A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots

Kortschot, R. J.; Bakelaar, I. A.; Erné, Ben H.; Kuipers, Martijn

doi:10.1063/1.4867666

Cited by 8 publications

(10 citation statements)

References 21 publications

(30 reference statements)

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“…Dielectric spectra were recorded with a differential complex permittivity setup. 30 The setup was not used in its differential mode, but the voltage was measured over a measurement resistor in series with the capacitor directly. Measurements were performed upon applying a voltage of 25 mV in the frequency range of 10 −1 to 10 6 Hz at a temperature of either 293 or 295 K. It was verified that the response was independent of the applied voltage; deviations were only observed at a voltage of ≥1 V, and in that case only at the lowest frequencies (<1 Hz).…”

Section: Experimental Methodsmentioning

confidence: 99%

Debye Length Dependence of the Anomalous Dynamics of Ionic Double Layers in a Parallel Plate Capacitor

2014

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The electrical impedance spectrum of simple ionic solutions is measured in a parallel plate capacitor at small applied ac voltage. The influence of the ionic strength is investigated using several electrolytes at different concentrations in solvents of different dielectric constants. The electric double layers that appear at the electrodes at low frequencies are not perfectly capacitive. At moderate ionic strength, ion transport agrees with a model based on the Poisson–Nernst–Planck (PNP) equations. At low ionic strength, double layer dynamics deviate from the PNP model, and the deviation is well described by an empirical function with only one fit parameter. This deviation from the PNP equations increases systematically with increasing Debye length, possibly caused by the long-range Coulomb interaction.

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Section: Experimental Methodsmentioning

confidence: 99%

Debye Length Dependence of the Anomalous Dynamics of Ionic Double Layers in a Parallel Plate Capacitor

2014

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“…Dielectric spectra (ε ex = ε ex ′ – iε ex ″) were measured using the differential complex permittivity setup and measurement procedures described in ref , with the use of the gold/ITO capacitor with cell constant K c = 28.70 pF and electrode spacing d = 94.6 μm. The capacitor was filled with dispersion in a glovebox under a nitrogen atmosphere.…”

Section: Experimental Methodsmentioning

confidence: 99%

Equilibrium Structures of PbSe and CdSe Colloidal Quantum Dots Detected by Dielectric Spectroscopy

et al. 2014

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The permanent electrical dipole moment of colloidal quantum dots is important for their optoelectronic properties and can be determined by dielectric spectroscopy. Until now, however, colloidal interactions have not been taken into account in the interpretation of the spectra. Here, dielectric spectra of PbSe and CdSe colloidal quantum dots dispersed in an apolar liquid are measured from 1 Hz to 10 MHz. At frequencies of 10 kHz−1 MHz, Brownian rotation of nanoparticles with a permanent electric dipole moment is detected. At the lowest concentrations (∼0.1 vol %), the nanoparticles rotate independently of each other, and their dipole moment, for both PbSe and CdSe, is on the order of 40−50 D. At higher concentrations (≥0.3 vol %), the dipolar relaxation becomes slower, indicating the presence of nanoparticle structures. A simple model is used to estimate the interaction strength, which appears to be stronger than expected from the weak dipole moment, and has possibly also contributions from electrical moments of higher order. Our results indicate that nanoparticle interactions in liquid media lead to small equilibrium structures that affect dielectric measurements of the dipole moment already at concentrations of a few tenths of a volume percent.

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“…In practice, there are several issues to be tackled in order to avoid undesirable effects such as, the electrical double layer (EDL), and parasitic capacitance and inductance [7]. This, requires the design of adequate measurement electrodes [8], or sophisticated instrumentation [9].…”

Section: Introductionmentioning

confidence: 99%

Sensing Micro-colloid Concentration by Spectral Impedance Measurements and Relaxation Times Analysis

Ramírez-Chavarría

Sánchez‐Pérez

2019

2019 IEEE Sensors Applications Symposium (SAS)

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This paper presents an attractive method towards sensing and quantifying the concentration of dielectric particles suspended in a highly conductive medium. Fast electrical impedance spectroscopy (EIS) measurements were performed, based on an electrochemical setup and a non-parametric unbiased estimator. The impedance data are then mapped from the frequency domain to a time constant domain via the distribution of relaxation times (DRT) model. It is shown that application of DRT can systematically give a distribution function which is directly related with the concentration of micro-colloid samples. As a result, the samples were characterized with high sensitivity and resolution.

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A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots

Cited by 8 publications

References 21 publications

Debye Length Dependence of the Anomalous Dynamics of Ionic Double Layers in a Parallel Plate Capacitor

Debye Length Dependence of the Anomalous Dynamics of Ionic Double Layers in a Parallel Plate Capacitor

Equilibrium Structures of PbSe and CdSe Colloidal Quantum Dots Detected by Dielectric Spectroscopy

Sensing Micro-colloid Concentration by Spectral Impedance Measurements and Relaxation Times Analysis

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