All entries for jing kong

Jing Kong

Title: Associate Professor
Department: Department of Electrical Engineering and Computer Science

Collaborators

M. Dresselhaus, EECS, MIT
A. Chandrakasan, EECS, MIT
T. Palacios, EECS, MIT
V. Bulovic, EECS, MIT
P. Jarrillo-Herrero, Physics, MIT
M. Strano, ChemE, MIT
K. Gleason, ChemE, MIT
J. Zhang and Z.F.Liu, Chemistry, Peking University

Postdoctoral Associates

S. M. Jung
Y. H. Lee
C. T. Lin
H. S. Park
D. L. Mafra

Graduate Students

A. L. Hsu, Res. Asst., EECS
Y. C. Shin, Res. Asst., DMSE
W. J. Fang, Res. Asst., EECS
Y. Song, Res. Asst., EECS

Research Staff

T. Y. Zeng, Research Scientist

Support Staff

L. von Bosau, Admin. Asst. I

Publications

Fang, Wenjing; Hsu, Allen L; Caudillo, Roman; Song, Yi; Birdwell, A Glen; Zakar, Eugene; Kalbac, Martin; Dubey, Madan; Palacios, Tomas; Dresselhaus, Millie S; Araujo, Paulo T; Kong, Jing, ” Rapid identification of stacking orientation in isotopically labeled chemical-vapor grown bilayer graphene by Raman spectroscopy”, Nano letters: pp1541-8, 2013.

Lee, Yi-Hsien; Yu, Lili; Wang, Han; Fang, Wenjing; Ling, Xi; Shi, Yumeng; Lin, Cheng-Te; Huang, Jing-Kai; Chang, Mu-Tung; Chang, Chia-Seng; Dresselhaus, Mildred; Palacios, Tomas; Li, Lain-Jong; Kong, Jing, ” Synthesis and transfer of single-layer transition metal disulfides on diverse surfaces”, Nano letters, 13, pp 1852-7, 2013.

Park, Hyesung; Chang, Sehoon; Smith, Matthew; Gradecak, Silvija; Kong, Jing,” Interface engineering of graphene for universal applications as both anode and cathode in organic photovoltaics”, Scientific Reports Vol.3, 1581, 2013.

Kim, Soo Min; Hsu, Allen; Araujo, P. T.; Lee, Yi-Hsien; Palacios, Tomas; Dresselhaus, Mildred; Idrobo, Juan-Carlos; Kim, Ki Kang; Kong, Jing,” Synthesis of Patched or Stacked Graphene and hBN Flakes: A Route to Hybrid Structure Discovery”, Nano Letters. 13 pp 933-941, 2013.

Park, Hyesung; Chang, Sehoon; Jean, Joel; Cheng, Jayce J; Araujo, Paulo T; Wang, Mingsheng; Bawendi, Moungi G; Dresselhaus, Mildred S; Bulovic, Vladimir; Kong, Jing; Gradecak, Silvija, “Graphene Cathode-Based ZnO Nanowire Hybrid Solar Cells”, Nano Letters, 13 pp233-239, 2013.

Jung, Sung Mi; Jung, Hyun Young; Dresselhaus, Mildred S.; Jung, Yung Joon; Kong, Jing, ” A facile route for 3D aerogels from nanostructured 1D and 2D materials”, Scientific Reports Vol 2, Article Number: 849,2012.

Hempel, Marek; Nezich, Daniel; Kong, Jing; Hofmann, Mario, ” A Novel Class of Strain Gauges Based on Layered Percolative Films of 2D Materials”, Nano Letters,12 pp5714-5718, 2012.

Kim, Ki Kang; Hsu, Allen; Jia, Xiaoting; Kim, Soo Min; Shi, Yumeng; Dresselhaus, Mildred; Palacios, Tomas; Kong, Jing, ” Synthesis and Characterization of Hexagonal Boron Nitride Film as a Dielectric Layer for Graphene Devices”, ACS NANO Vol 6, pp 8583-8590, 2012.

Hofmann, Mario; Shin, Yong Cheol; Hsieh, Ya-Ping; Dresselhaus, Mildred S.; Kong, Jing, ” A facile tool for the characterization of two-dimensional materials grown by chemical vapor deposition”, Nano Research Vol 5 pp504-511, 2012.

Park, Hyesung; Howden, Rachel M; Barr, Miles C; Bulovic, Vladimir; Gleason, Karen; Kong, Jing, “Organic Solar Cells with Graphene Electrodes and Vapor Printed Poly(3,4-ethylenedioxythiophene) as the Hole Transporting Layers” ACS nano Vol 6, pp6370-7, 2012

Shi, Yumeng; Zhou, Wu; Lu, Ang-Yu; Fang, Wenjing; Lee, Yi-Hsien; Hsu, Allen Long; Kim, Soo Min; Kim, Ki Kang; Yang, Hui Ying; Li, Lain-Jong; Idrobo, Juan-Carlos; Kong, Jing “van der Waals Epitaxy of MoS2 Layers Using Graphene As Growth Templates”, Nano Letters. Vol 12 pp2784-2791,2012.

