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 pr...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.展开更多
The world is facing the grand challenges of balancing economic growth and environmental protection,urging the development of sustainable energy sources and more efficient energy consumption[1].To tackle these challeng...The world is facing the grand challenges of balancing economic growth and environmental protection,urging the development of sustainable energy sources and more efficient energy consumption[1].To tackle these challenges,new materials are in great demand.In this respect,semiconductor nanocrystals(NCs)have shown great potential in light harvesting applications such as photovoltaics.展开更多
Perovskite nanocrystals and quantum dots(QDs)have attracted great attention due to their potential in optical and optoelectronic applications,especially in ultra-high definition displays because of their high purity o...Perovskite nanocrystals and quantum dots(QDs)have attracted great attention due to their potential in optical and optoelectronic applications,especially in ultra-high definition displays because of their high purity of photo/electroluminescence(PL/EL)[1,2].Although the external quantum efficiency(EQE)of light-emitting diodes(LEDs)based on perovskite quantum dots(PeQDs)has been over 20%[3,4],another key problem,the PL/EL stability,still remains open.The thermal PL/EL quenching phenomenon,which is ubiquitously observed.展开更多
基金supported by the National Natural Science Foundation of China(52122308,21905253,51973200,22073046)the Natural Science Foundation of Henan(202300410372).
文摘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.
基金We are very much grateful to all the authors for their contributions to this exciting issue.We also thank all reviewers and the editorial board for organizing this special issue.
文摘The world is facing the grand challenges of balancing economic growth and environmental protection,urging the development of sustainable energy sources and more efficient energy consumption[1].To tackle these challenges,new materials are in great demand.In this respect,semiconductor nanocrystals(NCs)have shown great potential in light harvesting applications such as photovoltaics.
文摘Perovskite nanocrystals and quantum dots(QDs)have attracted great attention due to their potential in optical and optoelectronic applications,especially in ultra-high definition displays because of their high purity of photo/electroluminescence(PL/EL)[1,2].Although the external quantum efficiency(EQE)of light-emitting diodes(LEDs)based on perovskite quantum dots(PeQDs)has been over 20%[3,4],another key problem,the PL/EL stability,still remains open.The thermal PL/EL quenching phenomenon,which is ubiquitously observed.
