Provided is an organic light-emitting device comprising an anode, a cathode, and a light-emitting layer provided between the anode and the cathode, wherein the light-emitting layer comprises a first compound of Chemical Formula 1 and a second compound of Chemical Formula 2: wherein: A is Chemical Formula 1a or 1b: Ar1 and Ar2 are each independently a C6-60 aromatic ring or a C2-60 heteroaromatic ring, and Ar1 and Ar2 are unsubstituted, or substituted with C1-60 alkyl, C6-60 aryl, or C2-60 heteroaryl; Ar′1 and Ar′2 are each independently substituted or unsubstituted C6-60 aryl or substituted or unsubstituted C2-60 heteroaryl; provided that a1+b1+c1+d+e+f is 1 or more; or a2+b2+c2+d+e+f is 1 or more; R′1 and R′2 are each independently hydrogen, deuterium, C1-60 alkyl, C6-60 aryl, or C2-60 heteroaryl; and r and s are each independently 0 to 7.