The light-emitting element 250 illustrated in FIG. 3A includes a plurality of light-emitting units (a light-emitting unit 106 and a light-emitting unit 110) between a pair of electrodes (the electrode 101 and the electrode 102). One of the light-emitting units preferably has the same structure as the EL layer 100 illustrated in FIG. 1A. That is, it is preferable that the light-emitting element 150 illustrated in FIG. 1A include one light-emitting unit while the light-emitting element 250 include a plurality of light-emitting units. Note that the electrode 101 functions as an anode and the electrode 102 functions as a cathode in the following description of the light-emitting element 250; however, the functions may be interchanged in the light-emitting element 250.
In the light-emitting element 250 illustrated in FIG. 3A, the light-emitting unit 106 and the light-emitting unit 110 are stacked, and a charge-generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 110. Note that the light-emitting unit 106 and the light-emitting unit 110 may have the same structure or different structures. For example, it is preferable that a structure similar to that of the EL layer 100 be used in the light-emitting unit 110.
