A light-emitting device with high resistance to heat in a fabrication process is provided. The light-emitting device includes an EL layer between an anode and a cathode. The EL layer includes at least a light-emitting layer and an electron-transport layer that includes a first electron-transport layer in contact with the light-emitting layer and a second electron-transport layer in contact with the first electron-transport layer. The first electron-transport layer includes a first heteroaromatic compound including at least one heteroaromatic ring. The second electron-transport layer includes a second heteroaromatic compound that includes at least one heteroaromatic ring and is different from the first heteroaromatic compound. The first heteroaromatic compound has a difference of 20° C. or less between the crystallization temperature (Tpc) of a powder state and the crystallization temperature (Ttc) of a thin film state. The second heteroaromatic compound has a difference of 100° C. or less between Tpc and Ttc.

Provided organic light emitting device (OLED) comprising compounds having Formula I:

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wherein rings A, B, C, D, E, and F are each independently a single or fused ring system, consisting of one or more 5-membered or 6-membered carbocyclic or heterocyclic rings; L.sup.1, L.sup.2, L.sup.3, L.sup.4, L.sup.5, and L.sup.6 are each independently optionally present or is selected from the group consisting of O, S, Se, BR, BRR′, NR, C═R, CRR′, SiRR′, P(O)R, and GeRR′; a, b, c, d, e and f are each 0 for not present or 1 for present; each of R, R′, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 is independently a hydrogen or a substituent; and any two of adjacent R, R′, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 can be joined or fused to form a ring. The compound is an ETL.

The present invention relates to a metal iridium complex and application thereof. The metal iridium complex has a structure as shown in the following formula (I). The compound provided in the present invention has the advantages of low sublimation temperature, great optical and electrical stability, high luminescence efficiency, long service life, and high color saturation, and can be used in organic light-emitting devices. In particular, the complex has the potential for application in the AMOLED industry as a red light-emitting phosphorescent material.

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Provided is an organometallic complex represented by general formula (1) below.

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In formula (1), X.sub.1 to X.sub.3 are each independently selected from a carbon atom and a nitrogen atom, and at least one of X.sub.1 to X.sub.3 is a nitrogen atom. The carbon atom has a hydrogen atom or a substituent. Y is an aryl group or a heterocyclic group. L is a bidentate ligand. When a plurality of L's are present, the plurality of L's may be the same or different. M is a metal atom selected from Ir, Pt, Rh, Os, and Zn. m represents an integer of 1 to 3, and n represents an integer of 0 to 2. R.sub.1 to R.sub.5 each represent a hydrogen atom or a substituent.

A spirobifluorene compound and a perovskite solar cell including the spirobifluorene compound are disclosed. More particularly, a spirobifluorene compound which can be used as a hole transport material of a perovskite solar cell is disclosed. A perovskite solar cell including the spirobifluorene compound as a hole transport material is further disclosed.

A light emitting device that includes a first electrode, a second electrode oppositely disposed to the first electrode, and an emission layer between the first electrode and the second electrode is provided. The emission layer includes an organometallic compound represented by Formula 1:

##STR00001##

A light emitting device that includes a first electrode, a second electrode facing the first electrode, and an emission layer between the first electrode and the second electrode is provided. The emission layer includes a first compound represented by Formula 1, and at least one of a second compound represented Formula H-1, a third compound represented Formula H-2, or a fourth compound represented Formula D-2, thereby exhibiting improved luminous efficiency characteristics.

A light emitting element includes a first electrode, a second electrode disposed on the first electrode, and an emission layer disposed between the first electrode and the second electrode. The emission layer may include a first compound represented by Formula 1, and at least one of a second compound, a third compound, and a fourth compound. The light emitting element including the first compound represented by Formula 1 exhibits high efficiency and a long lifespan.

##STR00001##

A light emitting element that includes a first electrode, a second electrode on the first electrode, and an emission layer between the first electrode and the second electrode is provided. The emission layer includes an organometallic compound represented by Formula 1. The light emitting element exhibits long lifespan properties.

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A novel display apparatus that is highly convenient, useful, or reliable is provided. The display apparatus includes a first electrode, a second electrode, a first unit, a second unit, and a first intermediate layer; the first unit is located between the second electrode and the first electrode; and the first unit contains a first light-emitting material EM1. The second unit is located between the second electrode and the first unit and contains a second light-emitting material EM2. The first intermediate layer is located between the second unit and the first unit. The first intermediate layer includes a first layer and a second layer; the first layer is located between the second unit and the second layer; the first layer contains an organic compound having a halogen group or a cyano group or a transition metal oxide; and the second layer contains a first organic compound AM2 having an electron-accepting property, a second organic compound DM having an electron-donating property, and a third organic compound BM having basicity.