Carbazole isomers induce ultralong organic phosphorescence

Chen, Chengjian; Chi, Zhenguo; Chong, Kok Chan; Batsanov, Andrei S.; Yang, Zhan; Mao, Zhu; Yang, Zhiyong; Liu, Bin

Abstract

Commercial carbazole has been widely used to synthesize organic functional materials that have led to recent breakthroughs in ultralong organic phosphorescence1, thermally activated delayed fluorescence2,3, organic luminescent radicals4 and organic semiconductor lasers5. However, the impact of low-concentration isomeric impurities present within commercial batches on the properties of the synthesized molecules requires further analysis. Here, we have synthesized highly pure carbazole and observed that its fluorescence is blueshifted by 54 nm with respect to commercial samples and its room-temperature ultralong phosphorescence almost disappears6. We discover that such differences are due to the presence of a carbazole isomeric impurity in commercial carbazole sources, with concentrations <0.5 mol%. Ten representative carbazole derivatives synthesized from the highly pure carbazole failed to show the ultralong phosphorescence reported in the literature1,7,8,9,10,11,12,13,14,15. However, the phosphorescence was recovered by adding 0.1 mol% isomers, which act as charge traps. Investigating the role of the isomers may therefore provide alternative insights into the mechanisms behind ultralong organic phosphorescence1,6,7,8,9,10,11,12,13,14,15,16,17,18.

Citation

Chen, C., Chi, Z., Chong, K. C., Batsanov, A. S., Yang, Z., Mao, Z., Yang, Z., & Liu, B. (2021). Carbazole isomers induce ultralong organic phosphorescence. Nature Materials, 20(February 2021), 175-180. https://doi.org/10.1038/s41563-020-0797-2

• Journal Article Type: Article
• Acceptance Date: Aug 10, 2020
• Online Publication Date: Sep 21, 2020
• Publication Date: 2021-02
• Deposit Date: Oct 8, 2020
• Publicly Available Date: Mar 21, 2021
• Journal: Nature Materials
• Print ISSN: 1476-1122
• Electronic ISSN: 1476-4660
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: February 2021
• Pages: 175-180
• DOI: https://doi.org/10.1038/s41563-020-0797-2
• Public URL: https://durham-repository.worktribe.com/output/1254470