scholarly journals Light Management in Single Rectangular Silicon Nanowires for Photovoltaic Applications

2020 ◽  
Author(s):  
Wenfu Liu
Keyword(s):  
Cross Section ◽  
Silicon Nanowires ◽  
High Efficiency ◽  
Light Harvesting ◽  
Rectangular Cross Section ◽  
Light Illumination ◽  
Vertical Side ◽  
Photovoltaic Applications ◽  
Light Management ◽  
Horizontal Side

Light management in single nanowires (NWs) is of great importance for photovoltaic applications. However, square NWs (SNWs) can limit their light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light management in single silicon NWs with a rectangular cross-section (RNWs). We demonstrate that the RNWs exhibit significantly enhanced light-harvesting compared with the SNWs, which can be attributed to the symmetry-broken structure that can orthogonalize the direction of light illumination and the leaky mode resonances (LMRs). That is, the rectangular cross-section can simultaneously increase the light path length by increasing the vertical side and reshape the LMR modes by decreasing the horizontal side. We found that the light absorption can be engineered via tuning the horizontal and vertical sides, the photocurrent is significantly enhanced by 276.5% or 82.9% in comparison with that of the SNWs with the same side length as the horizontal side of 100 nm or the vertical side of 1000 nm, respectively. This work advances our understanding of how to improve light-harvesting based on the symmetry breaking from the SNWs to RNWs and provides an effective way for designing high-efficiency single NW photovoltaic devices.

scholarly journals Improving Absorption in Single Silicon Nanowires by Symmetry-breaking Design from Square to Rectangular Cross-section

2021 ◽  
Author(s):  
Wenfu Liu
Keyword(s):  
Symmetry Breaking ◽  
Silicon Nanowires ◽  
Light Absorption ◽  
High Efficiency ◽  
Rectangular Cross Section ◽  
Photovoltaic Devices ◽  
Vertical Side ◽  
Photovoltaic Applications ◽  
Single Nanowires ◽  
Horizontal Side

Light absorption in single nanowires (NWs) is one of the most crucial factors for photovoltaic applications. In this paper, we carried out a detailed investigation of light absorption in single rectangular NWs (RNWs). We show that the RNWs exhibit improved light absorption compared with the square NWs (SNWs), which can be attributed to the symmetry-breaking structure that can increase the light path length by increasing the vertical side and the enhanced leaky mode resonances (LMRs) by decreasing the horizontal side. We found that the light absorption in silicon RNWs can be enhanced by engineering the horizontal and vertical sides, the photocurrent is significantly increased by 276.5% or 82.9% compared with that of the SNWs with the same side length as the horizontal side of 100 nm or the vertical side of 1000 nm, respectively. This work provides an effective way for designing high-efficiency single NW photovoltaic devices based on the symmetry breaking from the SNWs to RNWs.

scholarly journals Enhanced Light-Harvesting in Single Rectangular Silicon Nanowires

2021 ◽  
Vol 16 (3) ◽  
pp. 428-433
Author(s):  
Wenfu Liu ◽  
Xin Lio ◽  
Yinling Wang ◽  
Bin Wen
Keyword(s):  
Solar Cells ◽  
Silicon Nanowires ◽  
Light Harvesting ◽  
Numerical Results ◽  
Leaky Mode ◽  
Light Path ◽  
Vertical Side ◽  
Single Nanowires ◽  
Horizontal Side

Light-harvesting of single nanowires is very crucial to enhance conversion efficency of solar cells. Here, we systematically examined light-harvesting of single rectangular nanowires and found that light-harvesting of rectangular nanowires is increased contrasted with that of square nanowires, which is because decreasing the horizontal side can strengthen the leaky mode resonances and increasing the vertical side can increase the length of the light path. Numerical results showed that the photocurrent of single rectangular silicon nanowires is dramatically enhanced by 82.9% or 276.5% in comparison with that of square nanowires with the same vertical side (1000 nm) or horizontal side (100 nm), respectively. This work indicates that light-harvesting of single nanowires can be improved by decreasing the symmetry from the square to rectangular nanowires.

