Chemistry Reference
In-Depth Information
Notably, nanorods of zinc blende InP up to 100 nm long, with twin
boundaries and stacking faults, could also be prepared using an amendment
to the popular solution
V mate-
rials
46
using two single-source precursors, prepared
in situ
by dehalosilylation
chemistry.
47
To either a 2% DDA in TOA solution, or a 2% TOPO in TOP
solution containing InCl
3
and In(
t
Bu)
2
Cl, was added P(SiMe
3
)
3
followed by
a small amount of methanol to hydrolyse the P
-
liquid
-
solid route (SLS) to anisotropic III
-
d
n
1
y
4
n
g
|
3
Si bond, which was then
stirred at room temperature for a day. The reagents were then heated at
various temperatures and for various times, and isolated by precipitation
using methanol. The resulting rods were air sensitive, and the metal impu-
rities removed by addition of mercury to form alloys, which could also be
etched with HF. The use of the
in situ
formed [(
t
Bu)
2
InP(SiMe
3
)
2
]
2
allowed the
formation of metallic indium particles which catalysed the growth of the
rods, while [Cl
2
InP(SiMe
3
)
2
]
2
acted as the InP precursor. As the long-chain
amine capping agents bound strongly to indium, the seed particles prepared
were small, and the resulting rods therefore had diameters as small as 2.8 nm
with a length of up to 33 nm, with the small rods showing, in some cases
zigzag and tripod-type morphologies. In comparison, TOPO/TOP-capped
rods 5 nm in diameter of have been prepared under similar conditions.
The optical properties of quantum rods (2.8 nm
-
30 nm) were similar
in spectral position to 3 nm spherical InP dots, although the absorption
and emission spectra were notably broader, with a larger Stokes shi
10
-
of
ca.
400 meV.
InP rods, with average diameter of 4.2
39 nm have
also been grown by a similar SLS method with bismuth particles,
48
using
In(COOC
13
H
27
), HDA, TOP, TOPO and polydecene (and notably no phos-
phonic acid) into which was injected P(SiMe
3
)
3
at temperatures between
ca.
240 and 265
C. A
-
7.8 nm and length of 10
-
.
er a certain length of time, a stock solution of bismuth
particles in dioctyl adipate (DOA) was also injected into the reaction
ask, the
source of heat removed a
ed by
typical solvent/non-solvent interactions. The resulting rods were capped with
HDA and contained the bismuth seed, which could be removed by sonicating
a toluene solution of the rods with oleic acid for several hours, although this
also reduced the thickness of the structures. The rods exhibited two excitonic
features, with the onset of absorption at
ca.
1.5 eV (
ca.
825 nm), with no
detectable emission from the as-prepared rods. Etching the rods with HF
resulted in band edge emission with quantum yields of 0.16%, whereas
etched rods with the tips removed exhibited quantum yields of up to 0.6%.
These rods were used to determine the 3D
er 0.5
-
3 minutes and the product puri
wire transition which was
found to occur at 25 nm, and a more in-depth study exploring 2D and 3D
con
-
2D rod
-
erentiates between wire and dot behaviour, has also
been reported.
49
In this case, the rods were grown using the single-source
precursor [Me
2
InP(SiMe
3
)
2
]
2
, P(SiMe
3
)
3
in TOP using indium nanoparticles
as the seeds, although the use of bismuth particles as seed catalysts for SLS-
type growth of III
nement, which di
V materials has arguably become the most popular, and
has been extended to most materials.
50
-
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