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Xiao L, Wang Z, Zhang C, Xie X, Ma H, Peng Q, An Z, Wang X, Shuai Z, Xiao M. Long Persistent Luminescence Enabled by Dissociation of Triplet Intermediate States in an Organic Guest/Host System. J Phys Chem Lett 2020; 11:3582-3588. [PMID: 32302138 DOI: 10.1021/acs.jpclett.0c00880] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Organic guest/host systems with long persistent luminescence benefiting from the formation of a long-lived charge-separated state have recently been demonstrated. However, the photogeneration mechanism of such key charge-separated states remains elusive. Here, we report the identification of intermediate triplet states with mixed local excitation and charge-transfer character that connect the initial photoexcited singlet states and the long-lived charge-separated states. Using time-resolved optical spectroscopy, we observe the intersystem crossing from photoexcited singlet charge-transfer states to triplet intermediate states on a time scale of ∼52 ns. Temperature-dependent measurements reveal that the long-lived triplet intermediate states ensure a relatively high efficiency of diffusion-driven charge separation to form the charge-separated state responsible for LPL emission. The findings in this work provide a rationale for the development of new LPL materials that may also improve our understanding of the mechanism of photon-to-charge conversion in many organic optoelectronic devices.
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Affiliation(s)
- Leixin Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhiwei Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiaoyu Xie
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Haibo Ma
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Qian Peng
- China Key Laboratory of Organic Solids and Beijing National Laboratory for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhongfu An
- Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Nanjing Tech University, Nanjing 211816, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Zhigang Shuai
- Department of Chemistry and MOE Key Laboratory of Organic Optoelectronics and Molecular Engineering, Tsinghua University, Beijing 10084, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
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Abstract
Long persistent luminescence (LPL) materials-widely commercialized as 'glow-in-the-dark' paints-store excitation energy in excited states that slowly release this energy as light. At present, most LPL materials are based on an inorganic system of strontium aluminium oxide (SrAl2O4) doped with europium and dysprosium, and exhibit emission for more than ten hours. However, this system requires rare elements and temperatures higher than 1,000 degrees Celsius during fabrication, and light scattering by SrAl2O4 powders limits the transparency of LPL paints. Here we show that an organic LPL (OLPL) system of two simple organic molecules that is free from rare elements and easy to fabricate can generate emission that lasts for more than one hour at room temperature. Previous organic systems, which were based on two-photon ionization, required high excitation intensities and low temperatures. By contrast, our OLPL system-which is based on emission from excited complexes (exciplexes) upon the recombination of long-lived charge-separated states-can be excited by a standard white LED light source and generate long emission even at temperatures above 100 degrees Celsius. This OLPL system is transparent, soluble, and potentially flexible and colour-tunable, opening new applications for LPL in large-area and flexible paints, biomarkers, fabrics, and windows. Moreover, the study of long-lived charge separation in this system should advance understanding of a wide variety of organic semiconductor devices.
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Rosspeintner A, Griesser M, Matsumoto I, Teki Y, Li G, Nelsen SF, Gescheidt G. EPR and ENDOR Studies of Dimeric Paracyclophane Radical Cations and Dications Containing Tri- and Pentamethylene-Bridged p-Phenylene Diamine Units. J Phys Chem A 2010; 114:6487-92. [DOI: 10.1021/jp100348v] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arnulf Rosspeintner
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Markus Griesser
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Isao Matsumoto
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Yoshio Teki
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Gaoquan Li
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Stephen F. Nelsen
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
| | - Georg Gescheidt
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstraβe 4/I, A-8010 Graz, Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558 Japan, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396
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