Refined optoelectronic properties of silicon nanowires for improving photovoltaic properties of crystalline solar cells: a simulation study (original) (raw)
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Fabrication of a Silicon Nanowire Solar Cell on a Silicon-on-Insulator Substrate
Applied Sciences, 2019
This study proposes metal-assisted chemical etching (MAE) as a facile method to fabricate silicon nanowire (SiNW) array structures, with high optical confinement for thin crystalline silicon solar cells. Conventional SiNW arrays are generally fabricated on Si wafer substrates. However, tests on conventional SiNW-based solar cells cannot determine whether the photo-current is derived from SiNWs or from the Si wafer. Herein, SiNW arrays were fabricated on a silicon-on-insulator substrate with a 10-μm-thick silicon layer for measuring the photocurrent of the SiNW only. The 9 μm-long p-type SiNW arrays were applied to a solar cell structure fabricated using an n-type H-doped amorphous Si layer, thereby confirming the photovoltaic effect. However, the device exhibited a conversion efficiency of 0.0017% because of a low short-circuit current (Jsc) and a low open-circuit voltage (Voc). The low Jsc resulted from a high series resistance and high absorption loss from the amorphous Si layer, ...
Performance limitation of Si nanowire solar cells: Effects of nanowire length and surface defects
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019
In Si nanowire (SiNW) solar cells enhanced light confinement property in addition to decoupling of charge carrier collection and light absorption directions plays a significant role to resolve the draw backs of bulk Si solar cells. In this report we have studied the dependence of the phovoltaic properties of Si NW array solar cells on the SiNW length and enhanced surface defect states as a result of enhanced surface area of the NWs. The SiNW arrays have been fabricated using metal catalyzed electroless etching (MCEE) technique. p-n junction has been produced by spin-ondopant technique followed by thermal diffusion process. Front and rear electrodes have been deposited by e-beam evaporation techniques. SiNW lengths have been controlled from ~ 320 nm to 6.4 m by controlling the parameters of MCEE technique. Photovoltaic properties of the solar cells have been characterized by measuring quantum efficiency and photocurrent density vs. voltage characteristics. Morphological studies have been carried out by using scanning electron microscopy. Reduction in light trapping capability comes at the benefit of reduced surface defects. The reduction of surface defects has been proved to be more advantageous in comparison to the decrement of light trapping capability. The major contribution to the changes in cell efficiency comes from the enhancement of short circuit current density with a very weak dependence on open circuit voltage. This work is beneficial for the production of commercial Si solar cells where SiNW arrays could be used as an antireflection coating instead of using separate antireflection layers. Thus could reduced the production cost.
Effect of nanowire length on the performance of silicon nanowires based solar cell
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2014
Currently, silicon nanowires (SiNWs) are attracting attention as promising candidate materials for developing the next-generation solar cells to realize both low cost and high efficiency due to their unique structural, electrical, and optical properties. In this paper, a vertical-aligned SiNWs array has been prepared by metal-assistant chemical etching technique and implemented on SiNW array textured solar cells for photovoltaic application. The shape and size of SiNWs were controlled by etching time of 30 min, 45 min and 60 min with the length of SiNWs of 4 μm, 6 μm and 8 μm, respectively. The etching rate was estimated to be about 133 nm per minute. The optical properties of a SiNWs array with different lengths were investigated in terms of optical reflection property. Less than 6% reflection ratio from 300 nm to 800 nm wavelength was achieved. In addition, I-V characteristic was used to estimate the dependence of the SiNWs length on the performance of SiNWs based solar cell. Conservation efficiencies were achieved of 1.71%, 2.19%, and 2.39% corresponding to 4 μm, 6 μm and 8 μm SiNWs in length, respectively.
Wet chemically prepared silicon nanowire arrays on low-cost substrates for photovoltaic applications
physica status solidi (a), 2013
Silicon nanowire (SiNW) based solar cells are a promising candidate for third generation solar cells with high efficiency, which will further reduce the cost of the PV modules, making it competitive with conventional energy sources. In this paper the wet chemical etching process for generating silicon nanowires is investigated on different low-cost substrate materials. These nanowires are useful for a radial pn-junction solar cell with core-shell configuration, which allows for using absorber materials with low-carrier lifetime. In this work, wet chemical nanowire etching is applied to edge-defined film-fed growth (EFG) mc-Si wafers, mc-Si wafers made from metallurgical grade Si, multicrystalline (mc-Si) thin films deposited on glass, and thin crystallized films deposited on mc-Si wafers produced from metallurgical grade Si. A proof of concept for using lowcost materials in PV is demonstrated for SiNWs prepared on mc-Si wafer produced from highly doped MG-Si.
