scholarly journals High Efficiency Triple-Junction Amorphous Silicon Alloy Photovoltaic Technology, Final Technical Report, 6 March 1998 - 15 October 2001

2001 ◽  
Author(s):  
S Guha
1998 ◽  
Vol 507 ◽  
Author(s):  
S. Guha ◽  
J. Yang ◽  
A. Banerjee ◽  
S. Sugiyama

ABSTRACTTwo significant developments took place in 1997 in the field of amorphous silicon alloy photovoltaic technology. First, a world record stable cell efficiency of 13% was demonstrated using a spectral-splitting, triple-junction structure. Second, a triple-junction photovoltaic manufacturing facility of an annual capacity of 5 MW was commissioned. In order to make the transition from R&D to production, critical material issues and deposition methods which ensure the lowest module cost per delivered watt needed to be evaluated. In this paper, we discuss some of these issues with special reference to the cell materials.


1997 ◽  
Vol 467 ◽  
Author(s):  
A. Banerjee ◽  
J. Yang ◽  
S. Guha

ABSTRACTAn initial conversion efficiency of 13.5% has been obtained on a triple-junction triple-bandgap device fabricated in a large-area deposition reactor capable of producing one-square-foot modules. The intrinsic layer of the top cell is a wide bandgap amorphous silicon alloy. The middle and bottom cells employ high quality amorphous silicon-germanium alloy. The high efficiency of the triple-junction cell is attributed to the relative reduction of the optical loss in the top tunnel junction and the improvement in the quality of the middle and bottom component cells. Triple-junction devices with initial efficiency of 13.3% have shown saturation at 11.6% after light soaking. Modules of aperture area 909cm2 have been fabricated using an assembly process similar to the one being currently used in our manufacturing line. The module design consists of onelarge-area, high-current monolithic multijunction device. The status of the small-area devices andmodules is described


1999 ◽  
Vol 557 ◽  
Author(s):  
J. Yang ◽  
S. Guha

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.


2013 ◽  
Vol 750-752 ◽  
pp. 970-973
Author(s):  
Chun Rong Xue ◽  
Xia Yun Sun

High-efficiency solar cells based on amorphous silicon technology are designed. Multi-junction amorphous silicon solar cells are discussed, how these are made and how their performance can be understood and optimized. Although significant amount of work has been carried out in the last twenty-five years, the Staebler-Wronski effect has limited the development of a-Si:H solar cells. As an alternative material, nc-Si:H has attracted remarkable attention. Taking advantage of a lower degradation in nc-Si:H than a-Si:H and a-SiGe:H alloys, the light induced degradation in triple junction structures has been minimized by designing a bottom-cell-limited current mismatching, and obtained a stable active-area cell efficiency. All this has been investigated in this paper.


1994 ◽  
Vol 345 ◽  
Author(s):  
S. Guha ◽  
J. Yang ◽  
A. Banerjee ◽  
T. Glatfelter ◽  
K. Hoffman ◽  
...  

AbstractThe key requirements for photovoltaic modules to be accepted for large-scale terrestrial applications are (i) low material cost, (ii) high efficiency with good stability, (iii) low manufacturing cost with good yield and (iv) environmental safety. Thin films of amorphous silicon alloy are inexpensive; the products are also environmentally benign. The challenge has been to improve the stable efficiency of these modules and transfer the R&D results into production. Using a multijunction, multi-bandgap approach to capture the solar spectrum more efficiently, we have developed one-square-foot modules with initial efficiency of 11.8% After 1000 h of one-sun light soaking, a stable efficiency of 10.2% was obtained. Both the efficiency values were confirmed by National Renewable Energy Laboratory. The technology has been transferred to production using an automated roll-to-roll process in which different layers of the cell structure are deposited in a continuous manner onto stainless steel rolls, 14′ wide and half a mile long. The rolls are next processed into modules of different sizes. This inexpensive manufacturing process produces high efficiency modules with subcell yields greater than 99% The key features of the technology transfer and future scope for improvement are discussed.


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