A modifier represented by the following Formula 1: in Formula 1, R 1 is deuterium; or an alkyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is substituted with a substituent X or unsubstituted, where the substituent X is selected from the group consisting of deuterium, halogen, a hydroxyl group, a nitro group, a cyano group, an alkyl group of 1 to 30 carbon atoms, an alkylsilyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, an alkoxy group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, and a heterocycle of 3 to 30 carbon atoms, R 2 is a hydrogen atom; or -Si 3, where R is an alkyl group of 1 to 10 carbon atoms, R 3 and R 4 are each independently a substituent represented by the following Formula 1a, R 5 is a single bond; an alkylene group of 1 to 20 carbon atoms; or a cycloalkylene group of 3 to 20 carbon atoms, A is S or O, B is N or S, if B is S, R 1 is an alkyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is substituted with a heterocycle of 3 to 30 carbon atoms or a nitro group among the substituent X; or a heteroalkyl group of 1 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is unsubstituted, where only R 3 is present among R 3 and R 4, where R 3 is a substituent represented by the following Formula 1a: in Formula 1a, R 6 is a single bond; or an alkylene group of 1 to 10 carbon atoms, R 7 and R 8 are each independently an alkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, or an aryl group of 6 to 30 carbon atoms, and n is an integer selected from 1 to 3. R 1 is deuterium; or an alkyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is substituted with a substituent X or unsubstituted, where the substituent X is selected from the group consisting of deuterium, halogen, a hydroxyl group, a nitro group, a cyano group, an alkyl group of 1 to 30 carbon atoms, an alkylsilyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, an alkoxy group of 1 to 30 carbon atoms, a heteroalkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, and a heterocycle of 3 to 30 carbon atoms, R 2 is a hydrogen atom; or -Si 3, where R is an alkyl group of 1 to 10 carbon atoms, R 3 and R 4 are each independently a substituent represented by the following Formula 1a, R 5 is a single bond; an alkylene group of 1 to 20 carbon atoms; or a cycloalkylene group of 3 to 20 carbon atoms, A is S or O, B is N or S, if B is S, R 1 is an alkyl group of 1 to 30 carbon atoms, an alkenyl group of 2 to 30 carbon atoms, an alkynyl group of 2 to 30 carbon atoms, a heteroalkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is substituted with a heterocycle of 3 to 30 carbon atoms or a nitro group among the substituent X; or a heteroalkyl group of 1 to 30 carbon atoms, or a heterocycle of 3 to 30 carbon atoms, which is unsubstituted, where only R 3 is present among R 3 and R 4, where R 3 is a substituent represented by the following Formula 1a: R 6 is a single bond; or an alkylene group of 1 to 10 carbon atoms, R 7 and R 8 are each independently an alkyl group of 1 to 30 carbon atoms, a cycloalkyl group of 5 to 30 carbon atoms, or an aryl group of 6 to 30 carbon atoms, and n is an integer selected from 1 to 3.