An organic electroluminescent device includes an organic functional layer which is provided between a light emitting layer and an electron transport region, and has a refractive index equal to or greater than the refractive index of the corresponding light emitting layer. The organic electroluminescent device simultaneously exhibits high luminous efficiency, low driving voltage, long service life, and the like.

A display device, an electronic device, or a lighting device that is unlikely to be broken is provided. A flexible first substrate and a flexible second substrate overlap with each other with a display element provided therebetween. A flexible third substrate is bonded on the outer surface of the first substrate, and a flexible fourth substrate is bonded on the outer surface of the second substrate. The third substrate is formed using a material softer than the first substrate, and the fourth substrate is formed using a material softer than the second substrate.

An organic light-emitting device including a first electrode, a second electrode facing the first electrode, and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer includes an emission layer, wherein the emission layer includes a host and a dopant, and wherein the organic light-emitting device satisfies predetermined conditions described in the specification.

An organic electroluminescence device, a preparation method thereof, and a display apparatus, the organic electroluminescence device including an organic light emitting layer which includes a host material, a sensitizer material, and a resonance thermally activated delayed fluorescent material, where the host material is a wide bandgap material, and the sensitizer material is a thermally activated delayed fluorescent material. The singlet state energy level of the thermally activated delayed fluorescent material falls between the singlet state energy level of the wide bandgap material and the singlet state energy level of the resonance thermally activated delayed fluorescent material. The triplet state energy level of the thermally activated delayed fluorescent material falls between the triplet state energy level of the wide bandgap material and the triplet state energy level of the resonance thermally activated delayed fluorescent material.

Provided are an organic electroluminescent material and a device thereof. The organic electroluminescent material includes a metal M and at least one C{circumflex over ( )}N bidentate ligand L.sub.a coordinated with the metal M, the maximum emission wavelength of the photoluminescence spectrum of the organic electroluminescent material at room temperature is greater than or equal to 410 nm and less than or equal to 700 nm, and the emission spectrum area ratio of the organic electroluminescent material is less than or equal to 0.145. The metal complex has significant advantages in organic electroluminescent devices, in particular the improvement of device efficiency. Further provided are an organic electroluminescent device including the metal complex and a compound composition including the metal complex.

A foldable display device includes an organic light emitting diode (OLED) display substrate, a stress relief layer parallel with the OLED display substrate, and a first adhesive layer between the OLED display substrate and the stress relief layer. A value of v/E of the OLED display substrate is larger than a value of v/E of the stress relief layer, where v is a Poisson's ratio and E is a Young's modulus.

A formulation for preparing organic electronic devices, has: a p-type organic semiconductor polymer including a conjugated aryl compound, a conjugated heteroaryl compound, or a mixture of at least two of these compounds; an n-type semiconductor material having fullerene, substituted fullerene, or a mixture of at least two of these compounds; and a non-aqueous solvent. The concentration of the p-type organic semiconductor polymer is in the range from 12 mg/mL to 17 mg/mL per milliliter of solvent and the concentration of the p-type organic semiconductor material is in the range from 24 mg/mL to 28 mg/mL per milliliter of solvent.

An alkali-free glass of the present invention includes as a glass composition, in terms of mass %, 55% to 70% of SiO.sub.2, 15% to 25% of Al.sub.2O.sub.3, 0% to 5% of B.sub.2O.sub.3, 3% to 10% of MgO, 7% to 20% of SrO, and 0% to 5% of BaO, is substantially free of an alkali metal oxide, and has a strain point of more than 720° C.

A display substrate includes a base and blue light-emitting units disposed on the base. A blue light-emitting unit includes a first electrode, a first light-emitting layer and a second electrode that are sequentially disposed on the base. Of the first electrode and the second electrode, one electrode is configured to reflect light, and another electrode is configured to transmit light. The first light-emitting layer is configured to emit light having a spectrum whose full width at half maximum is less than or equal to 16 nm.

The disclosure provides a local stretch packaging structure, including a substrate, a flexible electronic element, a plurality of light-emitting display elements, and a packaging layer. The flexible electronic element is disposed on the substrate. These light-emitting display elements are disposed on the flexible electronic element. The packaging layer includes a packaging area and a non-packaging area. The packaging area covers the upper surface and sidewalls of these light-emitting display elements. The non-packaging area is directly covered the flexible electronic element that is not disposed with these light-emitting display elements.