A database system uses byte ordering for keys and a trie index to reference stored data. The keys of a database are converted into byte-comparable sequences of byte values. The trie index is generated including nodes connected by edges defining paths from a root node to leaf nodes. Each edge is associated with at least one byte value such that each path from the root node to a leaf node through one or more edges defines a unique byte prefix for a byte-comparable sequence of byte values. The leaf node of each path is associated with a database location value. A record is accessed in the database using a database location value determined from referencing the trie index using a byte-comparable sequence of byte values of the record generated from a key of the record. A trie structure and byte ordered keys may be used for partition or row indices.

An organic electroluminescence device includes: a first emitting layer including a first host material, a first organic material, and a first dopant material; and a second emitting layer including a second host material and a second dopant material, in which the first host material, the first organic material, and the second host material are different compounds in structure and satisfy Numerical Formula 1 and Numerical Formula 2. Numerical Formula 1: T.sub.1(H1)>T.sub.1(H3), Numerical Formula 2: T.sub.1(H2)>T.sub.1(H3) (In Numerical Formula 1 and Numerical Formula 2, T.sub.1(H1), T.sub.1(H2), T.sub.1(H3) are triplet energies of the first host material, the first organic material, and the second host material, respectively.)

The present invention relates to a compound of formula (I) for use in organic electronic devices, a composition comprising a compound of formula (IV) and at least one compound of formula (IVa) to (IVd), an organic semiconductor layer comprising the compound or composition, an organic electronic device comprising the organic semiconductor layer, and a display device comprising the organic electronic device.

##STR00001##

A composition for manufacturing an organic electronic device includes at least three organic functional materials H1, H2, and H3, and at least one organic solvent. The organic functional materials H1 and H2 can form a type II semiconductor heterojunction structure. A LUMO value of the organic functional material H3 is greater than or equal to that of the organic functional materials H1 and H2, and a HOMO value thereof is less than or equal to that of the organic functional materials H1 and H2.

The compound represented by formula (1):

##STR00001##

wherein symbols are as defined in the description, provides an organic electroluminescence device having a device performance further improved.

An organic EL display device includes an anode and a cathode and includes a blue organic EL device, a green organic EL device, and a red organic EL device. The blue organic EL device includes a first emitting layer. The green organic EL device includes a second emitting layer. The red organic EL device includes a third emitting layer. The organic EL devices include a fourth emitting layer as a common layer. The fourth emitting layer is in direct contact with each of the emitting layers). The first emitting layer contains a compound represented by a formula (1) and having at least one group represented by a formula (11). The fourth emitting layer contains a second compound represented by a formula (2).

##STR00001##

Provided is an organic light emitting device including a light emitting layer comprising a compound of Chemical Formula 1 and a first organic material layer comprising a compound of Chemical Formula 2:

##STR00001## wherein: Cy1 to Cy5 are each independently one selected from among a substituted or unsubstituted: aromatic hydrocarbon ring, aliphatic hydrocarbon ring, and aromatic hetero ring, or a ring in which two or more rings selected from the above group are fused, one or more of Cy1 to Cy5 are a ring of Chemical Formula 1-A:

##STR00002## one to three of a* to d* are a position fused to or linked to Chemical Formula 1;

##STR00003## L1 to L3 are each independently a direct bond or a substituted or unsubstituted: arylene or divalent heterocyclic group; and Ar1 and Ar2 are each independently a substituted or unsubstituted: aryl or heterocyclic group.

Embodiments provide a heterocyclic compound, a light-emitting device that includes the heterocyclic compound, and an electronic apparatus that includes the light-emitting device. The light-emitting device includes a first electrode, a second electrode facing the first electrode, an interlayer between the first electrode and the second electrode and including an emission layer, and at least one of the heterocyclic compound. The heterocyclic compound is represented by Formula 1, which is explained in the specification:

##STR00001##

Provided is an organic light emitting device including an anode; a cathode; a light emitting layer between the anode and the cathode; a first organic material layer between the light emitting layer and the anode; and a second organic material layer between the light emitting layer and the cathode, wherein the first organic material layer comprises a compound of Chemical Formula 1, the light emitting layer comprises a compound of Chemical Formula 2, the second organic material layer comprises a compound of Chemical Formula 3, and Chemical Formula 1 and Chemical Formula 3 satisfy one or more of <Equation 1> to <Equation 3>:

##STR00001##

|E.sub.L1|<E.sub.L3|  <Equation 1>

E.sub.s1>E.sub.s3  <Equation 2>

E.sub.T1>E.sub.T3  <Equation 3>

A novel light-emitting element is provided. A light-emitting element with a long lifetime is provided. A light-emitting element with high emission efficiency is provided. In the light-emitting element, an EL layer includes a hole-injection layer, a first hole-transport layer, a second hole-transport layer, a third hole-transport layer, a light-emitting layer, a first electron-transport layer, and a second electron-transport layer in this order; the hole-injection layer includes an organic acceptor; the LUMO level of the host material is higher than that of the first electron-transport layer; the LUMO level of the second electron-transport layer is higher than that of the first electron-transport layer; the host material is a substance including a condensed aromatic ring skeleton; and the first and second electron-transport layers each include a substance having a heteroaromatic ring skeleton.