scholarly journals Light Trapping in Single Elliptical Nanowires

2020 ◽  
Author(s):  
Wenfu Liu ◽  
Yinling Wang ◽  
Xiaolei Guo ◽  
Jun Song ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Cross Section ◽  
High Efficiency ◽  
Light Trapping ◽  
Vertical Axis ◽  
Horizontal Axis ◽  
Elliptical Cross Section ◽  
Light Illumination ◽  
Elliptical Cross ◽  
Photovoltaic Applications ◽  
Single Nanowires

Light trapping in single nanowires (NWs) are of vital importance for photovoltaic applications. However, circular NWs (CNWs) can limit its light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light trapping in single NWs with an elliptical cross-section (ENWs). We demonstrate that the ENWs exhibit significantly enhanced light trapping compared with the CNWs, which can be ascribed to the symmetry-broken structure that can orthogonalize the direction of light illumination and the leaky mode resonances (LMRs). That is, the elliptical cross-section can simultaneously increase the light path length by increasing the vertical axis and reshape the LMR modes by decreasing the horizontal axis. We found that the light absorption can be engineered via tuning the horizontal and vertical axes, the photocurrent is significantly enhanced by 374.0% (150.3%, 74.1%) or 146.1% (61.0%, 35.3%) in comparison with that of the CNWs with the same diameter as the horizontal axis of 100 (200, 400) nm or the vertical axis of 1000 nm, respectively. This work advances our understanding of how to improve light trapping based on the symmetry breaking from the CNWs to ENWs and provides a rational way for designing high-efficiency single or self-assembled NW photovoltaic devices.

scholarly journals Light Trapping in Single Elliptical Silicon Nanowires

2020 ◽  
Author(s):  
Wenfu Liu ◽  
Yinling Wang ◽  
Xiaolei Guo ◽  
Jun Song ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Cross Section ◽  
Silicon Nanowires ◽  
High Efficiency ◽  
Light Trapping ◽  
Vertical Axis ◽  
Horizontal Axis ◽  
Elliptical Cross Section ◽  
Light Illumination ◽  
Elliptical Cross ◽  
Single Nanowires

Light trapping in single nanowires (NWs) are of vital importance for photovoltaic applications. However, circular NWs (CNWs) can limit its light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light trapping in single NWs with an elliptical cross-section (ENWs). We demonstrate that the ENWs exhibit significantly enhanced light trapping compared with the CNWs, which can be ascribed to the symmetry-broken structure that can orthogonalize the direction of light illumination and the leaky mode resonances (LMRs). That is, the elliptical cross-section can simultaneously increase the light path length by increasing the vertical axis and reshape the LMR modes by decreasing the horizontal axis. We found that the light absorption can be engineered via tuning the horizontal and vertical axes, the photocurrent is significantly enhanced by 374.0% (150.3%, 74.1%) or 146.1% (61.0%, 35.3%) in comparison with that of the CNWs with the same diameter as the horizontal axis of 100 (200, 400) nm or the vertical axis of 1000 nm, respectively. This work advances our understanding of how to improve light trapping based on the symmetry breaking from the CNWs to ENWs and provides a rational way for designing high-efficiency single or self-assembled NW photovoltaic devices.

scholarly journals Light Trapping in Single Elliptical Silicon Nanowires

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2121
Author(s):  
Wenfu Liu ◽  
Yinling Wang ◽  
Xiaolei Guo ◽  
Jun Song ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Cross Section ◽  
Silicon Nanowires ◽  
High Efficiency ◽  
Light Trapping ◽  
Vertical Axis ◽  
Horizontal Axis ◽  
Elliptical Cross Section ◽  
Light Illumination ◽  
Elliptical Cross ◽  
Single Nanowires

