic ligand B and the at least one organic ligand C are identically selected from the group consisting of 11-mercaptoundecylphosphonic acid, 11-phosphonoundecyl acylate and p-[(4-ethenylphenyl)methyl] phosphonic acid.

13. The optical medium according to claim 1 , comprising at least one solvent, selected from one or more members of the group consisting of aromatic, halogenated and aliphatic hydrocarbons solvents.

14. Optical device comprising an optical medium according to claim 1 .