Quantum-dot light-emitting diode and method for producing quantum-dot light-emitting diode

1. A quantum dot light emitting diode (QLED) having an invert structure comprising:

a cathode including a transparent electrode;

an electron transport layer positioned on the cathode;

a quantum dot layer positioned on the electron transport layer;

a hole transport layer positioned on the quantum dot layer; and

an anode positioned on the hole transport layer,

wherein the quantum dot layer includes,

a surface-passivated quantum dot,

the surface-passivated quantum dot including:

a perovskite quantum dot (PeQD) including a compound having a perovskite structure represented by the following Chemical Formula 1; and

a surface treatment layer positioned on a surface of the quantum dot and including an organic ligand represented by the following Chemical Formula 2 and an organic ligand represented by the following Chemical Formula 3,

ABX 1 3   [Chemical Formula 1]

in Chemical Formula 1,

A is one of CH 3 NH 2 , NH 2 CH═NH 1 —*, Cs, Rb, Ba, In, K, and Tl,

B is one element of Pb, Sn, Bi, Ag, Ge, and Zr,

X 1 is one element of F, Cl, Br, and I, and

a moiety indicated by * in NH 2 CH═NH 1 —* is bound to B,

in Chemical Formula 2,

R 1 is a substituted or unsubstituted (C6-C20) aryl group or substituted or unsubstituted (C1-C6) alkyl group, and

moieties indicated by * are each bound to the surface of the quantum dot,

in Chemical Formula 3,

L is one of (C1-C5) alkylene groups,

R 2 to R 4 are each one of hydrogen, deuterium, tritium, a substituted or unsubstituted (C1-C6) alkyl group, and a substituted or unsubstituted (C6-C20) aryl group, and

n is 0 or 1.

2. The quantum dot light emitting diode of claim 1 , wherein:

the quantum dot layer,

has a total thickness of 1 to 300 nm.

3. The quantum dot light emitting diode of claim 2 , wherein:

the quantum dot layer,

includes a thin film of 1 to 10 layers.

4. The quantum dot light emitting diode of claim 3 , wherein:

the thin film of one layer,

has a thickness of 1 to 30 nm.

5. The quantum dot light emitting diode of claim 1 , wherein:

the surface-passivated quantum dot,

is uniformly distributed in a front surface of the quantum dot layer.

6. The quantum dot light emitting diode of claim 5 , wherein:

the surface-passivated quantum dot,

is distributed in a ratio of 80 sq % or more based on 100 sq % of the front surface of the quantum dot layer.

7. The quantum dot light emitting diode of claim 6 , wherein:

in the quantum dot layer,

the surface-passivated quantum dot is distributed in a ratio of 80 to 100 vol % based on a total volume (100 vol %) of the quantum dot layer.

8. The quantum dot light emitting diode of claim 1 , wherein:

the electron transport layer,

is a thin film containing at least one of metal oxide, bathocuproine (BCP), bathophenanthroline (Bphene), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), tris(8-hydroxyquinolinato)aluminum (Alq3), 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene (TPBi), and 1,3,5-triazine (T2T).

9. The quantum dot light emitting diode of claim 1 , wherein:

the hole transport layer,

is a thin film containing at least one of N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4″-diamine (a-NPD), N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4″-diamine (NPB), 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN), PEDOT:PSS, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), amorphous 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (mCBP), 2,2′,7,7′-tetrakis [N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD), and poly(9-vinylcarbazole) (PVK).

10. The quantum dot light emitting diode of claim 1 , wherein:

the passivation layer

is formed by a solid-state ligand exchange (SLE) reaction.

11. The quantum dot light emitting diode of claim 10 , wherein:

the solid-state ligand exchange reaction

is carried out on the electron transport layer.

12. The quantum dot light emitting diode of claim 1 , further comprising

a polymer electrolyte layer positioned between the electron transport layer and the quantum dot layer.