Interface Engineering of Graphene for Universal Applications as Both Anode and Cathode in Organic Photovoltaics

Authors: H. Park, S. Chang, M. Smith, S. Gradečak, J. Kong
Sponsorship: Eni S.p.A

The high transparency of graphene^[1], together with its good electrical conductivity^[2] and mechanical robustness^[3], enable its use as transparent electrodes in optoelectronic devices such as solar cells. While initial demonstrations of graphene-based organic photovoltaics (OPV) have been promising, realization of scalable technologies remains challenging due to their performance and, critically, their poor device reproducibility and yield. In this work, by engineering the interface between graphene and organic layers, we demonstrate that device performance and yield become close to that of devices using indium tin oxide. Our study confirms that the key issue leading to the poor performance or irreproducibility in graphene-based OPV originates from the graphene interface and can be addressed by a simple interface modification method introduced in this work. This interface modification is achieved by inserting a thin polymeric buffer layer between the pristine graphene surface and the PEDOT:PSS hole injection layer (HIL), thus forming a double-HIL structure (D-HIL) (Figure 1). We also demonstrate that this method can be further expanded to the inverted solar cell geometry, using TiO_x or ZnO as the electron-transporting and hole-blocking layer, where graphene is utilized as the cathode, thus illustrating the broad application of graphene as a transparent conductor in OPV in general (Figure 2). By engineering the interfacial HIL between the graphene electrode and the organic donor layer, we find that the performance and yield of graphene-based OPV devices become close to those of devices using ITO electrodes. This work takes one step forward in the realization of graphene as a viable replacement for or alternative to ITO for various optoelectronic device applications.

: Figure 1: Composition and device performance of typical organic solar cells using graphene anodes. (a) Schematic diagram of the graphene anode OPV architecture: graphene/PEDOT:PEG(PC), 40nm/PEDOT:PSS, 20nm/DBP, 25nm/C60, 40nm/BCP, 8.5nm/Al, 100nm. (b) Cross-sectional TEM image (left) of the complete device described in (a), with an energy dispersive EDS elemental line scan overlaid on a schematic of the device cross-section (right). (c) Flat-band energy level diagram of the completed OPV device. (d) Current density vs. voltage (J-V) characteristics of a representative graphene device (using D-HIL, black) compared with ITO reference cells (red and blue) under simulated AM 1.5G illumination at 100 mW∙cm-2, illustrating comparable performances.

: Figure 2: J-V characteristics of inverted small molecule solar cells with TiOx ESL. (a) On D-HIL modified graphene and (b) on ITO under AM 1.5G at 100 mW∙cm-2. Device performances with normal geometry are shown for comparison. J-V characteristics of representative graphene and ITO devices with ZnO ESL. Using (c) small molecule photoactive layers and (d) P3HT:PCBM photoactive layer under AM 1.5G at 100 mW∙cm-2.

R. Nair, P. Blake, A. Grigorenko, K. Novoselov, T. Booth, T. Stauber, N. Peres, and A. Geim “Fine structure constant defines visual transparency of graphene,” Science, vol. 320, no. 5881, pp. 1308-1308, 2008. [↩]
K. Bolotin, K. Sikes, Z. Jiang, M. Klima, G. Fudenberg, J. Hone, P. Kim, and H. Stormer, “Ultrahigh electron mobility in suspended graphene,” Solid State Commun., vol. 146, no. 9-10, pp. 351-355, 2008. [↩]
J. Bunch, A. van der Zande, S. Verbridge, I. Frank, D. Tanenbaum, J. Parpia, H. Craighead, and P. McEuen, “Electromechanical resonators from graphene sheets,” Science, vol. 315, no. 5811, pp. 490-493, 2007. [↩]

Rapid Identification of Stacking Orientation in Isotopically Labeled Chemical-vapor Grown Bilayer Graphene by Raman Spectroscopy

Authors: W. Fang, A. L. Hsu, R. Caudillo (Intel), Y. Song, A. G. Birdwell (U.S. Army Research Laboratory), E. Zakar (U.S. Army Research Laboratory), M. Kalbac, M. Dubey (U.S. Army Research Laboratory), T. Palacios, M. S. Dresselhaus, P. T. Araujo J. Kong
Sponsorship: Intel Corporation, U.S. Army Research Laboratory

Figure 1: Raman spectroscopy and TEM characterization of bilayer graphene. (a) Two representative Raman spectra taken from suspended bilayer graphene on a SiN TEM grid. The insets show the stacking orientation. (b) The SAED patterns for (a) and the corresponding intensities profile along the yellow lines. Inset in upper-left corner of (b) is TEM image, which indicates the number of layers.

The growth of large-area bilayer graphene has been of technological importance for graphene electronics. The successful application of graphene bilayers critically relies on the precise control of the stacking orientation, which determines both electronic and vibrational properties of the bilayer system. Toward this goal, an effective characterization method is critically needed to allow researchers to easily distinguish the bilayer stacking orientation (i.e., AB stacked or turbostratic). In this work, we developed such a method to provide facile identification of the stacking orientation by isotope labeling. Raman spectroscopy of these isotopically-labeled bilayer samples shows a clear signature associated with AB stacking between layers, enabling rapid differentiation between turbostratic and AB-stacked bilayer regions. Using this method, we were able to characterize the stacking orientation in bilayer graphene grown through low-pressure chemical vapor deposition (LPCVD) with enclosed Cu foils, achieving almost 70% AB-stacked bilayer graphene. Furthermore, by combining surface sensitive fluorination with such hybrid ¹²C/¹³C bilayer samples, we are able to identify that the second layer grows underneath the first-grown layer, which is similar to a recently reported observation.

MTL Annual Research Report 2013