Light-emitting devices

Abstract

To provide light-emitting devices with high luminous efficiency and reliability. [Solution] A light-emitting device comprising a host material and a guest material in the light-emitting layer. The host material is It has the function of converting triplet excitation energy into light emission, and the guest material emits fluorescence. The molecular structure of the material is a structure having a luminescent group and a protecting group, and the protecting group is present in one molecule of the guest material. Contains 5 or more. By introducing protecting groups into the molecule, the host material is transferred to the guest material. It suppresses triplet excitation energy transfer via the Küster mechanism. The protecting group is an alkyl group. , branched alkyl groups are used. By using a material having a 5-membered ring skeleton as the host material, This allows for the creation of light-emitting devices with improved luminescence efficiency.

Claims

[Claim 1] A light-emitting device having a light-emitting layer between a pair of electrodes, The light-emitting layer comprises a first material and a second material. The first material is capable of converting triplet excitation energy into light emission and has a five-membered ring skeleton. The second material is capable of converting singlet excitation energy into light emission and has a light phose and five or more protecting groups. The aforementioned luminescent group is a condensed aromatic ring or a condensed heteroaromatic ring, Each of the five or more protecting groups independently has one of the following: an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms. A light-emitting device in which the T1 level of the first material is higher than the S1 level of the second material.

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