The present application relates to a nitrogen-containing compound. The structural formula of the nitrogen-containing compound is as shown in a Formula 1, in which a ring A and a ring B are each independently selected from a benzene ring or a fused aromatic ring with 10 to 14 ring-forming carbon atoms, and at least one of the ring A and the ring B is selected from the fused aromatic ring with 10 to 14 ring-forming carbon atoms; L is selected from a single bond, a substituted or unsubstituted arylene group with 6 to 30 carbon atoms, and a substituted or unsubstituted heteroarylene group with 3 to 30 carbon atoms; and Het is a substituted or unsubstituted nitrogen-containing heteroaryl group with 3 to 30 carbon atoms. The nitrogen-containing compound of the present application can improve the luminous efficiency of an organic electroluminescent device and the conversion efficiency of a photoelectric conversion device using the nitrogen-containing compound.