According to an article (English) in the Libya Herald dated 20 March 2013 and a press release (Arabic) from the Central Bank of Libya, the new 20-dinar note was issued on 31 March 2013. The orange-colored note shows a school in Ghadames on the front and Al-Ateeq mosque in Oujlah on the back.
Courtesy of Antje Maroussi and Eyad Alai.