13. The quantum dot light emitting diode of claim 10 , further comprising:

a polymer electrolyte layer positioned between the electron transport layer and the quantum dot layer, and

the solid-state ligand exchange reaction is carried out on the polymer electrolyte layer.

14. The quantum dot light emitting diode of claim 12 , wherein:

the polymer electrolyte layer,

is made of one or two or more polymer electrolytes of poly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN), polyethylene imine (PEI), polyethyleneimine ethoxylated (PEIE).

15. The quantum dot light emitting diode of claim 1 , wherein:

the cathode,

includes a transparent electrode made of ITO, FTO, an Ag nano-wire, a Cu nano-wire, or a combination thereof.

16. The quantum dot light emitting diode of claim 1 , wherein:

the anode,

is made of Al, Ag, Au, or a combination thereof.

17. A method of manufacturing a quantum dot light emitting diode (QLED) having an invert structure, the method comprising:

preparing a cathode including a transparent electrode;

forming an electron transport layer on the cathode;

forming a quantum dot layer on the electron transport layer;

forming a hole transport layer on the quantum dot layer; and

forming an anode on the hole transport layer,

wherein the forming of the quantum dot layer on the electron transport layer includes: manufacturing a surface-passivated quantum dot; and applying and coating a solution containing the surface-passivated quantum dot on the electron transport layer,

the manufacturing of the surface-passivated quantum dot including: mixing a ligand exchange solution containing an organic ligand represented by R 1 —COOH, an organic ligand represented by the following Chemical Formula 3, and a second organic solvent with a pretreated quantum dot to induce a ligand exchange reaction on a surface of the quantum dot,

in the pretreating of the surface of the quantum dot, a pretreatment layer containing a fatty acid based organic ligand and a fatty amine based organic ligand is formed on the surface of the quantum dot, and

in the inducing of the ligand exchange reaction on the surface of the quantum dot, the pretreatment layer is removed from the surface of the quantum dot, and at the same time, a final passivation layer containing an organic ligand represented by the following Chemical Formula 2 and the organic ligand represented by the following Chemical Formula 3 is formed:

ABX 1 3   [Chemical Formula 1]

in Chemical Formula 1,

A is one of CH 3 NH 2 , NH 2 CH═NH 1 —*, Cs, Rb, Ba, In, K, and Tl,

B is one element of Pb, Sn, Bi, Ag, Ge, and Zr,

X 1 is one element of F, Cl, Br, and I, and

a moiety indicated by * in NH 2 CH═NH 1 —* is bound to B,

in Chemical Formula 2,

R 1 is a substituted or unsubstituted (C6-C20) aryl group or substituted or unsubstituted (C1-C6) alkyl group, and

moieties indicated by * are each bound to the surface of the quantum dot,

in Chemical Formula 3,

L is one of (C1-C5) alkylene groups,

R 2 to R 4 are each one of hydrogen, deuterium, tritium, a substituted or unsubstituted (C1-C6) alkyl group, and a substituted or unsubstituted (C6-C20) aryl group, and

n is 0 or 1.

18. A method of manufacturing a quantum dot light emitting diode (QLED) having an invert structure, the method comprising:

preparing a cathode including a transparent electrode;

forming an electron transport layer on the cathode;

forming a polymer electrolyte layer on the electron transport layer;

forming a quantum dot layer on the polymer electrolyte layer;

forming a hole transport layer on the quantum dot layer; and

forming an anode on the hole transport layer,

wherein the forming of the quantum dot layer on the polymer electrolyte layer includes: manufacturing a surface-passivated quantum dot; and applying and coating a solution containing the surface-passivated quantum dot on the polymer electrolyte layer,

the manufacturing of the surface-passivated quantum dot including: mixing a ligand exchange solution containing an organic ligand represented by R 1 —COOH, an organic ligand represented by the following Chemical Formula 3, and a second organic solvent with a pretreated quantum dot to induce a ligand exchange reaction on a surface of the quantum dot,

in the pretreating of the surface of the quantum dot, a pretreatment layer containing a fatty acid based organic ligand and a fatty amine based organic ligand is formed on the surface of the quantum dot, and

in the inducing of the ligand exchange reaction on the surface of the quantum dot, the pretreatment layer is removed from the surface of the quantum dot, and at the same time, a final passivation layer containing an organic ligand represented by the following Chemical Formula 2 and the organic ligand represented by the following Chemical Formula 3 is formed:

