Two-photon Absorption Spectral Properties of Three-Branched Carbazole Dye for Polymerization Initiator: an Experimental and Theoretical Study

Understanding the two-photon spectral properties of photoinitiators is crucial for the advancements and applications of photopolymerization (PP) techniques, specifically focusing on two-photon polymerization (TPP) for three-dimensional printing (3DP). In this work, we have investigated a specific photoinitiator designated as TECEB, a three-branched carbazole-based compound used in TPP at visible wavelengths. The lack of detailed two-photon absorption (TPA) data for TECEB is now fulfilled with this one- and two-photon absorption investigation from the experimental and theoretical points of view. Femtosecond pulses were used to acquire the TPA cross-section (sigma(2)) spectra via the Z-scan technique. Using the Gaussian software package, quantum chemical calculations (QCC) were conducted with 36 different combinations, comprising 6 chemistry models and 6 basis sets. TECEB's TPA results clearly show that this compound has a strong potential to be used as polymeric solutions in 3DP-TPP, mainly due to its TPA cross section in the spectral region between 500 nm and 550 nm, with values up to 250 GM.