A polymer comprising; at least one structural unit, the at least one structural unit including a moiety represented by Chemical Formula 1, wherein, in Chemical Formula 1, Ar 1 is thienothiophene, thienoselenophene, thienotellurophene, a substituted or unsubstituted benzofuran, a substituted or unsubstituted benzothiophene, a substituted or unsubstituted benzoselenophene, or a substituted or unsubstituted benzotellurophene, Ar 2 and Ar 3 are each independently a substituted or unsubstituted furan, a substituted or unsubstituted thiophene, a substituted or unsubstituted selenophene, or a substituted or unsubstituted tellurophene, L 1 and L 2 are each independently a single bond, a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C6 to C30 arylene group, a substituted or unsubstituted C3 to C30 heterocyclic group, a fused ring thereof, or a combination thereof, R 1 to R 6 are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C2 to C30 alkenyl group, a substituted or unsubstituted C2 to C30 alkynyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkenyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C3 to C30 cycloheteroalkyl group, a substituted or unsubstituted C3 to C30 cycloheteroalkenyl group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C7 to C30 alkylaryl group, a substituted or unsubstituted C6 to C30 aryloxy group, a substituted or unsubstituted C3 to C30 heterocyclic group, a halogen, a cyano group, or a combination thereof, and * is a linking point, wherein the term "substituted" refers to replacement of hydrogen of a compound by a substituent selected from a halogen atom, a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C7 to C30 arylalkyl group, a C1 to C30 alkoxy group, a C1 to C20 heteroalkyl group, a C3 to C20 heteroaryl group, a C3 to C20 heteroarylalkyl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C15 cycloalkynyl group, a C3 to C30 heterocycloalkyl group, and a combination thereof. at least one structural unit, the at least one structural unit including a moiety represented by Chemical Formula 1, wherein, in Chemical Formula 1, Ar 1 is thienothiophene, thienoselenophene, thienotellurophene, a substituted or unsubstituted benzofuran, a substituted or unsubstituted benzothiophene, a substituted or unsubstituted benzoselenophene, or a substituted or unsubstituted benzotellurophene, Ar 2 and Ar 3 are each independently a substituted or unsubstituted furan, a substituted or unsubstituted thiophene, a substituted or unsubstituted selenophene, or a substituted or unsubstituted tellurophene, L 1 and L 2 are each independently a single bond, a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C6 to C30 arylene group, a substituted or unsubstituted C3 to C30 heterocyclic group, a fused ring thereof, or a combination thereof, R 1 to R 6 are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C2 to C30 alkenyl group, a substituted or unsubstituted C2 to C30 alkynyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkenyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C3 to C30 cycloheteroalkyl group, a substituted or unsubstituted C3 to C30 cycloheteroalkenyl group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C7 to C30 alkylaryl group, a substituted or unsubstituted C6 to C30 aryloxy group, a substituted or unsubstituted C3 to C30 heterocyclic group, a halogen, a cyano group, or a combination thereof, and * is a linking point, wherein the term "substituted" refers to replacement of hydrogen of a compound by a substituent selected from a halogen atom, a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C7 to C30 arylalkyl group, a C1 to C30 alkoxy group, a C1 to C20 heteroalkyl group, a C3 to C20 heteroaryl group, a C3 to C20 heteroarylalkyl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C15 cycloalkynyl group, a C3 to C30 heterocycloalkyl group, and a combination thereof.