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

A light-emitting element comprising:

• a first electrode;
• an EL layer over the first electrode, the EL layer comprising:
• a light-emitting layer comprising a first substance and a second substance;
• and
• a second electrode over the EL layer,
• wherein an amount of the first substance is larger than an amount of the second substance in the light-emitting layer,
• wherein the second substance is capable to emit light,
• wherein light emission from average transition dipoles of the second substance in the light-emitting layer comprises:
• light emission from an x-component of the average transition dipoles in an x-direction, the x-component being a component of light emission parallel to the first electrode;
• light emission from a y-component of the average transition dipoles in a y-direction, the y-component being a component of light emission parallel to the first electrode;
• and
• light emission from a z-component of the average transition dipoles in a z-direction, the z-component being a component of light emission perpendicular to the first electrode,
• wherein a sum of a ratio of the light emission from the x-component to the whole light emission, a ratio of the light emission from the y-component to the whole light emission, and a ratio of the light emission from the z-component to the whole light emission, is 1,
• wherein the x-direction, the y-direction and the z-direction are orthogonal to each other,
• wherein a proportion of the z-component in the z-direction is a, and
• wherein a is greater than 0 and less than or equal to 0.2.