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 purifiication.Structural and spectral characterization indicated that they had similar carbon core structures but diffferent 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.

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

Green Catalysis Center,and College of Chemistry,Zhengzhou University,450000 Zhengzhou,China;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;State Key Lab of Molecular Reaction Dynamics,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,116023 Dalian,China;Nanochemistry Department,Istituto Italiano di Tecnologia(IIT),via Morego 30,16163 Genova,Italy;School of Physics,National Laboratory of Solid State Microstructures,Collaborative Innovation Center of Advanced Microstructures,Nanjing University,210093 Nanjing,China;Department of Chemistry,University of Sheffield,Sheffield S3 7HF,UK;State Key Lab of Supramolecular Structure and Materials,College of Chemistry,Jilin University,130012 Changchun,China

光：科学与应用（英文版）

[1]Boyang Wang;Zhihong Wei;Laizhi Sui;Jingkun Yu;Baowei Zhang;Xiaoyong Wang;Shengnan Feng;Haoqiang Song;Xue Yong;Yuxi Tian;Bai Yang;Siyu Lu-.Electron-phonon coupling-assisted universal red luminescence of o-phenylenediamine-based carbon dots)[J].光：科学与应用（英文版）,2022(07):1501-1514

Phenylenediamine,oPD,purifiication,diffferent

Electron,phonon,coupling,assisted,universal,phenylenediamine,carbon,dots,Due,complex,core,variety,surface,functional,groups,photoluminescence,PL,mechanism,CDs,remain,unclear,one,common,precursors,preparing,emissive,has,been,extensively,studied,Interestingly,emission,have,similar,characteristics,Herein,prepared,six,different,found,that,they,had,almost,same,absorption,after,Structural,spectral,characterization,indicated,structures,but,shells,Furthermore,single,spectroscopy,confirmed,multi,modal,those,originated,from,transitions,vibrational,energy,levels,center,addition,phenomenon,splitting,particle,was,observed,low,temperature,which,these,were,unique,materials,properties,both,organic,molecules,quantum,Finally,theoretical,calculations,revealed,their,potential,polymerization,mode,Moreover,proposed,emitting,regulates,intensity,Our,work,resolves,controversy,These,findings,provide,general,guide,exploration,structural,analysis,other,types

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