Fabrication of silicon nanowire arrays based solar cell with improved performance
Solar Energy Materials …, 2011
We report fabrication of solar cell (n + -p-p + structure) on black silicon substrates consisting of silicon nanowire (SiNW) arrays prepared by Ag induced wet chemical etching process in aqueous HF-AgNO 3 solution. SiNW arrays surface has low reflectivity ( o5%) in the entire spectral range (400-1100 nm) of interest for solar cells. The solar cells were fabricated by conventional cell fabrication protocol. Performance of three types of cells, namely cell with SiNW over the entire front surface, cell with SiNW only in the active device area and control cell (on planar surface), has been compared. It was found that cell based on selectively grown shorter length SiNW arrays has the best cell performance.
Dependence of performance of Si nanowire solar cells on geometry of the nanowires
The dependence of performance of silicon nanowires (SiNWs) solar cells on the growth condition of the SiNWs has been described. Metal-assisted electroless etching (MAE) technique has been used to grow SiNWs array. Different concentration of aqueous solution containing AgNO 3 and HF for Ag deposition is used. The diameter and density of SiNWs are found to be dependent on concentration of solution used for Ag deposition. The diameter and density of SiNWs have been used to calculate the filling ratio of the SINWs arrays. The filling ratio is increased with increase in AgNO 3 concentration, whereas it is decreased with increase in HF concentration. The minimum reflectance value achieved is ∼1% for SiNWs of length of ∼1.2 m in the wavelength range of 300-1000 nm. The performance and diode parameters strongly depend on the geometry of SiNWs. The maximum short circuit current density achieved is 35.6 mA/cm 2 . The conversion efficiency of solar cell is 9.73% for SiNWs with length, diameter, and wire density of ∼1.2 m, ∼75 nm, and 90 m −2 , respectively.
ACS Omega, 2018
Si nanowires (SiNWs) produced by metal-assisted chemical etching on n-type Si were investigated for their use as a light-trapping material in c-Si solar cells. The nanowires were fabricated before junction formation (on a lightly doped Si substrate) so that their core was bulk and nonporous. The above fabrication process was implemented in solar cell fabrication. The SiNW reflectivity was tested at different steps of solar cell processing and found to be lower than that of conventional random pyramids used in c-Si solar cells. Contact formation on the front side of the cell was investigated by considering metal deposition either directly on the nanowires or on bulk areas in between the nanowire areas. The superiority of this second case was demonstrated. Three different Si nanowire lengths were investigated, namely, 0.5, 1, and 1.5 μm, the case of 1 μm giving better results in terms of solar cell characteristics and external quantum efficiency. The electronic quality of the Si nanowire surface was investigated using the corresponding metaloxide-semiconductor capacitors with atomic-layer-deposited alumina dielectric. Successful reduction of surface recombination centers at the large Si nanowire surface was achieved by reducing structural defects at their surface through a specific chemical treatment. Finally, using the determined optimized conditions for Si nanowire formation, chemical cleaning, and process implementation in solar cell fabrication, we demonstrated ∼45% increase in solar cell efficiency with 1 μm SiNWs compared to that from a flat reference cell processed under similar conditions. The above study was made on test solar cells without surface passivation.
Journal of Nano- and Electronic Physics, 2017
In this study, we present the effect of annealing time on the power conversion efficiency (PCE) of silicon nanowire (SiNW) based solar cell prepared by wet diffusion technique. P-typed SiNW arrays were prepared by metal assisted chemical etching (MACE) method using aqueous solution including HF (4.6 M) and AgNO3 (0.02 M). The prepared SiNWs have V-shaped structures with the wall thickness in a range from 10-50 nm and the average length of 1.5 m. The reflectance of SiNW array remained less than 20 % and lower compared to that of planar Si (38 %) in the range of 300-1000 nm due to the subwavelength light trapping and collective light scattering interactions. The wet diffusion technique was used to making p-n junctions in solar cell structure with different annealing time at 850 C. The obtained results demonstrated that the PCE increases when increasing the annealing time from 30 min to 45 min then decreases with 60 min. The highest PCE obtained with cell annealed for 45 min was measured to be 2.2 % and about 2 times and 5 times higher compared to cell annealed for 60 min and 30 min, respectively. The dependence of PCE on the annealing time is attributed to the difference in the doping diffusion depth.