scholarly journals Light trapping in hydrogenated amorphous and nano-crystalline silicon thin film solar cells

2009 ◽  
Vol 1153 ◽  
Author(s):  
Jeffrey Yang ◽  
Baojie Yan ◽  
Guozhen Yue ◽  
Subhendu Guha
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Triple Junction ◽  
Crystalline Silicon ◽  
Light Trapping ◽  
Nano Crystalline ◽  
Back Reflectors ◽  
Back Reflector ◽  
Junction Structure ◽  
Hydrogenated Amorphous

AbstractLight trapping effect in hydrogenated amorphous silicon-germanium alloy (a-SiGe:H) and nano-crystalline silicon (nc-Si:H) thin film solar cells deposited on stainless steel substrates with various back reflectors is reviewed. Structural and optical properties of the Ag/ZnO back reflectors are systematically characterized and correlated to solar cell performance, especially the enhancement in photocurrent. The light trapping method used in our current production lines employing an a-Si:H/a-SiGe:H/a-SiGe:H triple-junction structure consists of a bi-layer of Al/ZnO back reflector with relatively thin Al and ZnO layers. Such Al/ZnO back reflectors enhance the short-circuit current density, Jsc, by ˜20% compared to bare stainless steel. In the laboratory, we use Ag/ZnO back reflector for higher Jsc and efficiency. The gain in Jsc is about ˜30% for an a-SiGe:H single-junction cell used in the bottom cell of a multi-junction structure. In recent years, we have also worked on the optimization of Ag/ZnO back reflectors for nano-crystalline silicon (nc-Si:H) solar cells. We have carried out a systematic study on the effect of texture for Ag and ZnO. We found that for a thin ZnO layer, a textured Ag layer is necessary to increase Jsc, even though the parasitic loss is higher at the Ag and ZnO interface due to the textured Ag. However, a flat Ag can be used for a thick ZnO to reduce the parasitic loss, while the light scattering is provided by the textured ZnO. The gain in Jsc for nc-Si:H solar cells on Ag/ZnO back reflectors is in the range of ˜60-75% compared to cells deposited on bare stainless steel, which is much larger than the enhancement observed for a-SiGe:H cells. The highest total current density achieved in an a-Si:H/a-SiGe:H/nc-Si:H triple-junction structure on Ag/ZnO back reflector is 28.6 mA/cm2, while it is 26.9 mA/cm2 for a high efficiency a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cell.

Plasmonic Scattering Back Reflector for Light Trapping in Flat Nano-Crystalline Silicon Solar Cells

ACS Photonics ◽  
2016 ◽  
Vol 3 (4) ◽  
pp. 685-691 ◽  
Author(s):  
Lourens van Dijk ◽  
Jorik van de Groep ◽  
Leon W. Veldhuizen ◽  
Marcel Di Vece ◽  
Albert Polman ◽  
...  
Keyword(s):  
Solar Cells ◽  
Crystalline Silicon ◽  
Light Trapping ◽  
Silicon Solar Cells ◽  
Crystalline Silicon Solar Cells ◽  
Nano Crystalline ◽  
Back Reflector

Light-trapping in Thin Film Silicon Solar Cells with a Combination of Periodic and Randomly Textured Back-reflectors

2012 ◽  
Vol 1426 ◽  
pp. 117-123 ◽  
Author(s):  
Sambit Pattnaik ◽  
Nayan Chakravarty ◽  
Rana Biswas ◽  
D. Slafer ◽  
Vikram Dalal
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Absorption ◽  
Nanoimprint Lithography ◽  
Light Trapping ◽  
Silicon Solar Cells ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Back Reflectors ◽  
Back Reflector

ABSTRACTLight trapping is essential to harvest long wavelength red and near-infrared photons in thin film silicon solar cells. Traditionally light trapping has been achieved with a randomly roughened Ag/ZnO back reflector, which scatters incoming light uniformly through all angles, and enhances currents and cell efficiencies over a flat back reflector. A new approach using periodically textured photonic-plasmonic arrays has been recently shown to be very promising for harvesting long wavelength photons, through diffraction of light and plasmonic light concentration. Here we investigate the combination of these two approaches of random scattering and plasmonic effects to increase cell performance even further. An array of periodic conical back reflectors was fabricated by nanoimprint lithography and coated with Ag. These back reflectors were systematically annealed to generate different amounts of random texture, at smaller spatial scales, superimposed on a larger scale periodic texture. nc-Si solar cells were grown on flat, periodic photonic-plasmonic substrates, and randomly roughened photonic-plasmonic substrates. There were large improvements (>20%) in the current and light absorption of the photonic-plasmonic substrates relative to flat. The additional random features introduced on the photonic-plasmonic substrates did not improve the current and light absorption further, over a large range of randomization features.

