The present invention provides a heterocyclic compound of the following general formula (I): wherein X and Y are different from each other and represent a halogen atom selected from among a chlorine atom, bromine atom and iodine atom, or CF3SO3−, CH3SO3−, C6H5SO3− or CH3C6H4SO3−; R1 represents an optionally substituted monovalent aliphatic hydrocarbon group having two or more carbon atoms; one of A1 and A2 represents —S—, —O—, —Se— or Te—, while the other represents —N═, —P═ or —Si(R2)═, wherein R2 represents a hydrogen atom, an optionally substituted monovalent hydrocarbon group, a halogen atom, an amino group or a carbonyl group; and one of two linkages each represented by a solid line and a dashed line is a single bond, while the other is a double bond.