4,9-Bis(5-bromo-2-thienyl)-2,7-bis(2-octyldodecyl)-benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone is an intermediate in the synthesis of P(NDI20D-T2). 4,9-Bis(5-bromo-2-thienyl)-2,7-bis(2-octyldodecyl)-benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone is also used in the synthetic preparation of naphthalenediimide-benzothiadiazole copolymer semiconductors for air-stable ambipolar charge transport.