Polymer and organic solar cell comprising same

A polymer comprising:

• a first unit represented by the following Chemical Formula 1;
• and
• a second unit represented by the following Chemical Formula 2:
• in Chemical Formulae 1 and 2,
• X, X′, X″, and X′″ are the same as or different from each other, and are each independently S or Se,
• A1 and A2 are the same as or different from each other, and are each independently hydrogen;
• or fluorine,
• A3 and A4 are the same as or different from each other, and are each independently hydrogen;
• fluorine;
• a substituted or unsubstituted alkyl group;
• a substituted or unsubstituted aryl group;
• or a substituted or unsubstituted heterocyclic group,
• R1 to R8 are the same as or different from each other, and are each independently hydrogen;
• deuterium;
• a halogen group;
• a hydroxy group;
• a substituted or unsubstituted alkyl group;
• a substituted or unsubstituted alkoxy group;
• a substituted or unsubstituted aryl group;
• or a substituted or unsubstituted heterocyclic group, and
• a1 to a4 are each an integer of 0 or 1.