Benzacephenanthrylene is an organic compound with the chemical formula C20H12. It is a polycyclic aromatic hydrocarbon (PAH) made of four benzene rings around a 5-membered ring. Benzacephenanthrylene is an organic compound with the chemical formula C20H12. It is a polycyclic aromatic hydrocarbon (PAH) made of four benzene rings around a 5-membered ring.