Enhancement of two-photon initiation efficiency based on conjugated phenothiazine and carbazole derivatives

A series of new initiators with a conjugated A–π–D–π–A structure of phenothiazine and carbazole derivatives were designed and synthesized to satisfy the demand for novel high-efficiency two-photon polymerization initiators. Moreover, the optical properties and two-photon polymerization properties of such new initiators were investigated. It was found that the two-photon absorption cross section of the initiators with the best performance can reach 1315 GM at 780 nm, and the scanning speed could reach 14,000 μm s −1 at a laser energy of 30 mW. When the wavelength was 810 nm, the absorption cross-section could reach up to 1667 GM. By adjusting the laser power and scanning speed, two-photon polymerization can be achieved within a large range of parameters, and complete and clear three-dimensional structures can be obtained.