Facile and Purification-Free Synthesis of Nitrogenated Amphiphilic

Feb 22, 2016 - +82-63-219-8158. Fax.: +82-63-219-8129. E-mail: [email protected] (S. ... iPSCs consisting of ITO/PEIE/PTB7:PC71BM (+ N-GCDs)/MoO3/Ag...
0 downloads 0 Views 1MB Size
Subscriber access provided by La Trobe University Library

Communication

Facile and purification-free synthesis of nitrogenated amphiphilic graphitic carbon dots Byung Joon Moon, Yelin Oh, Dong Heon Shin, Sang Jin Kim, Sanghyun Lee, Tae-Wook Kim, Min Park, and Sukang Bae Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.5b04915 • Publication Date (Web): 22 Feb 2016 Downloaded from http://pubs.acs.org on February 23, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Chemistry of Materials is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemistry of Materials

Facile and purification-free synthesis of nitrogenated amphiphilic graphitic carbon dots Byung Joon Moon,1† Yelin Oh,1† Dong Heon Shin,1 Sang Jin Kim,1 Sanghyun Lee,1,2 Tae-Wook Kim,1,2 Min Park1 and Sukang Bae1*

1

Soft Innovative Materials Research Center, Korea Institute of Science and Technology,

Eunha-ri san 101, Bongdong-eup, Wanju-gun, Jeollabukdo (or Jeonbuk) 565-905, Republic of Korea. 2

Department of Nano Material Engineering, Korea University of Science and Technology,

217 Gajeong-ro, Yuseong-gu, Daejeon 305-350, Republic of Korea



Corresponding author. Tel.: +82-63-219-8158; Fax.: +82-63-219-8129 E-mail address: [email protected] (S. Bae)



These authors contributed equally to this paper.

1 ACS Paragon Plus Environment

Chemistry of Materials

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract

The emerging carbon-based quantum dots have been attracting attention because of their tremendous potential for optoelectronic and biomedical applications, which is due to their unique and size-tunable optical properties, their ability to be functionalized, and their biocompatibility. Here, we report the facile one-step synthesis of highly fluorescent and amphiphilic n-doped graphitic carbon dots (N-GCDs) using a fumaronitrile (FN) precursor. An interesting property of the prepared GCDs is their near pH neutral dispersibility without refinement, which stands in contrast to reported methods. This finding indicates that our approach could lead to low-cost and efficient processability that is scalable and environmentally friendly. In addition, we find that our N-GCDs have high density of graphitic structure such as sp2-hybridized carbon and tiny amounts of defect by near-edge X-ray absorption fine structure (NEXAFS) results. Finally, to confirm the electro-optical behavior of N-GCDs on photovoltaic devices, we fabricate iPSCs consisting of ITO/PEIE/PTB7:PC71BM (+ N-GCDs)/MoO3/Ag. Using this effective approach, we demonstrate the highest conversion efficiency of ~8.6% resulting from improved photo-responsibility and charge transport based on various charge and energy transfer dynamics. Also, we believe that the shape, size and functionality of these GCDs can be controlled using other chemical species to provide a variety opportunities for use in optoelectronics, biological applications and sensors.

2 ACS Paragon Plus Environment

Page 2 of 28

Page 3 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Chemistry of Materials

INTRODUCTION Quantum dots (QDs), which are semiconductor nanocrystals with dimensions smaller than the exciton Bohr radius, show unique size effects and outstanding electronic, optical and electrochemical properties.1 Among these features is fluorescence, which is one of the most important properties of QDs. Over the past two decades, properties including high quantum yields, good photo-stability and resistance to photobleaching have led to QDs being utilized for light-emitting diodes (LEDs), biomedical imaging and biosensing.2-5 However, most of the high-performance QDs are composed of heavy metal elements (i.e., Cd, Pb and Hg), which limits QD applications due to their toxicity and potential environmental hazards. Recently, carbon-based fluorescent nanomaterials, especially carbon dots (CDs), graphene quantum dots (GQDs) and graphitic carbon dots (GCDs), have attracted much attention for its promising applications in opto-electronics, metal ion detection and biological research due to their low toxicity, unique spin property, robust chemical inertness, excellent biocompatibility and low cost.6-14 During the last decade, various methods have been developed to fabricate carbon based QDs that can be roughly classified into “top-down” and “bottom-up” approaches. “Top-down” approaches, which are based on reducing the size of large carbon materials, commonly involve complicated reactions or time-consuming purification processes.1518

Unlike “top-down” approaches, “bottom-up” methods, in particular pyrolysis

methods, are efficient synthetic routes that avoid several problems (e.g., carbonaceous aggregation, poor size control and uniformity, and unwanted surface properties) with relative ease and can produce carbon based QDs on a large scale.19-21 However, most of them that have been prepared via pyrolysis are mainly composed of sp3-hybridized carbon (low sp2/sp3 ratio) and possess substantial amounts of amorphous carbon structures. This is because of multiple factors that include 1) QDs being fabricated from non-graphitic and amorphous carbon sources (e.g., citric acid, glucose, L3 ACS Paragon Plus Environment

Chemistry of Materials

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

glutamic acid and urea),22-25 2) the dehydration process for converting C-C bonds (C atoms with sp3-hybridized orbitals) to C=C bonds (C atoms with sp2-hybridized orbitals) is not available via bottom-up approaches at short reaction times (~10 min) and low process temperatures