ABX 1 3   [Chemical Formula 1]

in Chemical Formula 1,

A is one of CH 3 NH 2 , NH 2 CH═NH 1 —*, Cs, Rb, Ba, In, K, and Tl,

B is one element of Pb, Sn, Bi, Ag, Ge, and Zr,

X 1 is one element of F, Cl, Br, and I, and

a moiety indicated by * in NH 2 CH═NH 1 —* is bound to B,

in Chemical Formula 2,

R 1 is a substituted or unsubstituted (C6-C20) aryl group or substituted or unsubstituted (C1-C6) alkyl group, and

moieties indicated by * are each bound to the surface of the quantum dot,

in Chemical Formula 3,

L is one of (C1-C5) alkylene groups,

R 2 to R 4 are each one of hydrogen, deuterium, tritium, a substituted or unsubstituted (C1-C6) alkyl group, and a substituted or unsubstituted (C6-C20) aryl group, and

n is 0 or 1.

19. A method of manufacturing a quantum dot light emitting diode, the method comprising:

preparing a cathode including a transparent electrode;

forming an electron transport layer on the cathode;

forming a quantum dot layer on the electron transport layer;

forming a hole transport layer on the quantum dot layer; and

forming an anode on the hole transport layer,

wherein the forming of the quantum dot layer on the electron transport layer includes:

mixing a pretreatment solution containing a fatty acid based organic ligand, a fatty amine based organic ligand, and a first organic solvent with a perovskite quantum dot (PeQD) containing a compound having a perovskite structure represented by the following Chemical Formula 1 to pretreat a surface of the quantum dot;

coating the pretreated quantum dot on the electron transport layer; and

applying a ligand exchange solution containing an organic ligand represented by R 1 —COOH, an organic ligand represented by the following Chemical Formula 3, and a second organic solvent on the electron transport layer to induce a ligand exchange reaction on the surface of the quantum dot coated on the electron transport layer,

in the pretreating of the surface of the quantum dot, a pretreatment layer containing a fatty acid based organic ligand and a fatty amine based organic ligand is formed on the surface of the quantum dot, and

in the inducing of the ligand exchange reaction on the surface of the quantum dot coated on the electron transport layer, the pretreatment layer is removed from the surface of the quantum dot coated on the electron transport layer, and at the same time, a final passivation layer containing an organic ligand represented by the following Chemical Formula 2 and the organic ligand represented by the following Chemical Formula 3 is formed:

ABX 1 3   [Chemical Formula 1]

in Chemical Formula 1,

A is one of CH 3 NH 2 , NH 2 CH═NH 1 —*, Cs, Rb, Ba, In, K, and Tl,

B is one element of Pb, Sn, Bi, Ag, Ge, and Zr,

X 1 is one element of F, Cl, Br, and I, and

a moiety indicated by * in NH 2 CH═NH 1 —* is bound to B,

in Chemical Formula 2,

R 1 is a substituted or unsubstituted (C6-C20) aryl group or substituted or unsubstituted (C1-C6) alkyl group, and

moieties indicated by * are each bound to the surface of the quantum dot,

in Chemical Formula 3,

L is one of (C1-C5) alkylene groups,

R 2 to R 4 are each one of hydrogen, deuterium, tritium, a substituted or unsubstituted (C1-C6) alkyl group, and a substituted or unsubstituted (C6-C20) aryl group, and

n is 0 or 1.