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Solution-processed 2-dimensional hole-doped ionic graphene compounds

delete2017-01-01
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PRE
AI
F
Fong-Yu Kam
R
Rui‐Qi Png
M
Mervin Chun‐Yi Ang
P
Pawan Kumar
K
Km Rubi
R
R. Mahendiran
O
Olga Solomeshch
N
Nir Tessler
G
Geok-Kieng Lim
L
Lay‐Lay Chua *
P
Peter K. H. Ho *
DOI:10.1039/c7mh00068edelete
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Abstract

Abstract

En 中文
Contacts with suitable work functions are important not only for ohmic injection of carriers but also to set up the built-in potential required for various semiconductor processes including current rectification, light emission and photovoltaic generation. For two-dimensional (2D) materials, one way to shift the work function is by intercalation doping with suitable donors or acceptors. Here, using an atomic sheet transfer methodology, we report layer-by-layer assembly of centimeter-square sizes of graphene-fluorofullerene multilayers through directed stacking of chemical-vapor-deposited (CVD) graphene sheets and self-assembly of fluorofullerene acceptors, for example C60F48, to give a 1 eV increase in work function to 5.7 eV, which is unprecedented for a well-defined compound. These assemblies exhibit an unusual motif of fully-ionized large dopants in open packing with the graphene sheets. As a consequence, they show a sizeable electrostatic dipole to give ultrahigh work function at acceptor-terminated surfaces even for a moderate hole doping level of 1.6 X 10(13) cm(-2) per sheet. They exhibit little additional carrier scattering and a remarkable chemical stability. Hall measurements reveal unity doping efficiency with temperature-independent hole density, mobility and electrical conductivity down to 2.5 K, which are atypical of conventional graphite intercalation compounds. These materials provide the first examples of a novel domain of doped 2D assemblies where large ions are incorporated through room-temperature solution processing, which opens new opportunities beyond van der Waals semiconductor heterostructures.
Keywords:
GRAPHITE-INTERCALATION COMPOUNDS
ELECTRONIC-STRUCTURE
WORK-FUNCTION
TRANSPARENT ELECTRODES
LAYER GRAPHENE
OHMIC CONTACTS
SEMICONDUCTORS
C-60
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Journal

Materials Horizons cover
Materials Horizons
IF:
10.7
Papers:
3.6K
Citations:
2.4W

Organization

T
Technion Israel Institute of Technology
Scholars:
1.6W
Papers: 1.5W
Citations: 2.0W
N
National University of Singapore
Scholars:
7.5W
Papers: 6.4W
Citations: 11.4W