Perovskite light emitting device containing exciton buffer layer and method for manufacturing same

1. A light emitting device comprising:

a first electrode;

an exciton buffer layer disposed on the first electrode and comprising a conductive material and a fluorine-based material having lower surface energy than the conductive material;

a light emitting layer disposed on the exciton buffer layer and comprising a perovskite material; and

a second electrode disposed on the light emitting layer.

2. The light emitting device of claim 1 , wherein the exciton buffer layer is configured so that a conductive layer comprising the conductive material and a surface buffer layer comprising the fluorine-based material having lower surface energy than the conductive material are sequentially deposited.

3. The light emitting device of claim 2 , wherein the surface buffer layer has a thickness of 3 nm or more.

4. The light emitting device of claim 1 , wherein the exciton buffer layer has a conductivity of 10 −7 S/cm to 1,000 S/cm.

5. The light emitting device of claim 1 , wherein the fluorine-based material has a surface energy of 30 mN/m or less.

6. The light emitting device of claim 1 , wherein a concentration of the fluorine-based material in a second surface of the surface buffer layer opposite to a first surface, which is closer to the conductive layer, is higher than a concentration of the fluorine-based material in the first surface of the surface buffer layer.

7. The light emitting device of claim 6 , wherein a work function determined for the second surface of the conductive layer is greater than or equal to 5.0 eV.

8. The light emitting device of claim 1 , wherein the fluorine-based material is an ionomer comprising at least one F element.

9. The light emitting device of claim 8 , wherein the ionomer is a fluorinated ionomer.

10. The light emitting device of claim 1 , wherein the fluorine-based material comprises at least one ionomer selected from the group consisting of ionomers having structures represented by the following Formulas 1 to 12:

wherein m is a number ranging from 1 to 10,000,000, x and y are each independently a number ranging from 0 to 10, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m is a number ranging from 1 to 10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are each independently a number ranging from 0 to 20, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are each independently a number ranging from 0 to 20, M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, z is a number ranging from 0 to 20, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are each independently a number ranging from 0 to 20, Y represents one selected from —COO − M + , —SO 3 − NHSO 2 CF 3 + , and —PO 3 2− (M + ) 2 , and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , and RCHO + (R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 ) n NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n −, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000;

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x is a number ranging from 0 to 20, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, x and y are each independently a number ranging from 0 to 20, and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50);

wherein m and n are 0<m≤10,000,000 and 0≤n<10,000,000, R f ═—(CF 2 ) z — (where z is an integer ranging from 1 to 50, provided that 2 is excluded), —(CF 2 CF 2 O) z CF 2 CF 2 — (where z is an integer ranging from 1 to 50), —(CF 2 CF 2 CF 2 O) z CF 2 CF 2 — (where z is an integer ranging from 1 to 50), and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 ) n NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50); and

wherein m and n are 0≤m<10,000,000 and 0<n≤10,000,000, x and y are each independently a number ranging from 0 to 20, Y represents one selected from —SO 3 − M + , —COO − M + , —SO 3 − NHSO 2 CF 3 + , and —PO 3 2− (M + ) 2 , and M + represents Na + , K + , Li + , H + , CH 3 (CH 2 )—NH 3 + (where n is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , or RCHO + (where R represents CH 3 (CH 2 ) n —, where n is an integer ranging from 0 to 50).

11. The light emitting device of claim 1 , wherein the fluorine-based material comprises at least one ionomer or fluorinated oligomer selected from the group consisting of ionomers or fluorinated oligomers having structures represented by the following Formulas 13 to 19:

wherein R 11 to R 14 , R 21 to R 28 , R 31 to R 38 , R 41 to R 48 , R 51 to R 58 , and R 61 to R 68 are each independently selected from hydrogen, —F, a C 1 -C 20 alkyl group, a C 1 -C 20 alkoxy group, a C 1 -C 20 alkyl group substituted with one or more —F radicals, a C 1 -C 20 alkoxy group substituted with one or more —F radicals, Q 1 , —O—(CF 2 CF(CF 3 )—O) n —(CF 2 ) m -Q 2 (where n and m are each independently an integer ranging from 0 to 20, provided that the sum of n and m is greater than or equal to 1), and —(OCF 2 CF 2 ) x -Q 3 (where x is an integer ranging from 1 to 20), where Q 1 to Q 3 represent an ion group, where the ion group comprises an anionic group and a cationic group, the anionic group is selected from PO 3 2− , SO 3 − , COO − , CH 3 COO − , and BO 2 2− , the cationic group comprises one or more of a metal ion and organic ion, the metal ion is selected from Na + , K + , Li + , M +2 , Zn +2 , and Al +3 , and the organic ion is selected from H + , CH 3 (CH 2 ) n1 NH 3 + (where n1 is an integer ranging from 0 to 50), NH 4 + , NH 2 + , NHSO 2 CF 3 + , CHO + , C 2 H 5 OH + , CH 3 OH + , and RCHO + (where R represents CH 3 (CH 2 ) n2 —, and n2 is an integer ranging from 0 to 50);

