Light-Emitting Element, Light-Emitting Device, Electronic Device, and Lighting Device

    公开(公告)号:US20180182330A1

    公开(公告)日:2018-06-28

    申请号:US15849003

    申请日:2017-12-20

    Abstract: A highly reliable light-emitting element that shows a novel degradation curve when driven is provided. The degradation curve of a light-emitting element with a long lifetime is represented by a function composed of two exponential functions, which is a linear combination of an exponential function expressing an initial degradation component and an exponential function expressing a long-term degradation component. The initial degradation component is represented by a stretched exponential function, and the long-term degradation component is represented by a single exponential function. When the proportion of the initial degradation component of the degradation curve represented by the function composed of two exponential functions is less than or equal to 0.25, preferably less than or equal to 0.20, and further preferably less than or equal to 0.15; a highly reliable light-emitting element is obtained.

    Light-emitting element, display device, electronic device, and lighting device

    公开(公告)号:US10714700B2

    公开(公告)日:2020-07-14

    申请号:US16513869

    申请日:2019-07-17

    Abstract: A light-emitting element having high emission efficiency which includes a fluorescent material as a light-emitting substance is provided. A light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a light-emitting layer. The light-emitting layer includes a host material and a guest material. The host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a singlet excitation energy level and a triplet excitation energy level. The guest material is capable of emitting fluorescence. The triplet excitation energy level of the host material is higher than a triplet excitation energy level of the guest material.

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