You might be interested in some previous threads on Iran and Persia:

• Why did the people and leaders of Iran not name their country Persia? Was the term "Persia" merely a western construct? - 19 comments, over 9 months old.
• This thread traces the usage of "Persia" and "Iran" from Antiquity onwards.
• When, and why did Persia stop being called Persia, and start to be called Iran? - 11 comments, over 1 year old.
• This talks about the 20th century history of the use of "Persia" and "Iran".
• What was the significance of the name change of Persia to Iran and Babylonians to Assyrian? - 9 comments, over 1 year old.
• Although this thread is mostly devoted to talking about culture and identity, there is a comment towards the middle with information about the use of "Persia" and "Iran" in western literature.

It has been Iran for a very long time. Since ancient times the Iranians have been calling their homeland Iran. In 1935 Reza Shah asked the world to call the land by its real name, Iran, and not Persia which came from the Greeks.

'Iran' is a native name for the country coming from the same root as the word 'aryan', being an identifier in Indo-European languages including Sanskrit. 'Persia' is the name of a region in Iran AKA 'Fars' which was the historic heartland of the Persians/Iranians