An organic light-emitting diode includes: a first electrode, a light-emitting stack thereon including, sequentially stacked: a hole transport layer (HTL) including an HTL material, a blue light-emitting layer including: a blue host material (BHM) and a blue fluorescent dopant (BFD) material, and an electron transport layer (ETL) including an ETL material, and a second electrode on the light-emitting stack, wherein the BFD material has a higher LUMO, a higher HOMO, and a lower singlet energy than the BHM, the HTL material has a higher HOMO than the BHM and the BFD material, a difference in HOMO between the HTL material and the BFD material is 0.1 eV or less, the ETL material has a higher LUMO than the BHM and the BFD material, and a difference in LUMO between the ETL material and the BFD material is 0.1 eV or less.