Application of coumarin derivative triplet photosensitizers in photolithography

In this study, coumarin derivatives, Coumarin-0 and Coumarin-Ir, are prepared. The photophysical process of charge transfer of Coumarin-Ir molecules is demonstrated by using steady-state/transient spectroscopy and density functional theory. The triplex electron transfer in Coumarin-Ir/Iod photoinitiation system proves the existence of intermolecular REDOX reactions. Coumarin-Ir acts as the donor to transfer electrons into iodonium salt (Iod), initiating the efficient REDOX electron transfer process. It has also been proved that the introduction of the Ir^Ⅲ atom in coumarin derivatives can effectively promote the photopolymerization efficiency, so that the monomer has higher double bond conversion efficiency in free radical polymerization (FRP) and excellent polymerization rate in cationic polymerization (CP). The results of photolithography experiments show that the low solid content ratio photoinitiated system can achieve high-resolution linewidth more effectively, which provides guidance for the construction of an appropriate photolithography ratio.