High efficiency amorphous and nanocrystalline silicon based multi-junction solar cells deposited at high rates on textured Ag/ZnO back reflectors

2009 ◽  
Vol 1153 ◽  
Author(s):  
Guozhen Yue ◽  
Laura Sivec ◽  
Baojie Yan ◽  
Jeff Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Triple Junction ◽  
High Efficiency ◽  
Nanocrystalline Silicon ◽  
Open Circuit ◽  
Very High Frequency ◽  
Solar Cell Performance ◽  
Single Junction ◽  
Back Reflectors ◽  
Back Reflector

AbstractWe report our recent progress on nc-Si:H single-junction and a-Si:H/nc-Si:H/nc-Si:H triple-junction cells made by a modified very-high-frequency (MVHF) technique at deposition rates of 10-15 Å/s. First, we studied the effect of substrate texture on the nc-Si:H single-junction solar cell performance. We found that nc-Si:H single-junction cells made on bare stainless steel (SS) have a good fill factor (FF) of ˜0.73, while it decreased to ˜0.65 when the cells were deposited on textured Ag/ZnO back reflectors. The open-circuit voltage (Voc) also decreased. We used dark current-voltage (J-V), Raman, and X-ray diffraction (XRD) measurements to characterize the material properties. The dark J-V measurement showed that the reverse saturated current was increased by a factor of ˜30 when a textured Ag/ZnO back reflector was used. Raman results revealed that the nc-Si:H intrinsic layers in the two solar cells have similar crystallinity. However, they showed a different crystallographic orientation as indicated in XRD patterns. The material grown on Ag/ZnO has more random orientation than that on SS. These experimental results suggested that the deterioration of FF in nc-Si:H solar cells on textured Ag/ZnO was caused by poor nc-Si:H quality. Based on this study, we have improved our Ag/ZnO back reflector and the quality of nc-Si:H component cells and achieved an initial and stable active-area efficiencies of 13.4% and 12.1%, respectively, in an a-Si:H/nc-Si:H/nc-Si:H triple-junction cell.

The Research of Flexible Solar Cells for Application in Solar Roof

2010 ◽  
Vol 160-162 ◽  
pp. 1394-1398
Author(s):  
Jin Song Lei ◽  
Zhao Qiang Zhang ◽  
Yong Yao
Keyword(s):  
Raman Spectroscopy ◽  
Stainless Steel ◽  
Solar Cells ◽  
Crystalline Silicon ◽  
Surface Polishing ◽  
Nano Crystalline ◽  
Current Voltage ◽  
Influence Of Substrate ◽  
Ss Substrates ◽  
Scanning Electron

In this paper, we report the deposition of nano-crystalline silicon flexible solar cells on stainless steel (SS) substrates for application in solar roof. The influence of substrate treatment on the properties of material and the solar cells was studied by Raman spectroscopy, scanning electron microscope, current-voltage (I-V), and Quantum efficiency (QE) measurements. Results suggest that the properties of the Si:H thin films and solar cells were greatly improved by the substrate treatment with surface polishing and the followed Ag/ZnO electrodes deposition.

scholarly journals Understanding of Passivation Mechanism in Heterojunction c-Si Solar Cells

2008 ◽  
Vol 1066 ◽  
Author(s):  
Michio Kondo ◽  
Stefaan De Wolf ◽  
Hiroyuki Fujiwara
Keyword(s):  
Solar Cells ◽  
Epitaxial Layer ◽  
Surface Passivation ◽  
Crystalline Silicon ◽  
Amorphous Layer ◽  
Growth Direction ◽  
Boron Doped ◽  
Junction Structure ◽  
Hydrogenated Amorphous

ABSTRACTIntrinsic hydrogenated amorphous silicon (a-Si:H) films can yield in outstanding electronic surface passivation of crystalline silicon (c-Si) wafers as utilized in the HIT (heterojunction with intrinsic thin layer) solar cells. We have studied the correlation between the passivation quality and the interface nature between thin amorphous layers and an underlying c-Si substrate for understanding the passivation mechanism. We found that a thin (∼5nm) intrinsic layer is inhomogeneous along the growth direction with the presence of a hydrogen rich layer at the interface and that completely amorphous films result in better passivation quality and device performance than an epitaxial layer. Post annealing improves carrier lifetime for the amorphous layer, whereas the annealing is detrimental for the epitaxial layer. We have also found that the passivation quality of intrinsic a Si:H(i) film deteriorates severely by the presence of a boron-doped a-Si:H(p+) overlayer due to Si-H rupture in the a-Si:H(i) film. Finally, for a passivation layer in the hetero-junction structure, a-Si1−xOx will be demonstrated in comparison with a-Si:H.

