Organic solar cell comprises at least one N,N-bis(fluorene-2-yl)-naphthalinetetracarboxydiimide compound (I). Organic solar cell comprises at least one N,N-bis(fluorene-2-yl)-naphthalinetetracarboxydiimide compound of formula (I). R1-R6 : H, halo, optionally substituted or optionally saturated 1-20C alkyl, 1-20C heteroalkyl, 1-20C alkenyl, 1-20C heteroalkenyl, 1-20C alkynyl, 1-20C heteroalkynyl, 6-20C aryl, 6-20C heteroaryl, optionally saturated carbocycle or heterocycle, where two adjacent R1-R6 is part of further optionally saturated, carbocyclic or heterocyclic ring comprising C, N, O, S, Si and Se. [Image].