OEE is calculated with the formula (Availability)*(Performance)*(Quality)
Each of these factors should be bounded from 0 to 1, so the maximum OEE is also bounded by 1 (i.e., 100%). The only way to exceed 1 would be to have a different definition for the factors that is not bounded by 0 and 1.
No. OEE might not exceed 100%. Usually reason for exceeding 100% is wrong definition of Planned Production Time, not proper definition of maximum Rated Output or falsified reporting of First Time Through output.