High Efficiency Hydrogenated Nanocrystalline Silicon Solar Cells Deposited at High Rates

2010 ◽  
Vol 1245 ◽  
Author(s):  
Guozhen Yue ◽  
Laura Sivec ◽  
Baojie Yan ◽  
Jeff Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Triple Junction ◽  
High Efficiency ◽  
Nanocrystalline Silicon ◽  
Active Area ◽  
Very High Frequency ◽  
Area Efficiency ◽  
Hydrogen Dilution ◽  
Back Reflectors ◽  
Junction Structure

AbstractWe report recent progress on hydrogenated nanocrystalline silicon (nc-Si:H) solar cells prepared at different deposition rates. The nc-Si:H intrinsic layer was deposited, using a modified very high frequency (MVHF) glow discharge technique, on Ag/ZnO back reflectors (BRs). The nc-Si:H material quality, especially the evolution of the nanocrystallites, was optimized using hydrogen dilution profiling. First, an initial active-area efficiency of 10.2% was achieved in a nc-Si:H single-junction cell deposited at ~5 Å/s. Using the improved nc-Si:H cell, we obtained 14.5% initial and 13.5% stable active-area efficiencies in an a-Si:H/nc-Si:H/nc-Si:H triple-junction structure. Second, we achieved a stabilized total-area efficiency of 12.5% using the same triple-junction structure but with nc-Si:H deposited at ~10 Å/s; the efficiency was measured at the National Renewable Energy Laboratory (NREL). Third, we developed a recipe using a shorter deposition time and obtained initial 13.0% and stable 12.7% active-area efficiencies for the same triple-junction design.

Triple Junction n-i-p Solar Cells with Hot-Wire Deposited Protocrystalline and Microcrystalline Silicon

2007 ◽  
Vol 989 ◽  
Author(s):  
Ruud E.I. Schropp ◽  
Hongbo Li ◽  
Ronald H.J. Franken ◽  
Jatindra K. Rath ◽  
Karine van der Werf ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Current Density ◽  
Triple Junction ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Hot Wire ◽  
Single Junction ◽  
Long Wavelength ◽  
Back Reflector

AbstractWe have implemented a number of methods to improve the performance of proto-Si/proto-SiGe/μc-Si:H triple junction n-i-p solar cells in which the top and bottom cell i-layers are deposited by Hot-Wire CVD. Firstly, a significant current enhancement is obtained by using textured Ag/ZnO back contacts developed in house instead of plain stainless steel. We studied the correlation between the integrated current density in the long wavelength range (650-1000 nm) with the back reflector surface roughness and clarified that the rms roughness from 2D AFM images correlates well with the long wavelength response of the cell when weighted with a Power Spectral Density function. For single junction 2-μm thick μc-Si:H n-i-p cells we improved the short circuit current density from the value of 15.2 mA/cm2 for plain stainless steel to 23.4 mA/cm2 for stainless steel coated with a textured Ag/ZnO back reflector.Secondly, we optimized the μc-Si:H n-type doped layer on this rough back reflector, the n/i interface, and in addition used a profiling scheme for the H2/SiH4 ratio during i-layer deposition. The H2 dilution during growth was stepwise increased in order to prevent a transition to amorphous growth. The efficiency that was reached for a single junction μc-Si:H n-i-p cell was 8.5%, which is the highest reported value for hot-wire deposited cells of this kind, whereas the deposition rate of 2.1 Å/s is about twice as high as in record cells of this type so far. Moreover, these cells show to be totally stable under light-soaking tests.Combining the above techniques, a rather thin triple junction cell (total silicon thickness 2.5 μm) has been obtained with an efficiency of 10.9%. Preliminary light-soaking tests show that this type of triple cells degrades by less than 4%.

Sign in / Sign up

Export Citation Format

Share Document