Unlike most narrow bandgap non-fullerene acceptors (NFAs), IO-4Cl is a medium/wide bandgap n-type non-fullerene semiconductor bearing an electron rich indacenodithieno-[3,2-b]thiophene (also known as ITIC core). It has a similar structure to ITIC-4Cl (ITIC-DCl), however electron-accepting unit are composed of two carbonyl units, while ITIC-DCl has one carbonyl group and one more electron-withdrawing malononitrile group.
