Developing high-efficiency photoinitiation systems by Leveraging highly Matched Interplays between photosensitizer and photoinitiator for enhanced energy transfer

Synthesizing highly compatible photosensitizer provides new directions for constructing high-efficiency photoinitiation systems (PSs). Here, a 2,4-Bis(4-(diethylamino)benzylidene)cyclobutanone (C4) was synthesized and used to form a three-component PSs (C4/HABI/MBO) with a biimidazole (HABI), 2-mercaptobenzoxazole (MBO). The photosensitizer has a more efficient energy transfer properties attributed to the higher fluorescence emission capacity, narrower energy band gap, lower free energy of electron transfer (ΔG_et) and improved matching with photoinitiator. Meanwhile, a double-cycle reaction mechanism is proposed, in which the improved matching seems to encourage this cycle to occur. As a result, the C4/HABI/MBO photoinitiation system well improved the diffraction efficiency of photopolymers up to 96% and demonstrated promising performance in recording and reproducing reflection holograms, which provide a new research idea for designing photoinitiation system.