An organic electroluminescent device having high efficiency and high driving stability, and a material suitable for the organic electroluminescent device are provided. The material for organic electroluminescent devices comprises an indolocarbazole compound represented by a general formula (1). In the formula, the ring a is represented by a formula (1a), X is NR, S, O or CR.sub.2, and Ar.sup.1 and Ar.sup.2 are an aromatic heterocyclic group represented by a formula (1b). Y is N or CR, and at least one is N. L.sup.1 is an aromatic hydrocarbon group. The material for the organic electroluminescent devices is suitable as material for the host of the light emitting layer or the hole blocking layer of organic EL devices.

##STR00001##

Disclosed are a series of photoisomeric compounds, preparation method therefor and device comprising the compounds, wherein a photoisomeric compound-graphene molecular junction device is formed by linking the photoisomeric compound to a gap of two-dimensional monolayer graphene having a nano-gap array via an amide covalent bond. When a single photoisomeric compound is bridged to the gap of the two-dimensional monolayer graphene having a nano-gap array, the devices have a reversible light-controlled switching function and a reversible electrically-controlled switching function. A molecular switch device prepared by the method can achieve a high reversibility and a good reproducibility. The number of light-controlled switching cycles can exceed 10.sup.4, and the number of electrically-controlled switching cycles can reach about 10.sup.5 or greater. Moreover, the above-mentioned reversible molecular switch device remains stable within a period of more than one year. In addition, flexible non-losable organic memory transistor devices and light-responsive organic transistor devices can be constructed using the above-mentioned series of photoisomeric compounds.

An electroluminescent device, a display substrate, and a display apparatus. The electroluminescent device comprises: an electron transport layer (1) and a quantum dot light emitting layer (3) that are arranged in a stack mode; and an ionic complex layer (2) located between the electron transport layer (1) and the quantum dot light emitting layer (3), wherein a built-in electric field is formed in the ionic complex layer (2).

An organic light-emitting device including a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer includes an emission layer, the emission layer includes a host, a dopant, and a sensitizer, the host does not include a metal atom, the dopant emits light, and the light has a decay time of about 100 nanoseconds or less, and the sensitizer includes an organometallic compound represented by one selected from Formulae 1 and 2 described in the specification.

A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.

A tertiary amine compound is provided. The tertiary amine compound is represented by the following general formula (1):

##STR00001##

where each of Ar.sub.1 and Ar.sub.2 independently represents a benzene ring having an alkyl group or an alkoxy group, an unsubstituted benzene ring, a naphthalene ring having an alkyl group or an alkoxy group, or an unsubstituted naphthalene ring.

A compound represented by Chemical Formula 1, an organic optoelectronic device including the same, and a display device including the organic optoelectronic device are provided. The structure of the compound represented by Chemical Formula 1 is described in the present specification.

A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.

A photoelectric conversion element comprising; a conductive layer, a porous semiconductor layer disposed on the conductive layer, a counter electrode facing the porous semiconductor layer, a dye included in the porous semiconductor layer, a electrolyte filling a space between the porous semiconductor and the counter electrode, I-/I3-based redox species and an additive included in the electrolyte, wherein the additive is at least one selected from group consisting of pyrazole and pyrazole derivative, which have two lone pairs of nitrogen atoms in pyrazol ring when the additives dissolved in the electrolyte.

A dye-sensitized solar cell including a working electrode having a photocatalytic film, a counter electrode, and an electrolyte-containing layer or solid charge-transfer layer containing a basic compound, wherein the photocatalytic film includes an oxide semiconductor layer containing a dye compound represented by the following formula (1), ##STR00001## wherein Y is an optionally substituted hydrocarbon group having 1 to 20 carbon atoms and having —CO—NR.sup.4— or —SO.sub.2—NR.sup.4— in the group, or a direct bond, Z is a conjugated group, R.sup.1, R.sup.2, and R.sup.3 each represent an optionally substituted hydrocarbon group or an optionally substituted hydrocarbonoxy group, at least one of R.sup.1, R.sup.2, and R.sup.3 is an optionally substituted hydrocarbonoxy group, and R.sup.4 represents a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms.