Polycarbonate resin and preparation method thereof

A polycarbonate resin, comprising:

• a unit of the following Chemical Formula 1;
• and
• a unit of the following Chemical Formula 2:
• wherein, in Chemical Formulae 1 and 2,
• Ar1 and Ar2 are the same as or different from each other, and are each independently a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group,
• R1 is hydrogen, deuterium, a halogen group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group,
• R2 and R3 are different from each other, and are each independently hydrogen, deuterium, a halogen group, a cyano group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted silyl group, an aryl group which is unsubstituted or substituted with deuterium, a halogen group, a hydroxyl group, a cyano group, an alkyl group, a cycloalkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylthio group, an alkylthio group, an aryl group, or a heteroaryl group, or a substituted or unsubstituted heteroaryl group,
• r1 is 1 or 2, and when r1 is 2, each R1 is the same as or different from each other,
• r2 and r3 are each an integer from 1 to 4, and when r2 is 2 to 4, two or more R2 are the same as or different from each other, and when r3 is 2 to 4, two or more R3 are the same as or different from each other,
• L1 and L2 are the same as or different from each other, and are each independently a substituted or unsubstituted arylene group,
• X1 to X8 are the same as or different from each other, and are each independently O or S,
• Z1 to Z4 are the same as or different from each other, and are each independently a substituted or unsubstituted alkylene group, or a substituted or unsubstituted cycloalkylene group, and
• a, b, c and d are the same as or different from each other, and are each independently an integer from 1 to 10, and when a and b are each 2 to 10, each of Z1-X1 and X2-Z2 are the same as or different from each other.