Einstein got 1921 Nobel a year late as 'no one met criteria'

Albert Einstein received the 1921 Nobel Prize in Physics in 1922 as "none of the year's nominations met the criteria" outlined in the will of its founder Alfred Nobel. The Nobel Foundation thus reserved the award for one year as per the rules. Further, Einstein was awarded the Nobel for 'photoelectric effect' and not for his energy-mass equivalence equation E=mc².