A polymer comprising a unit represented by the following Formula 103, wherein, the polymer comprising the unit represented by Formula 103 is a homopolymer: in Formula 103, L2 to L5 are the same as or different from each other, and are each independently a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, Ar1 to Ar3 are the same as or different from each other, and are each independently a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted aryloxy group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, R1 to R5 are the same as or different from each other, and are each independently hydrogen; deuterium; a halogen group; a hydroxyl group; a nitrile group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, r4 and r5 are each an integer from 1 to 3, when r4 and r5 are each 2 or more, two or more R4's and R5's are each the same as or different from each other, m1 is a repeating number of the unit, and an integer from 1 to 10,000, L101 is a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b101 is an integer from 1 to 9, and when b101 is 2 or more, two or more L101's are the same as or different from each other. L2 to L5 are the same as or different from each other, and are each independently a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, Ar1 to Ar3 are the same as or different from each other, and are each independently a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted aryloxy group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, R1 to R5 are the same as or different from each other, and are each independently hydrogen; deuterium; a halogen group; a hydroxyl group; a nitrile group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, r4 and r5 are each an integer from 1 to 3, when r4 and r5 are each 2 or more, two or more R4's and R5's are each the same as or different from each other, m1 is a repeating number of the unit, and an integer from 1 to 10,000, L101 is a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b101 is an integer from 1 to 9, and when b101 is 2 or more, two or more L101's are the same as or different from each other.