Electronic Supplementary Information for:
Efficient one-pot synthesis of monodisperse
alkyl-terminated colloidal germanium
nanocrystals
Darragh Carolan* and Hugh Doyle
Tyndall National Institute, University College Cork, Lee Maltings, Cork, Ireland.
* Email: darragh.carolan@tyndall.ie
Email: hugh.doyle@tyndall.ie
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Figures
Fig. ESM1 TEM images and size histograms and of Ge NCs produced by the reduction of a single
precursor (a) n-butyltrichlorogermane and (b) GeCl4
Fig. ESM2 FTIR of the butyl capped Ge NCs produced by reduction of both germanium
precursors
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Fig. ESM3 XPS spectra of the butyl capped Ge NCs produced by reduction of both germanium
precursors
Fig. ESM4 UV-Vis, PL and PLE spectra for Ge NCs produced by the reduction of a single
precursor (a) n-butyltrichlorogermane and (b) GeCl4
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Determination of the quantum yield
The quantum yield of the Ge NCs was determined using the established literature
method (Williams et al. 1983). All glassware was thoroughly washed with
acetone, methanol, DI water and rinsed with the solvent used in the
measurements. Solutions were prepared with optical densities between 0.01-0.1 to
minimise the “inner filter” (self-quenching) effects. Quantum yields were
determined by comparison of the integrated fluorescence intensities of the Ge
NCs
in
chloroform
with
solutions
of
the
reference
emitter
9,10-
diphenylanthracene in cyclohexane. The quantum yields were calculated using the
formula
𝑄𝑌𝑆 = 𝑄𝑌𝑅 ×
𝑚𝑆
𝑛𝑆
×
𝑚𝑅 𝑛𝑅
Where 𝑄𝑌𝑆 is the quantum yield of the sample, 𝑄𝑌𝑅 is the quantum yield of the
reference emitter (9,10-diphenylanthracene), 𝑚𝑆 and 𝑚𝑅 are the slopes of the
linear fits to plots of the integrated intensity vs absorbance of the sample and
reference emitter, while 𝑛𝑆 and 𝑛𝑅 are the refractive indices of the sample solvent
and the reference solvent, respectively.
PL spectra of the Ge NCs and the reference emitter were acquired using an
excitation wavelength of 340 nm and integrated from 360-500 nm, see Figure
ESM5(a). This was repeated for various solutions with different concentrations,
and the integrated fluorescence intensity plotted against the solution absorbance,
see Figure ESM5(b). The slopes (𝑚𝑆 and 𝑚𝑅 ) were determined using a linear
least squares fitting with a correlation coefficient of (R2 ≥ 0.99).
Fig. ESM5 (a) The fluorescence spectrum of 9,10 diphenylanthracene showing absorbance value,
integration range and integrated intensity. (b) Plot of integrated intensity vs absorbance for various
dilutions of the reference material with a linear fit to the data
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References
Williams ATR, Winfield SA, Miller JN (1983) Relative fluorescence quantum
yields using a computer-controlled luminescence spectrometer. Analyst
108:1067-1071 doi:10.1039/an9830801067
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