Mojgan Mazouchi

Bias-dependence of luminescent coupling efficiency in multijunction solar cells

In this work we describe the dependence of luminescent coupling efficiency on the bias-voltage in multijunction solar cells. We combine a theoretical derivation and Sentaurus simulations to show that the luminescent coupling efficiency has a significant dependence on the bias voltage, and such dependence is mainly due to the change in the ratio between radiative and non-radiative recombination currents at different bias voltage. We further show that such change is due to the variation in the recombination rate distribution in the cell. In addition to showing the necessity of including bias-dependence in luminescent coupling modeling, this work also demonstrates the importance of including a bias-dependent luminescent coupling efficiency to accurately model multijunction solar cells.

Enhanced optical properties due to indium incorporation in zinc oxide nanowires

Indium-doped zinc oxide nanowires grown by vapor-liquid-solid technique with 1.6 at. % indium content show intense room temperature photoluminescence (PL) that is red shifted to 20 meV from band edge. We report on a combination of nanowires and nanobelts-like structures with enhanced optical properties after indium doping. The near band edge emission shift gives an estimate for the carrier density as high as 5.5 × 1019 cm−3 for doped nanowires according to Motts critical density theory. Quenching of the visible green peak is seen for doped nanostructures indicating lesser oxygen vacancies and improved quality. PL and transmission electron microscopy measurements confirm indium doping into the ZnO lattice, whereas temperature dependent PL data give an estimation of the donor and acceptor binding energies that agrees well with indium doped nanowires. This provides a non-destructive technique to estimate doping for 1D structures as compared to the traditional FET approach. Furthermore, these indium doped na...

Submillimolar Detection of Adenosine Monophosphate Using Graphene-Based Electrochemical Aptasensor

In this paper, we present a successful demonstration of a graphene-based field-effect-transistor-like electrochemical nanobiosensor to accurately detect ultralow concentrations of adenosine monophosphate (AMP). Graphene being a two-dimensional material is a suitable option as a sensing element due to its biocompatibility and large surface area. It has also demonstrated surface binding chemistries as well as its ability to serve as a conducting channel. A short 20-base deoxyribonucleic acid (DNA) aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte. The sensor is found to be nonlinear in nature and sensitive in the picomolar (pM) and nanomolar (nM) concentrations of AMP. The linear region of operation is found to be 1 nM–100 μM and percentage change in drain current in this concentration region is calculated as

Quantization of acoustic-phonon shear modes in a nanowaveguide

{\text{1.56}}{\boldsymbol{\% }}/{\boldsymbol{decade}}

Luminescent coupling effects in double-junction solar cells

. A minimum concentration of 10 pM of AMP has been detected using this type of sensor.

The bias-dependence of luminescent coupling efficiency in multijunction solar cells

Acoustic energy trapping in a thin non-piezoelectric plate is studied. The confinement of resonant acoustic fields is described for the case where energy trapping is caused by thickening the center region of the plate. The elastic continuum mechanics model is used to determine the quantized acoustic-phonon modes in an isotropic nanowaveguide. The acoustic-phonon amplitudes and relative frequency dispersion relations are obtained analytically and presented for both the odd symmetry shear modes and even symmetry shear modes. The acoustic-phonon modes in the non-piezoelectric nanowaveguide are quantized. Furthermore, the limit of the quality factor and frequency (fQ) product achievable by a resonator is theoretically discussed and calculated in silicon resonators for three different orientations.

Growth and Characterization of Indium Oxide, Zinc Oxide and Cadmium Sulfide Nanowires by Vapor-Liquid-Solid Growth Technique

We presented an analytical model which predicts a voltage enhancement in photocurrent-matched double-junction cells due to luminescent coupling between the two junctions. We demonstrated that the voltage increase between VMPP to VOC can be computed in terms of the luminescent coupling efficiency. Then we examined the model by simulation of a double-junction cell under different luminescent coupling efficiencies. We demonstrated that the upper limit of voltage enhancement in a double-junction cell between VMPP to VOC is 17.8 mV. The results demonstrate that the voltage enhancement increases with increasing the luminescent coupling efficiency, which consequently enhance the cell efficiency.

Quantized acoustic-phonon shear horizontal modes in an unbounded hexagonal nitride-based piezoelectric nanostructure

In this work we describe the dependence of luminescent coupling efficiency on the bias-voltage in multijunction solar cells. We combine a theoretical derivation and Sentaurus simulations to show that the luminescent coupling efficiency has a significant dependence on the bias voltage, and such dependence is mainly due to the change in the ratio between radiative and non-radiative recombination currents at different bias voltage. We further show that such change is due to the variation in the recombination rate distribution in the cell. In addition to showing the necessity of including bias-dependence in luminescent coupling modeling, this work also demonstrates the importance of including a bias-dependent luminescent coupling efficiency to accurately model multijunction solar cells.