Charged organic thermally activated delayed fluorescence (TADF) species are described. A light-emitting electrochemical cell (LEEC) includes the charged organic thermally activated delayed fluorescence (TADF) species and sufficient counter ions to balance the charge on the charged organic thermally activated delayed fluorescence species, as emitter material. Also disclosed are OLEDSs containing the TADF species.

Provided are a core-shell structured perovskite nanocrystalline particle light-emitting body, a method of preparing the same, and a light emitting device using the same. The core-shell structured organic-inorganic hybrid perovskite nanocrystalline particle light-emitting body or metal halide perovskite nanocrystalline particle light-emitting body is able to be dispersed in an organic solvent, and has a perovskite nanocrystal structure and a core-shell structured nanocrystalline particle structure. Therefore, in the perovskite nanocrystalline particle light-emitting body of the present invention, as a shell is formed of a substance having a wider band gap than that of a core, excitons may be more dominantly confined in the core, and durability of the nanocrystal may be improved to prevent exposure of the core perovskite to the air using a perovskite or inorganic semiconductor, which is stable in the air, or an organic polymer.

Provided are an organic-inorganic hybrid perovskite nanocrystal particle light emitting body having a gradient structure, a method of producing the same, and a light emitting element using the same. The organic-inorganic hybrid perovskite nanocrystal particle light emitting body having a gradient structure includes an organic-inorganic hybrid perovskite nanocrystal which is dispersible in an organic solvent, wherein the nanocrystal has a gradient composition in which a composition is changed from the center thereof to the outside. Therefore, the gradual change in the content in the nanocrystal may be used to uniformly adjust a fraction in the nanocrystal, to reduce surface oxidation, and to improve exciton confinement in the perovskite present in large quantities inside the nanocrystal, and thus light emission efficiency may be improved and durability and stability may be increased.

The present disclosure discloses metal oxide nanoparticle ink, a method of preparing the same, a metal oxide nanoparticle thin film manufactured using the same, and a photoelectric device using the same. The method of preparing metal oxide nanoparticle ink according to an embodiment of the present disclosure includes a step of, using a ligand solution including a metal oxide and an organic ligand, synthesizing a first nanoparticle that is a metal oxide nanoparticle surrounded with the organic ligand; a step of preparing a dispersion solution by dispersing the first nanoparticle in a solvent; a step of preparing a second nanoparticle by mixing the dispersion solution and a pH-adjusted alcohol solvent and then performing ultrasonication treatment to remove the organic ligand surrounding the first nanoparticle; and a step of preparing metal oxide nanoparticle ink by dispersing the second nanoparticle in a dispersion solvent.

The present disclosure discloses metal oxide nanoparticle ink, a method of preparing the same, a metal oxide nanoparticle thin film manufactured using the same, and a photoelectric device using the same. The method of preparing metal oxide nanoparticle ink according to an embodiment of the present disclosure includes a step of, using a ligand solution including a metal oxide and an organic ligand, synthesizing a first nanoparticle that is a metal oxide nanoparticle surrounded with the organic ligand; a step of preparing a dispersion solution by dispersing the first nanoparticle in a solvent; a step of preparing a second nanoparticle by mixing the dispersion solution and a pH-adjusted alcohol solvent and then performing ultrasonication treatment to remove the organic ligand surrounding the first nanoparticle; and a step of preparing metal oxide nanoparticle ink by dispersing the second nanoparticle in a dispersion solvent.

Active emissive layers (e.g., of a light-emitting electrochemical cell (LEC)) are provided and can comprise zero-dimensional (0D) perovskite material in combination with a three-dimensional (3D) perovskite material, as well as electroluminescent devices (e.g., LECs) utilizing such active emissive layers and methods of fabricating and using such active emissive layers and electroluminescent devices. The 0D perovskite material can be incorporated into a matrix film of the 3D perovskite material. The 0D perovskite material can be, for example, perovskite nanocrystals (PNCs). The 0D perovskite material can be, for example, Cs.sub.4PbBr.sub.6, and the 3D perovskite material can be, for example, CsPbBr.sub.3.

Active emissive layers (e.g., of a light-emitting electrochemical cell (LEC)) are provided and can comprise zero-dimensional (0D) perovskite material in combination with a three-dimensional (3D) perovskite material, as well as electroluminescent devices (e.g., LECs) utilizing such active emissive layers and methods of fabricating and using such active emissive layers and electroluminescent devices. The 0D perovskite material can be incorporated into a matrix film of the 3D perovskite material. The 0D perovskite material can be, for example, perovskite nanocrystals (PNCs). The 0D perovskite material can be, for example, Cs.sub.4PbBr.sub.6, and the 3D perovskite material can be, for example, CsPbBr.sub.3.

Provided is an electrochemical luminescent cell 10 having a luminescent layer 12 and electrodes 13, 14 provided on each surface of the luminescent layer 12. The luminescent layer 12 comprises an organic polymeric luminescent material and a combination of at least two organic salts. In particular, the luminescent layer preferably comprises a combination of at least two types of ionic liquids represented by formula (1) (wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each represent an optionally-substituted alkyl group, alkoxy alkyl group, trialkylsilylalkyl group, alkenyl group, alkynyl group, aryl group or heterocylic group. R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different. M represents N or P. X.sup.− represents an anion.)

A method of fabricating a perovskite light emitting device is provided. In one embodiment, the method comprises the steps of: providing a substrate; providing a first electrode disposed over the substrate; providing a bank structure disposed over the substrate, wherein the bank structure is patterned so as to define at least one sub-pixel on the substrate; providing a first transport layer ink, wherein the first transport layer ink comprises at least one solvent and at least one first charge transport material mixed in the at least one solvent; depositing the first transport layer ink into the at least one sub-pixel over the first electrode using a method of inkjet printing; vacuum drying the first transport layer ink inside a vacuum drying chamber to assemble a first transport layer over the first electrode in the at least one sub-pixel; annealing the first transport layer; providing a perovskite ink, wherein the perovskite ink comprises at least one solvent and at least one perovskite light emitting material mixed in the at least one solvent; depositing the perovskite ink into the at least one sub-pixel over the first transport layer using a method of inkjet printing; vacuum drying the perovskite ink inside a vacuum drying chamber to assemble a perovskite emissive layer over the first transport layer in the at least one sub-pixel; annealing the perovskite emissive layer; and depositing a second electrode over the perovskite emissive layer using a method of vapour deposition. Perovskite light emitting devices and displays fabricated using the provided method are also provided.

The application provides an OLED device, a manufacturing method thereof, and a display device, which reduce or eliminate color cast in an image displayed by an existing OLED device due to different lifetimes of organic materials for light emitting layers emitting light of different colors in the OLED device. In the OLED device, a luminous efficiency regulator is disposed between a cathode and a light emitting layer of at least one sub-pixel, and a vibration characteristic peak of the luminous efficiency regulator falls within a wavelength range of light emitted from the corresponding light emitting layer, such that attenuation rates of lighting luminance of the light emitting layers emitting light of different colors are kept consistent with each other over time.