Patent ID: 11917840
Assignee: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC H

Claim 0:
1. A light-emitting device comprising:
a first electrode;
a second electrode; and
an EL layer between the first electrode and the second electrode, the EL layer comprising a light-emitting layer,
wherein the light-emitting layer comprises an emission center substance,
wherein the first electrode and the second electrode overlap each other,
wherein one of the first electrode and the second electrode is a reflective electrode and the other is a semi-transmissive and semi-reflective electrode,
wherein Eave is an average of photon energy of an emission spectrum of the emission center substance,
wherein Eedge is an energy at an emission edge on a short wavelength side of the emission spectrum,
wherein Eem is a photon energy corresponding to a light having a wavelength λ,
wherein the wavelength λ is longer than a peak wavelength of the emission spectrum,
wherein an optical path length between the reflective electrode and the light-emitting layer is configured to (2n−1)λ/4 where n is a natural number, and
wherein the following formula (1) is satisfied:

Eave≤Eem≤0.95Eedge  (1).