A quantum dot (QD) composite material includes at least three QD structural units arranged sequentially along a radial direction. Among the at least three QD structural units, each QD structural unit at a center of the QD composite material and each QD structural unit at a surface of the QD composite material have a gradient alloy composition structure with an energy level width increasing along the radial direction from the center to the surface, along the radial direction, energy levels of adjacent gradient alloy composition structures of the QD structure units are continuous. A QD structural unit located between the QD structural units at the center and the QD structural units at the surface have a homogeneous alloy composition structure.

The present disclosure provides a light-emitting layer, an organic light emitting diode (OLED) device, and a display apparatus. The light-emitting layer has a host material containing a first photocrosslinker group. A guest material containing a second photocrosslinker group is prepared. The host material and the guest material are mixed in a solvent to form a mixture. The mixture is coated, annealed, and UV-irradiated on a substrate to form the light-emitting layer. As such, the disclosed light-emitting layer is prepared by the polymerization after being on the substrate. The light-emitting layer has a mesh structure. The mesh structure improves energy transfer between the host material and guest material and increases the lifespan of the resultant OLED device and OLED display apparatus.

The present disclosure provides an aromatic heterocyclic compound having property of thermally activated delayed fluorescence (TADF). The aromatic heterocyclic compound has a structure represented by Formula (I), in which X.sub.1 and X.sub.2 each is S, O, Se, or C; D is an electron donor, A is an electron acceptor; m is a number of the electron donor D, and the m electron donors D are the same or different; n is a number of the electron acceptor, and the n electron acceptors are the same or different; and m and n are 1 or 2. The aromatic heterocyclic compound provides a high luminescence efficiency. Organic light-emitting display devices including such aromatic heterocyclic compound have improved luminescence efficiency, lower cost and longer service life by using the aromatic heterocyclic compound as a light-emitting material, a host material, or a guest material. ##STR00001##

Provided is a quantum dot light-emitting device and a display apparatus including the same. The quantum dot light-emitting device comprises: an anode; a cathode; a hole transport layer disposed between the anode and the cathode; a light-emitting layer disposed between the hole transport layer and the cathode, the light-emitting layer including a quantum dot having a core-shell structure; and a buffer layer disposed between the hole transport layer and the light-emitting layer, wherein the buffer layer contains an organic compound or derivatives thereof. The external quantum efficiency and device stability are improved. an aromatic hydrocarbon compound or derivatives thereof having a functional group selected from the group consisting of a hydroxyl group (—OH), a carboxyl group (—COOH), an amino group (—NR, —NH, —NH.sub.2, where R is a C1 to C6 monovalent hydrocarbon group or derivatives thereof) and a thiol group (—SH).

A QD particle dispersion contains a surface modification compound that protects a surface of QD phosphor particles dispersed in a solvent. The surface modification compound includes a heteroatom-containing functional group and a chain-type saturated hydrocarbon group. The QD particle dispersion is configured such that the absolute value of a difference between the surface free energy of an underlayer that provides a foundation for forming a QD layer in the light-emitting element and the surface free energy of the QD layer is 5 mN/m or less.

The present disclosure provides a quantum dot (QD) light emitting diode including: a first electrode; a second electrode facing the first electrode; a QD emitting material layer positioned between the first electrode and the second electrode and including a QD and an organic material; a hole auxiliary layer positioned between the first electrode and the QD emitting material layer; and an electron auxiliary layer positioned between the QD emitting material layer and the second electrode, wherein the organic material has a highest occupied molecular orbital (HOMO) level higher than a material of the hole auxiliary layer.

Disclosed is an optoelectronic device including a first electrode and a second electrode facing each other, a hole transport layer and an light emitting layer disposed between the first electrode and the second electrode, wherein the hole transport layer includes a compound represented by Chemical Formula 1 or a polymer thereof and the light emitting layer includes a perovskite compound. ##STR00001##
Definitions of Chemical Formula 1 are the same as described in the detailed description.

A light-emitting element includes a first electrode, a second electrode disposed on the first electrode, and at least one functional layer disposed between the first electrode and the second electrode. The at least one functional layer includes a charge transport material derived from an azide compound represented by Formula 1 and a polymer compound including an aromatic ring group. The light-emitting element may be formed by a wet process and may exhibit improved flexibility.

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A quantum-dot (QD) light-emitting diode (QLED) device has a multiple-layer active emission region. The multiple-layer active emission region has n QD layers interleaved with (n−1) quantum-barrier (QB) layers where n is a positive integer greater than one, such that each QB layer is sandwiched between two adjacent QD layers.

A quantum dot (QD) composite material includes at least three QD structural units arranged sequentially along a radial direction. Among the at least three QD structural units, each QD structural unit at a center of the QD composite material and each QD structural unit at a surface of the QD composite material have a gradient alloy composition structure with an energy level width increasing along the radial direction from the center to the surface, along the radial direction, energy levels of adjacent gradient alloy composition structures of the QD structure units are continuous. A QD structural unit located between the QD structural units at the center and the QD structural units at the surface have a homogeneous alloy composition structure.