I second this and would like to add that Persians are one of dozen of ethnicities that make up Iran including Turks/Azeris, Kurds, Arabs, Baluchs, Turkmens, Lors/Lurs, etc. [1] Referring to it as Persia/Persians is akin to ignoring vast majority of the people living there imho.
"Iran" has been the term people used inside to refer to the land/people for a very long time, but Shah officially requested the change from foreign governments in 1935.[2]