An efficient iodination reaction of electron deficient heterocycles is described. The reaction utilizes (KOBu)-Bu-t as an initiator and likely proceeds by a radical anion propagation mechanism. This new methodology is particularly effective for functionalization of building blocks for electron transport materials. Its utility is demonstrated with the synthesis, of a new perylenediimide-thiazole non-fullerene acceptor capable of delivering a power conversion efficiency : of 4.5% in a bulk-heterojunction organic solar cell.