Light-emitting element using spirofluorene derivative and electronic appliance

[0080]In Embodiment Mode 1, a concept of a light-emitting element of the present invention will be explained.

[0081]In recent years, the present inventors have focused on phosphorescent compounds to achieve high performance of light-emitting elements and examined light-emitting elements using a wide variety of phosphorescent compounds. As one result thereof, the present inventors have found that by using a spiro-9,9′-bifluorene derivative to which one amino group is bonded is used, a light-emitting element containing a phosphorescent compound can provide light emission with very high efficiency compared to light-emitting elements using a phosphorescent compound which have been reported so far.

[0082]Through the property evaluation made by the present inventors, it was found that the T1 level of the spiro-9,9′-bifluorene derivative is high. That is, it was found that triplet excitation energy is difficult to transfer from other layers to a layer including the spiro-9,9′-bifluorene derivat

[0088]In Embodiment Mode 2, a structure of a light-emitting element of the present invention will be explained with reference to FIG. 1.

[0089]FIG. 1 is a view illustrating a light-emitting element having a layer 120 containing an organic compound between a first electrode 101 and a second electrode 104. The layer 120 containing an organic compound includes a first layer 102 containing a spiro-9,9′-bifluorene derivative and a second layer 103 containing a phosphorescent compound.

[0090]Here, the second layer 103 containing a phosphorescent compound is preferably a layer in which a substance with triplet excitation energy larger than that of the phosphorescent compound is used as a host material and the phosphorescent compound is dispersed as a guest material. Dispersing the phosphorescent compound which is a substance serving as an emission center can prevent light emitted from the phosphorescent compound from being quenched due to the concentration.

[0091]A phosphorescent compound is not

[0162]In Embodiment Mode 3, a light-emitting element with different element structure from that of Embodiment Mode 2 is exemplified in which a plurality of first layers containing a spiro-9,9′-bifluorene derivative and second layers containing a phosphorescent compound are provided and each of second layers containing phosphorescent compounds emits light. Accordingly, light that is a combination of light emitted from the plurality of light-emitting layers can be obtained. In Embodiment Mode 3, a mode of the light-emitting element including a plurality of first layers containing spiro-9,9′-bifluorene derivatives and second layers containing phosphorescent compounds will be explained with reference to FIG. 2.

[0163]A light-emitting element in FIG. 2 includes a layer A 203 containing an organic compound and a layer B 206 containing an organic compound between a first electrode 201 and a second electrode 202. The layer A 203 containing an organic compound includes a first layer 212 containi