'A well-lit area' is the correct sentence. 'Well- lit' is a compound adjective and it is used to describe the noun 'area'. The compound adjective in this sentence is composed of an 'adverb' (well) + past participle (lit). However, 'lighted' is also used for the past tense and past participle, especially in front of nouns: 'a lighted candle, cigarette, match, etc.' The opposite of 'lighted' is 'unlit'.

Both are correct, but there is a subtle difference: "lighted" is historically used in literature sometimes for rhetoric's sake (Hemingway has this short story A Clean, Well-Lighted Place), while "lit" is more often used in today's common speech.

"It is safer to be in a well-lit area" Lighted is incorrect~ :)