A light-emitting device includes: a first electrode; a second electrode; m emission units between the first electrode and the second electrode; and m−1 charge generation layer(s), each located between two adjacent emission units, and including m−1 n-type charge generation layer(s) and m−1 p-type charge generation layer(s). The m emission units each include a hole transport region, an emission layer, and an electron transport region. A first hole transport region in a first emission unit closest to the first electrode may include a hole transfer layer and a hole injection layer and/or a hole transport layer. The hole transfer layer may be a single layer consisting of an electron-transporting compound including a phosphine oxide group (P═O), a phosphine sulfide group (P═S), a π electron-deficient nitrogen-containing C1-C60 cyclic group, or any combination thereof. A highest occupied molecular orbital (HOMO) energy level of the hole transfer layer may be about −6.0 eV to about −5.3 eV.