Optical Simulations of the Effects of Transparent Conducting Oxide Interface Layers on Amorphous Silicon Solar Cell Performance

2001 ◽  
Vol 664 ◽  
Author(s):  
Gelio M. Ferreira ◽  
Andre S. Ferlauto ◽  
Pablo I. Rovira ◽  
Chi Chen ◽  
Hien V. Nguyen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Cell Structure ◽  
Transparent Conducting Oxide ◽  
Oxide Interface ◽  
Solar Cell Performance ◽  
Beneficial Effects ◽  
Amorphous Silicon Solar Cell ◽  
Interface Layers

ABSTRACTSpectroscopic ellipsometry (SE) analysis of so-called “specular” (macroscopically smooth) and “textured” (macroscopically rough) thin film amorphous silicon (a-Si:H) based solar cell structures demonstrates the need to incorporate interface layers into the multilayer stack in order to simulate the observed Stokes vector of the specularly-reflected beam. In most cases, these layers can be attributed to microscopic roughness (e.g., at the SnO2/p-layer/i-layer interface in a-Si:H p-i-n solar cells), as verified by atomic force microscopy (AFM). In limited cases, the layers may include regions wherein chemical intermixing also occurs (e.g., at the ZnO/Ag interface in back-reflectors), particularly for overlying films prepared by sputtering. In spite of the clear evidence for the existence of interface layers, they have been neglected in previous simulations of the optical quantum efficiency (QE) of the solar cells. In this study, we incorporate the experimentally- observed characteristics of interface layers as input into optical models for the p-i-n solar cell structure. In this way, we demonstrate the beneficial effects of SnO2/p/i interface microroughness as an anti-reflector and the detrimental effects of the ZnO/Ag interlayer as a parasitic absorber.

Amorphous Silicon Solar Cell Techniques for High Temperature and/or Reactive Deposition Conditions

1999 ◽  
Vol 557 ◽  
Author(s):  
M. Kanbe ◽  
T. Komaru ◽  
K. Fukutani ◽  
T. Kamiya ◽  
C.M. Fortmann ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Silicon Solar Cell ◽  
Hydrogen Diffusion ◽  
Hydrogen Reduction ◽  
Poor Performance ◽  
N Deposition ◽  
Solar Cell Performance ◽  
Amorphous Silicon Solar Cell

AbstractSeveral promising new methods for amorphous silicon solar cell preparation involve high substrate temperatures and/or very reactive atmospheres. When incorporated into solar cells, the performance of these layers has often been less than expected due to enhanced diffusion and/or chemical reactions. This poor performance results from the harsh deposition environments. Deleterious effects include darken of TCO coated glass substrates due to hydrogen diffusion to and hydrogen reduction at the TCO interface when solar cells are prepared in the p-i-n deposition sequence. Alternatively, the deposition of TCO layers onto amorphous layers also involves rather harsh oxidizing conditions that have a deleterious effect on the top most amorphous silicon-based p-layers. Strategic use of blocking layers results in remarkably improved solar cell performance. A thin Cr layer (probably becoming Cr2O3) shows ability to improve the performance of both n-ip and p-i-n solar cells by inhibiting both O and H diffusion.

Annealing Kinetics of Amorphous Silicon Alloy Solar Cells Made at Various Deposition Rates

2001 ◽  
Vol 664 ◽  
Author(s):  
Baojie Yana ◽  
Jeffrey Yanga ◽  
Kenneth Lord ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Frequency ◽  
Room Temperature ◽  
Defect Density ◽  
Very High Frequency ◽  
Solar Cell Performance ◽  
Kinetics Of ◽  
Very High

ABSTRACTA systematic study has been made of the annealing kinetics of amorphous silicon (a-Si) alloy solar cells. The cells were deposited at various rates using H2 dilution with radio frequency (RF) and modified very high frequency (MVHF) glow discharge. In order to minimize the effect of annealing during light soaking, the solar cells were degraded under 30 suns at room temperature to quickly reach their saturated states. The samples were then annealed at an elevated temperature. The J-V characteristics were recorded as a function of annealing time. The correlation of solar cell performance and defect density in the intrinsic layer was obtained by computer simulation. Finally, the annealing activation energy distribution (Ea) was deduced by fitting the experimental data to a theoretical model. The results show that the RF low rate solar cell with high H2 dilution has the lowest Ea and the narrowest distribution, while the RF cell with no H2 dilution has the highest Ea and the broadest distribution. The MVHF cell made at 8Å/s withhigh H2 dilution shows a lower Ea and a narrower distribution than the RF cell made at 3 Å/s, despite the higher rate. We conclude that different annealing kinetics plays an important role in determining the stabilized performance of a-Si alloy solar cells.

Metamorphic GaInP-GaInAs Layers for Photovoltaic Applications

2004 ◽  
Vol 836 ◽  
Author(s):  
A. W. Bett ◽  
C. Baur ◽  
F. Dimroth ◽  
J. Schöne
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Triple Junction ◽  
Cell Structure ◽  
X Ray Diffraction ◽  
Solar Cell Performance ◽  
Transmission Electron ◽  
Layer Structures ◽  
Buffer Material ◽  
Metal Organic

ABSTRACTGaxIn1−xAs and GayIn1−yP layers were grown lattice mismatched to GaAs and Ge by low-pressure metal organic vapor phase epitaxy (LP-MOPVE). These materials are very promising for further increasing the efficiency of monolithic triple-junction solar cells. Different buffer layer structures were realized. Transmission electron microscopy and x-ray diffraction analysis were used to characterize the quality of the crystal. Both linear and step-graded buffers in GaxIn1−xAs were successfully used under an active solar cell structure. GayIn1−yP as buffer material showed a worse performance. Excellent solar cell performance was achieved for lattice mismatched single-, dual- and triple-junction solar cells.

