The purpose of the present invention is to provide a mechanoluminescent material which can be exhibit brighter luminescence compared to traditional SAO mechanoluminescent material even with respect to small strains and which has a relatively high mechanoluminescent capability even when left to stand for a long period of time after excitation. Provided is a strontium aluminate mechanoluminescent material containing Zr ions, characterized in that the Zr ions are contained in a reduced state, the content of the Zr ions is 10 mol % or less, and in a thermoluminescence measurement, one or more luminescence peaks are observed at a temperature of 100° C. or higher.

A metallic compound for use in an electronic apparatus having an organic light emitting element, the metallic compound having a refractive index: n.sub.620 nm≤about 1.60; n.sub.530 nm≤about 1.65; and n.sub.460nm≤about 1.68.

A light-emitting device is described that includes a plurality of partially drivable light sources, and a color conversion component configured to convert at least part of incident light from at least part of the light sources and emit outgoing light falling in a different wavelength region from the incident light, where the color conversion component includes a pyrromethene derivative.

An organic electroluminescent device having an anode, a cathode, and a light emitting layer between the anode and the cathode, in which the light emitting layer contains a first organic compound, a second organic compound, and a third organic compound that satisfy the following expression (A), the second organic compound is a delayed fluorescent material, and the third organic compound is a light emitting material, is capable of enhancing the light emission efficiency. E.sub.S1(A), E.sub.S1(B) and E.sub.S1 (C) represent a lowest singlet excitation energy level of the first, second and third organic compound, respectively.

E.sub.S1(A)>E.sub.S1(B)>E.sub.S1(C)(A)

An optical marking device including at least a first layer and a second layer disposed at least partially opposite each other, at least one of the first and second layers having an optically variable element being able to change colour between a first colour and a second colour, the first and second colours contrasting from a colour of the other layer in such a way that when the optically variable element displays the first colour, the first layer is visible and when the optically variable element displays the second colour, the second colour is visible, or when the optically variable element displays the first colour, the second layer is visible and when the optically variable element displays the second colour, the first layer is visible.

An organometallic compound represented by Formula I, an organic light-emitting device including the same, and a diagnostic composition including the organometallic compound.

##STR00001##

An organometallic compound represented by Formulae 1, 2, or 3 below: ##STR00001## wherein in Formulae 1, 2, and 3, groups and variables are the same as in the specification.

The present invention provides a planar electroluminescence (EL) device comprising a substrate layer, an electrode layer, a light emitting layer, and a modulating layer, wherein the electrode layer comprises a plurality of electrodes arranged on a same level over the substrate layer, and there is no contact between adjacent electrodes. In one embodiment, the device further comprises a hole injection layer (HIL), a hole transport layer (HTL), an electron injection layer (EIL) and an electrode transport layer (ETL). In one embodiment, the light emitting layer comprises organic light emitting polymers or organic light emitting molecules. The device of the present invention would emit light when liquid, polar component, or conductive solution is written directly on the light emitting layer. In one embodiment, the device can emit light for prolonged period when the light emitting layer is coated or deposited with conductive material.

Organic light emitting devices are described wherein the emissive layer comprises a host material containing an emissive molecule, which molecule is adapted to luminesce when a voltage is applied across the heterostructure, and the emissive molecule is selected from the group of phosphorescent organometallic complexes, including cyclometallated platinum, iridium and osmium complexes. The organic light emitting devices optionally contain an exciton blocking layer. Furthermore, improved electroluminescent efficiency in organic light emitting devices is obtained with an emitter layer comprising organometallic complexes of transition metals of formula L.sub.2MX, wherein L and X are distinct bidentate ligands. Compounds of this formula can be synthesized more facilely than in previous approaches and synthetic options allow insertion of fluorescent molecules into a phosphorescent complex, ligands to fine tune the color of emission, and ligands to trap carriers.

A color conversion sheet converts incident light into light with a wavelength longer than that of the incident light. The color conversion sheet includes the following layer (A) and layer (B): the layer (A): a layer containing an organic light-emitting material (a) that exhibits light emission with a peak wavelength observed in a region of 500 nm or more and 580 nm or less by using excitation light in a wavelength range of 400 nm or more and 500 nm or less and a binder resin; and the layer (B): a layer containing an organic light-emitting material (b) that exhibits light emission with a peak wavelength observed in a region of 580 nm or more and 750 nm or less by being excited by either or both of excitation light in a wavelength range of 400 nm or more and 500 nm or less and light emission from the organic light-emitting material (a) and a binder resin.