Photoacid generators comprising a moiety of formula (1): wherein: Ar1 is a substituted or unsubstituted aryl group; R1 is an alkyl or aryl group, each of which may be substituted or unsubstituted, wherein Ar1 and R1 are optionally connected together by a single bond or a divalent linking group to form a ring; Y is a single bond or a divalent group; and * is the point of attachment of the moiety to another atom of the photoacid generator. The photoacid generator compounds find particular use in photoresist compositions that can be used to form lithographic patterns for the formation of electronic devices.