Amorphous Silicon Alloy Materials and Solar Cells Near the Threshold of Microcrystallinity

1999 ◽  
Vol 557 ◽  
Author(s):  
J. Yang ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Triple Junction ◽  
High Efficiency ◽  
Spectral Response ◽  
High Quality ◽  
Silicon Alloys ◽  
Solar Cell Performance ◽  
Hydrogen Dilution

AbstractOne of the most effective techniques used to obtain high quality amorphous silicon alloys is the use of hydrogen dilution during film growth. The resultant material exhibits a more ordered microstructure and gives rise to high efficiency solar cells. As the hydrogen dilution increases, however, a threshold is reached, beyond which microcrystallites begin to form rapidly. In this paper, we review some of the interesting features associated with the thin film materials obtained from various hydrogen dilutions. They include the observation of linear-like objects in the TEM micrograph, a shift of the principal Si TO band in the Raman spectrum, a sharp, low temperature peak in the H2 evolution spectrum, a shift of the wagging mode in the IR spectrum, and a narrowing of the Si (111) peak in the X-ray diffraction pattern. These spectroscopic tools have allowed us to optimize deposition conditions to near the threshold of microcrystallinity and obtain desired high quality materials. Incorporation of the improved materials into device configuration has significantly enhanced the solar cell performance. Using a spectral-splitting, triple-junction configuration, the spectral response of a typical high efficiency device spans from below 350 nm to beyond 950 nm with a peak quantum efficiency exceeding 90%; the triple stack generates a photocurrent of 27 mA/cm2. This paper describes the effect of the improved materials on various solar cell structures, including a 13% active-area, stable triple-junction device.

Amorphous Silicon Films from Dichlorosilane and SiH4 for Solar Cells

1996 ◽  
Vol 420 ◽  
Author(s):  
A. M. Payne ◽  
S. Wagner
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Transport Properties ◽  
Electronic Transport ◽  
Silicon Films ◽  
Cell Performance ◽  
Solar Cell Performance ◽  
Electronic Transport Properties ◽  
Standard Cells

AbstractWe have deposited amorphous silicon films from mixtures of dichlorosilane (SiH2C12, DCS), and silane (SiH4) and made the first p-i-n solar cells using i-layers of this material. We measured optical and electronic transport properties of the DCS-derived films and relate them to the solar cell performance. The DCS cells are compared to standard cells made with SilH4.

Buffer Layers for Narrow Bandgap A-SIGE Solar Cells

1999 ◽  
Vol 557 ◽  
Author(s):  
X. B. Liao ◽  
J. Walker ◽  
X. Deng
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Hydrogenated Amorphous Silicon ◽  
Absorber Layer ◽  
Buffer Layers ◽  
Narrow Bandgap ◽  
Interface Layers ◽  
Hydrogenated Amorphous

AbstractIn high efficiency narrow bandgap (NBG) a-SiGe solar cells, thin buffer layers of unalloyed hydrogenated amorphous silicon (a-Si) are usually used at the interfaces between the a-SiGe intrinsic layer and the doped layers. We investigated the effect of inserting additional a-SiGe interface layers between these a-Si buffer layers and the a-SiGe absorber layer. We found that such additional interface layers increase solar cell VOC and FF sizably, most likely due to the reduction or elimination of the abrupt bandgap discontinuity between the a-SiGe absorber layer and the a-Si buffer layers. With these improved narrow bandgap solar cells incorporated into the fabrication of triple-junction a-Si based solar cells, we obtained triple cells with initial efficiency of 10.6%.

Influence of Transparent Conducting Oxide on Amorphous Silicon Solar Cell Performance

1986 ◽  
Vol 70 ◽  
Author(s):  
Chris Walker ◽  
Russell Hollingsworth ◽  
Joe del Cueto ◽  
Arun Madan
Keyword(s):  
Solar Cell ◽  
Silicon Solar Cell ◽  
Spectral Response ◽  
Transparent Conducting Oxide ◽  
Electrical Contacts ◽  
Cell Performance ◽  
Solar Cell Performance ◽  
Conducting Oxides ◽  
Amorphous Silicon Solar Cell ◽  
Transparent Conducting

The use of transparent conducting oxides (TCO) as electrical contacts in a-Si:H solar cells has stimulated interest in the multitude of effects that these layers have on a-Si:H solar cell performance. The study of a-Si:H p-i-n junctions using a TCO contact involves many factors such as, interdiffusion, transmission, reflection, and resistivity. In this paper, we attempt to distinguish between these factors through the role they play in determining the solar cell device performance. Devices were characterized via dark and illuminated current vs. voltage (I-V) measurements, and spectral response. It was found that the properties of the TCO have an important role in influencing FF and Jsc in the devices.

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