Light trapping in single nanowires (NWs) is of vital importance for photovoltaic applications. However, circular NWs (CNWs) can limit their light-trapping ability due to high geometrical symmetry. In this work, we present a detailed study of light trapping in single silicon NWs with an elliptical cross-section (ENWs). We demonstrate that the ENWs exhibit significantly enhanced light trapping compared with the CNWs, which can be ascribed to the symmetry-broken structure that can orthogonalize the direction of light illumination and the leaky mode resonances (LMRs). That is, the elliptical cross-section can simultaneously increase the light path length by increasing the vertical axis and reshape the LMR modes by decreasing the horizontal axis. We found that the light absorption can be engineered via tuning the horizontal and vertical axes, the photocurrent is significantly enhanced by 374.0% (150.3%, 74.1%) or 146.1% (61.0%, 35.3%) in comparison with that of the CNWs with the same diameter as the horizontal axis of 100 (200, 400) nm or the vertical axis of 1000 nm, respectively. This work advances our understanding of how to improve light trapping based on the symmetry breaking from the CNWs to ENWs and provides a rational way for designing high-efficiency single NW photovoltaic devices.

scholarly journals High-Throughput, Label-Free Isolation of White Blood Cells From Whole Blood Using Parallel Spiral Microchannels With U-Shaped Cross-Section

2021 ◽  
Author(s):  
Amirhossein Mehran ◽  
Peyman Rostami ◽  
Mohammad Said Saidi ◽  
Bahar Firoozabadi ◽  
Navid Kashaninejad
Keyword(s):  
Cross Section ◽  
High Throughput ◽  
Whole Blood ◽  
Blood Cells ◽  
High Efficiency ◽  
Rectangular Cross Section ◽  
White Blood Cells ◽  
Label Free ◽  
Entire Cross Section ◽  
Shaped Cross Section

Rapid isolation of white blood cells (WBCs) from whole blood is an essential part of any WBC examination platform. However, most conventional cell separation techniques are labor-intensive and low throughput, require large volumes of samples, need extensive cell manipulation, and have low purity. To address these challenges, we report the design and fabrication of a passive, label-free microfluidic device with a unique U-shaped cross-section to separate WBCs from whole blood using hydrodynamic forces that exist in a microchannel with curvilinear geometry. It is shown that the spiral microchannel with a U-shaped cross-section concentrates larger blood cells (e.g., WBCs) in the inner cross-section of the microchannel by moving smaller blood cells (e.g., red blood cells (RBCs) and platelets) to the outer microchannel section and preventing them from returning to the inner microchannel section. Therefore, it overcomes the major limitation of a rectangular cross-section where secondary Dean vortices constantly enforce particles throughout the entire cross-section and decrease its isolation efficiency. Under optimal settings, more than 95% of WBCs can be isolated from whole blood under high-throughput (6 ml/min), high-purity (88%), and high-capacity (180 ml of sample in 1 hour) conditions. High efficiency, fast processing time, and non-invasive WBC isolation from large blood samples without centrifugation, RBC lysis, cell biomarkers, and chemical pre-treatments make this method an ideal choice for downstream cell study platforms.

The Method of Point Electric Moments in the Problem of Calculating Disturbed Electric Fields

2020 ◽  
Vol 63 (5) ◽  
pp. 17-22
Author(s):  
Sergey Basan ◽  
◽  
Yury Bachvalov ◽  
Julia Yufanova ◽  
◽  
...  
Keyword(s):  
Cross Section ◽  
Electric Fields ◽  
High Efficiency ◽  
Rectangular Cross Section ◽  
Point Sources ◽  
Uniform Field ◽  
Numerical Instability ◽  
Urgent Problem ◽  
Distributed Parameters ◽  
The Difference

