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Updated: Jan 29, 2026

Fluorescence Lifetime Macro Imager for Biomedical Applications
Published on: April 7, 2023
The methylation effect in prolonging the pure organic room temperature phosphorescence lifetime
Zhu Mao1, Zhan Yang1, Zhenguo Fan1
1PCFM Lab , GDHPPC Lab , Guangdong Engineering Technology , Research Center for High-performance Organic and Polymer Photo-electric, Functional Films , State Key Laboratory of OEMT , School of Chemistry , Sun Yat-Sen University , Guangzhou 510275 , China.
Abstract:
Prolonging the phosphorescence lifetime of pure organic phosphorescent materials by a methyl-substitution strategy is described. We present a chemical strategy for improving the phosphorescence lifetime of triplet excitons under ambient conditions by incorporating methyl groups into the chemical structures. This is observed by a long-lived phosphorescence lifetime of up to 0.83 s detected for methylated 9-(4-(mesitylsulfonyl)phenyl)-9H-carbazole (3M), compared to 0.36 s for 9-(4-(phenylsulfonyl)phenyl)-9H-carbazole (0M) without any methyl groups. Additionally, enhanced phosphorescence efficiency can be obtained at an appropriate methylation degree, because of the smaller ΔE ST (singlet and triplet energy gap) and ΔE TT* (normal phosphorescence and long-lived phosphorescence energy gap). A comprehensive investigation on the packing mode in the crystalline state reveals that the methyl groups occupy the free volume and result in a suppression of non-radiative decay, accounting for the enhanced phosphorescence lifetime.
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