wherein at least one of R 11 to R 14 , at least one of R 21 to R 28 , at least one of R 31 to R 38 , at least one of R 41 to R 48 , at least one of R 51 to R 58 , and at least one of R 61 to R 68 are selected from —F, a C 1 -C 20 alkyl group substituted with one or more —F radicals, a C 1 -C 20 alkoxy group substituted with one or more —F radicals, —O—(CF 2 CF(CF 3 )—O) n —(CF 2 ) m -Q 2 , and —(OCF 2 CF 2 ) X -Q 3 ; and

X-M f n -M h m -M a r -G  <Formula 19>

wherein X represents an end group;

M f represents a unit derived from a fluorinated monomer obtained by condensation reaction of perfluoropolyether alcohol, polyisocyanate, and an isocyanate-reactive non-fluorinated monomer;

M h represents a unit derived from a non-fluorinated monomer;

M a represents a unit having a silyl group represented by —Si(Y 4 )(Y 5 )(Y 6 ), where Y 4 , Y 5 and Y 6 each independently represent a substituted or unsubstituted C 1 -C 20 alkyl group, a substituted or unsubstituted C 6 -C 30 aryl group, or a hydrolysable substituent, provided that at least one of Y 4 , Y 5 and Y 6 is the hydrolysable substituent;

G is a monovalent organic group including a residue of a chain transfer agent;

n is a number ranging from 1 to 100;

m is a number ranging from 0 to 100; and

r is a number ranging from 0 to 100;

provided that the sum of n, m and r is at least 2.

12. The light emitting device of claim 1 , wherein the conductive material comprises at least one selected from the group consisting of a conductive polymer, a metallic carbon nanotube, graphene, a reduced graphene oxide, metal nanowires, semiconductor nanowires, carbon nanodots, metal nanodots, and a conductive oxide.

13. The light emitting device of claim 12 , wherein the conductive polymer comprises at least one selected from the group consisting of polythiophene, polyaniline, polypyrrole, polystyrene, sulfonated polystyrene, poly(3,4-ethylene dioxythiopene), a self-doped conductive polymer, and a derivative thereof.

14. The light emitting device of claim 12 , wherein at least one moiety represented by one selected from S(Z 100 ) and —Si(Z 101 )(Z 102 )(Z 103 ) (where Z 100 , Z 101 , Z 102 , and Z 103 are each independently hydrogen, a halogen atom, a substituted or unsubstituted C 1 -C 20 alkyl group, or a substituted or unsubstituted C 1 -C 20 alkoxy group) is bound to the metal nanowires, the semiconductor nanowires, the carbon nanodots, or the metal nanodots.

15. The light emitting device of claim 12 , wherein the conductive oxide comprises at least one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), SnO 2 , and InO 2 .

16. The light emitting device of claim 1 , wherein the exciton buffer layer further comprises at least one additive selected from the group consisting of a carbon nanotube, graphene, a reduced graphene oxide, metal nanowires, metal carbon nanodots, semiconductor quantum dots, semiconductor nanowires, and metal nanodots.

17. The light emitting device of claim 1 , wherein the exciton buffer layer further comprises a crosslinking agent.

18. The light emitting device of claim 17 , wherein the crosslinking agent comprises at least one functional group selected from the group consisting of an amine group (—NH 2 ), a thiol group (—SH), and a carboxyl group (—COO—).

19. The light emitting device of claim 17 , wherein the crosslinking agent comprises at least one selected from the group consisting of a bis(phenyl azide)-based material, a diaminoalkane-based material, a dithiol-based material, a dicarboxylate, an ethylene glycol di(meth)acrylate derivative, a methylenebisacrylamide derivative, and divinylbenzene (DVB).

