Organic light-emitting device

An organic light-emitting device comprising:

• a first electrode;
• a second electrode facing the first electrode;
• and
• an organic layer between the first electrode and the second electrode and comprising an emission layer,
• wherein the emission layer comprises a host and a dopant,
• wherein the host comprises at least one compound selected from a phosphine oxide-based compound, a pyrimidine-containing compound, a triazine-containing compound, and a cyano group-containing compound, and the dopant satisfies Equation 1:
• |ED, S1−ED, T1|≤0.2 eV, Equation 1
• wherein, in Equation 1,
• ED, S1 refers to a singlet state energy level (eV) of the dopant;
• and
• ED, T1 refers to a triplet state energy level (eV) of the dopant, and
• an electroluminescence (EL) spectrum of the organic light-emitting device satisfies Equation 2 and Equation 3:
• EL(λ=420 nm)/EL(λ=MAX)<0.1 Equation 2
• Δ(MAX)<470 nm, Equation 3
• wherein, in Equations 2 and 3,
• EL(λ=420 nm) refers to an EL intensity at an emission wavelength of 420 nm;
• EL(λ=MAX) refers to an EL intensity at a maximum emission wavelength;
• and
• λ(MAX) refers to a maximum emission wavelength.