Direct population of triplet excited states through singlet–triplet transition for visible-light excitable organic afterglow. Issue 19 (17th April 2019)

• Record Type: Journal Article
• Authors: Yuan, Jie; Chen, Runfeng; Tang, Xingxing; Tao, Ye; Xu, Shen; Jin, Lu; Chen, Cailin; Zhou, Xinhui; Zheng, Chao; Huang, Wei
• Is Part Of: Chemical science. Volume 10:Issue 19(2019)
• Page Start: 5031
• Page End: 5038
• Publication Date: 2019-04-17
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8sc05198d
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Direct population of triplet states via singlet-to-triplet absorption red-shifts the excitation wavelength and improves the organic afterglow efficiency under ambient conditions. Abstract : Invoking efficient afterglow in metal-free organic molecules represents an important material advancement. However, organic afterglow suffers from low intensity and efficiency and generally needs to be excited by UV light owing to its spin-forbidden phosphorescent nature that essentially requires facile intersystem crossing (ISC). Here, we propose a strategy to bypass the traditional ISC through facilitating singlet–triplet transition to directly populate triplet excited states from the ground state by combining synergetic effects of both heavy/hetero-atom incorporation and aromatic aggregation. Verified by systematic experimental and computational investigations, this unique singlet-to-triplet absorption results in a much improved organic afterglow quantum efficiency up to 9.5% with a prolonged lifetime of 0.25 s under visible-light irradiation. Fundamentally, this work illustrates for the first time the great potential of the direct population method to red-shift the excitation wavelength and improve the afterglow efficiency, offering important clues for the development of triplet-state involved organic optoelectronic technologies.