20. The light emitting device of claim 1 , wherein the perovskite is in the form of particles or thin films having a nanocrystalline structure.

21. The light emitting device of claim 20 , further comprising a plurality of alkyl halides surrounding the perovskite nanocrystals.

22. The light emitting device of claim 1 , wherein the perovskite has a structure of A 2 BX 4 , ABX 4 , ABX 3 or A n−1 B n X 3n+1 (where n is an integer ranging from 2 to 6),

wherein A is an organic ammonium material, B is a metal material, and X is a halogen element.

23. The light emitting device of claim 22 , wherein A is (CH 3 NH 3 ) n , (C m H 2m+1 ) x NH 4−x , ((C m H 2m+1 ) y NH 3 )(CH 2 ) z NH 3 , (CF 3 NH 3 ), (C m H 2m+1 ) x NH 4−x , ((C m H 2m+1 ) y NH 3−y )(CH 2 ) z NH 3 , (CH(NH 2 ) 2 ), (C m H 2m+1 )(C(NH 2 ) 2 ), (C m H 2m+1 )(C(NH 2 ) 2 ), or a combination thereof (where n, m, x, y, and z are an integer greater than or equal to 1),

B is a divalent transition metal, a molecule, a rare earth metal, an alkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or a combination thereof, and

X is Cl, Br, I, or a combination thereof.

24. A method for manufacturing a light emitting device, comprising:

forming a first electrode;

forming an exciton buffer layer, which comprises a conductive material and a fluorine-based material having lower surface energy than the conductive material, on the first electrode;

forming a light emitting layer, which comprises a perovskite material comprising perovskite nanocrystals, on the exciton buffer layer; and

forming a second electrode on the light emitting layer.

25. The method of claim 24 , wherein the forming of the exciton buffer layer comprises:

mixing the conductive material and the fluorine-based material in a solvent to prepare a mixed solution;

coating the first electrode with the mixed solution; and

thermally treating the coated thin film so that a conductive layer comprising the conductive material and a surface buffer layer comprising the fluorine-based material are sequentially formed through self-assembly.

26. The method of claim 24 , wherein the perovskite has a structure of A 2 BX 4 , ABX 4 , ABX 3 or A n−1 B n X 3n+1 (where n is an integer ranging from 2 to 6),

wherein A is an organic ammonium material, B is a metal material, and X is a halogen element.

27. The method of claim 24 , wherein A is (CH 3 NH 3 ) n , (C m H 2m+1 ) x NH 4−x , ((C m H 2m+1 ) y NH 3−y )(CH 2 ) z NH 3 , (C m H 2m+1 ) x NH 4−x , ((C m H 2m+1 ) y NH 3−y )(CH 2 ) z NH 3 , (CH(NH 2 ) 2 ), (C m H 2m+1 )(C(NH 2 ) 2 ), Cs, (C m H 2m+1 )(C(NH 2 ) 2 ), or a combination thereof (where n, m, x, y, and z are integer greater than or equal to 1),

B is a divalent transition metal, molecule, a rare earth metal, an alkaline earth metal, Pb, Sn, Ge, Ga, In, Al, Sb, Bi, Po, or a combination thereof, and

X is Cl, Br, I, or a combination thereof.

28. A light emitting device comprising:

a first electrode;

an exciton buffer layer disposed on the first electrode and comprising a conductive material and a fluorine-based material having lower surface energy than the conductive material;

a light emitting layer disposed on the exciton buffer layer and comprising an inorganic metal halide perovskite material; and

a second electrode disposed on the light emitting layer.

29. The light emitting device of claim 28 , wherein the exciton buffer layer is configured so that a conductive layer comprising the conductive material and a surface buffer layer comprising the fluorine-based material having lower surface energy than the conductive layer are sequentially deposited.

30. The light emitting device of claim 29 , wherein the surface buffer layer has a thickness of 3 nm or more.

31. The light emitting device of claim 28 , wherein the exciton buffer layer has a conductivity of 10 −7 S/cm to 1,000 S/cm.

32. The light emitting device of claim 28 , wherein the fluorine-based material has a surface energy of 30 mN/m or less.

33. A solar cell comprising:

a first electrode;

an exciton buffer layer disposed on the first electrode and comprising a conductive material and a fluorine-based material having lower surface energy than the conductive material;

a photoactive layer disposed on the exciton buffer layer and comprising a perovskite material; and

a second electrode disposed on the photoactive layer.