Electron-phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots

Boyang Wang; Zhihong Wei; Laizhi Sui; Jingkun Yu; Baowei Zhang; Xiaoyong Wang; Shengnan Feng; Haoqiang Song; Xue Yong; Yuxi Tian; Bai Yang; Siyu Lu

doi:10.1038/s41377-022-00865-x

Electron-phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots

Light Sci Appl. 2022 Jun 6;11(1):172. doi: 10.1038/s41377-022-00865-x.

Authors

Boyang Wang^#¹, Zhihong Wei^#², Laizhi Sui^#³, Jingkun Yu¹, Baowei Zhang⁴, Xiaoyong Wang⁵, Shengnan Feng⁵, Haoqiang Song¹, Xue Yong⁶, Yuxi Tian⁷, Bai Yang⁸, Siyu Lu⁹

Affiliations

¹ Green Catalysis Center, and College of Chemistry, Zhengzhou University, 450000, Zhengzhou, China.
² Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Vehicle Emissions Control, Nanjing University, 210023, Nanjing, China.
³ State Key Lab of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023, Dalian, China.
⁴ Nanochemistry Department, Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163, Genova, Italy.
⁵ School of Physics, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
⁶ Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK.
⁷ Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Jiangsu Key Laboratory of Vehicle Emissions Control, Nanjing University, 210023, Nanjing, China. tyx@nju.edu.cn.
⁸ State Key Lab of Supramolecular Structure and Materials, College of Chemistry, Jilin University, 130012, Changchun, China.
⁹ Green Catalysis Center, and College of Chemistry, Zhengzhou University, 450000, Zhengzhou, China. sylu2013@zzu.edu.cn.

^# Contributed equally.

Abstract

Due to the complex core-shell structure and variety of surface functional groups, the photoluminescence (PL) mechanism of carbon dots (CDs) remain unclear. o-Phenylenediamine (oPD), as one of the most common precursors for preparing red emissive CDs, has been extensively studied. Interestingly, most of the red emission CDs based on oPD have similar PL emission characteristics. Herein, we prepared six different oPD-based CDs and found that they had almost the same PL emission and absorption spectra after purification. Structural and spectral characterization indicated that they had similar carbon core structures but different surface polymer shells. Furthermore, single-molecule PL spectroscopy confirmed that the multi-modal emission of those CDs originated from the transitions of different vibrational energy levels of the same PL center in the carbon core. In addition, the phenomenon of "spectral splitting" of single-particle CDs was observed at low temperature, which confirmed these oPD-based CDs were unique materials with properties of both organic molecules and quantum dots. Finally, theoretical calculations revealed their potential polymerization mode and carbon core structure. Moreover, we proposed the PL mechanism of red-emitting CDs based on oPD precursors; that is, the carbon core regulates the PL emission, and the polymer shell regulates the PL intensity. Our work resolves the controversy on the PL mechanism of oPD-based red CDs. These findings provide a general guide for the mechanism exploration and structural analysis of other types of CDs.

Abstract

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