Engineering triangular carbon quantum dots with unprecedented narrow bandwidth emission for multicolored LEDs
Authors: Fanglong Yuan
Xiaohong Li
Ting Yuan
Laizhi Sui
Zhibin Wang
Shihe Yang
Zifan Xi
Louzhen Fan
Anmin Chen
Mingxing Jin
Yunchao Li
Zhan&#x27;ao Tan
Journal: Nature Communications (2018)
Discipline: Multidisciplinary
Keywords: Carbon quantum dots; optoelectronic applications; narrow bandwidth emission; triangular CQDs; quantum yield
Affiliations: College of Chemistry, Beijing Normal University, 100875, Beijing, China., Institute of Atomic and Molecular Physics, Jilin University, 130012, Changchun, China., State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, 116023, Dalian, China., State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, 102206, Beijing, China., College of Chemistry, Beijing Normal University, 100875, Beijing, China. ., State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, 102206, Beijing, China. ., Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 100029, Beijing, China. ., Guangdong Key Lab of Nano-Micro Material Research, School of Chemical Biology and Biotechnology, Shenzhen Graduate School, Peking University, 518055, Shenzhen, China. .

Abstract:  Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon's intrinsic merits of high stability, low cost, and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit their display applications. Here we demonstrate multicolored narrow bandwidth emission (full width at half maximum of 30 nm) from triangular CQDs with a quantum yield up to 54-72%. Detailed structural and optical characterizations together with theoretical calculations reveal that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs display good stability, high color-purity, and high-performance with maximum luminance of 1882-4762 cd m-2 and current efficiency of 1.22-5.11 cd A-1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes. 

Retracted: No

PubPeer comments:
 Part of the TEM images in Figure S28C of this paper and Figure 3A in a Nano Research paper (doi: 10.1007 s12274-019-2420-x) appear much similar than you would expect. Highlighted with the red closed area. Interestingly, the parts outside the red area are different. ![file] , 
 More data reuse between the two papers. ![file] ![file] , 
 FigureS28 a g, the red areas of the TEM background, much more similar than you would expect. Is there any expert who can confirm whether this may happen in the TEM image? ![file] , 
 #1 Phycodrys Adamsiae has noted similarities between the present Fig 3(b) S28(c) *[right]* and *[left]* 3(a) from [Yuan et al (2019)] , but I want to point out another. ![file] , 
 This nature communication paper has been on my list to comment on for some time. Especially since it is showing up in carbon dot review articles. I had several concerns with the TEM and the HAADF-STEM images. 1)The peer review file is an interesting read. One reviewer asked for a wider field of view to show more nanoparticles. In response, the authors suggest that these rather large nanoparticles become undetectable at lower magnifications and supported this claim by submitting a blank TEM image. Contrast does not seem to be an issue in the HAADF-STEM images submitted by the authors. In practice, one would have taken a lower magnification STEM image to find where the particles are located. Why wasnu2019t this submitted? 2) The support films is composed of amorphous carbon so repeating features in the back ground is extremely unlikely. The only exception would be artifacts by a poorly maintained CCD camera, but this doesn t look like a CCD artifact. 3) The loss of contrast from the support film around the particles makes little sense. Further, the editor should always ask for non-annotated TEM images for the SI. The drawn triangles make it difficult to see the transition from particle to background film. 4) The FFTs shown in figure s29 f-h are the same and do not correspond to the images shown in b-d. 5) The most striking imagery are the aberration-corrected STEM images of the carbon dots that demonstrate almost defect-free graphene crystalline structure . My issue with these images is a bit more difficult to explain. t -tHAADF-STEM or high angle annular dark field scanning transmission electron microscopy uses an annular (donut shaped) detector to form images by detecting highly scattered electrons. The intensity in the image is roughly proportional to the atomic number squared (Z-STEM). -tThe HAADF images are supposedly graphene nanoparticles composed of carbon supported by a ~3 nm thick carbon support film. Why is there so much atomic contrast? 6) The structures do not resemble layered graphene triangles as modeled but are likely pyramidal structures like ZnO nanoparticles. Did the authors simulate their TEM or STEM images to determine the shape of the particles? ,