Design of D–π–A type photoacid generators for high efficiency excitation at 405 nm and 800 nm

New sulfonium salts with diphenylamino asymmetrically substituted stilbene as a D-π-A conjugated system have been synthesized. The resulting photoacid generators exhibit a highly efficient acid photogeneration process by either one-photon 405 nm or two-photon 800 nm excitation.