Brief: Ascent Solar Technologies says CFO William Gregorak resigned
May 15 (Reuters) - Ascent Solar Technologies Inc ASTI.O : * Says William M. Gregorak, its chief financial officer, has resigned from his position effective may 13, 2015 * Says Victor Lee, co's chief executive officer, will serve as the company's interim principal financial officer * Source text for Eikon ID:nEOL7gBWn5 * Further company coverage ASTI.O ((Bengaluru Newsroom; +1 646 223 8780))