The article is devoted to solving the urgent problem of increasing the efficiency of methods for calculating the electric field. A meshless method for calculating disturbed stationary electric fields is proposed, based on the use of point electric moments. In this case, the accuracy of the calculation of the potential increases and the numerical instability caused by the error in the difference between close values when calculating the potential of the dipole is excluded. Replacing sources with distributed parameters is performed by a set of point sources. This makes it possible to exclude the operations of integration over the volume and surface, replacing them by summing the contributions of the moments. The absence of a grid significantly reduces the total number of un-knowns. The application of the method is shown by examples. The electric fields disturbed by the introduction of a dielectric cylinder, a conducting cylinder and a conducting rod of rectangular cross-section into a uniform field are calculated. The results obtained show the high efficiency of the developed method.

A Simple Unified Treatment of the Torsion Problem in Bars of Rectangular Cross-Section and Levy's Solution in Classical Plate Theory

1996 ◽  
Vol 24 (1) ◽  
pp. 87-91
Author(s):  
Patricio A. A. Laura ◽  
Roberto Gelos
Keyword(s):  
Coordinate System ◽  
Cross Section ◽  
Plate Theory ◽  
Rectangular Cross Section ◽  
Torsion Problem ◽  
Unified Approach ◽  
Classical Plate Theory ◽  
Vertical Side ◽  
First Case ◽  
Axis Of Symmetry

A survey of the literature reveals that the problems stated in the title are solved independently: in the case of the torsion problem the trigonometric terms are of the type ( cos (nπx)/2a, n = 1,3,5,…) while when implementing Levy's solution one uses terms of the type ( sin (nπx)/a, n = 1,3,5,…). In the first case the coordinate system coincides with the axis of symmetry of the rectangle while, in the second, the y-axis coincides with the left, vertical side of the rectangle and the x-axis is the horizontal axis of symmetry of the configuration. It is shown in the present study that a basic, unified approach is possible for solving both problems using the coordinate system mentioned in the second place and expressing the dependent variable in terms of the infinite series [Formula: see text]

scholarly journals High-Throughput, Label-Free Isolation of White Blood Cells from Whole Blood Using Parallel Spiral Microchannels with U-Shaped Cross-Section

Biosensors ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 406
Author(s):  
Amirhossein Mehran ◽  
Peyman Rostami ◽  
Mohammad Said Saidi ◽  
Bahar Firoozabadi ◽  
Navid Kashaninejad
Keyword(s):  
Cross Section ◽  
High Throughput ◽  
Whole Blood ◽  
Blood Cells ◽  
High Efficiency ◽  
Rectangular Cross Section ◽  
White Blood Cells ◽  
Label Free ◽  
Entire Cross Section ◽  
Shaped Cross Section

Rapid isolation of white blood cells (WBCs) from whole blood is an essential part of any WBC examination platform. However, most conventional cell separation techniques are labor-intensive and low throughput, require large volumes of samples, need extensive cell manipulation, and have low purity. To address these challenges, we report the design and fabrication of a passive, label-free microfluidic device with a unique U-shaped cross-section to separate WBCs from whole blood using hydrodynamic forces that exist in a microchannel with curvilinear geometry. It is shown that the spiral microchannel with a U-shaped cross-section concentrates larger blood cells (e.g., WBCs) in the inner cross-section of the microchannel by moving smaller blood cells (e.g., RBCs and platelets) to the outer microchannel section and preventing them from returning to the inner microchannel section. Therefore, it overcomes the major limitation of a rectangular cross-section where secondary Dean vortices constantly enforce particles throughout the entire cross-section and decrease its isolation efficiency. Under optimal settings, we managed to isolate more than 95% of WBCs from whole blood under high-throughput (6 mL/min), high-purity (88%), and high-capacity (360 mL of sample in 1 h) conditions. High efficiency, fast processing time, and non-invasive WBC isolation from large blood samples without centrifugation, RBC lysis, cell biomarkers, and chemical pre-treatments make this method an ideal choice for downstream cell study platforms.

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