Effect of intrachain rotation of porphyrin molecules on luminescence efficiency in two kinds of low-doped porphyrin side-chain polymer films

摘要

Transient luminescent dynamics in two kinds of low-doped porphyrin side-chain polymer films, poly[por-phyrin acrylate-acrylonitrile] (p[(por)A-AN]) and poly[porphyrin acrylate-styrene] (p[(por)A-S]), were measured using time-resolved photoluminescence spectroscopy. The luminescence is shown to decay more rapidly with the decrease of the intrachain porphyrin comonomer concentration. We calculated the interaction potential energy between the intrachain porphyrin molecules by using the method of MM~+ force field. The results show that the intrachain aggregation of the porphyrin molecules can induce larger rotational barrier, slowing the nonradiative decay of the emissive exciton and leading to higher luminescence efficiency. The transient luminescence relaxation processes in p[(por)A-S] and p[(por)A-AN] films were numerically fitted with the theory of the exciton rotation diffusion. The experimental results are in good agreement with the theoretical analysis.