TY - GEN
T1 - Effects of Amorphous Silicon Thickness Variation on Infrared-Tuned Silicon Heterojunction Bottom Cells
AU - Shi, Jianwei
AU - Yu, Zhengshan J.
AU - Mehdi Leilaeioun, Ashling
AU - Fisher, Kathryn
AU - Holman, Zachary C.
N1 - Funding Information:
This material is based upon work primarily supported by the Engineering Research Center Program of the National Science Foundation and the Office of Energy Efficiency and Renewable Energy of the Department of Energy under NSF Cooperative Agreement No. EEC-1041895. The information, data, and work presented herein were funded in part by the U.S. Department of Energy PVRD2 program under Award Number DE-EE0008167. Support was also provided by the Research Corporation for Science Advancement through Scialog Collaborative Innovation Award Number 23460.
Publisher Copyright:
© 2019 IEEE.
PY - 2019/6
Y1 - 2019/6
N2 - Silicon-based tandem cells are promising to surpass the 29.4% efficiency limit of single-junction silicon solar cells. Silicon heterojunction (SHJ) solar cells are an excellent choice for the bottom cell in tandems because of their record-high open-circuit voltage and excellent spectral efficiency at near-infrared wavelengths. However, the hydrogenated amorphous silicon (aSi:H) properties of SHJ cells have not been optimized for tandem applications. In this work, we vary the front intrinsic and doped a-Si:H layer thicknesses in SHJ cells to study device performance under full-spectrum (300-1200 nm) and infrared-spectrum (700-1200 nm) illumination. We find that the design rules for the front a-Si:H layer stack are surprisingly similar in both cases, but the SHJ cell efficiency variance greatly decreases - by a factor of 3 to 4 - when changing from full-spectrum to infrared-spectrum illumination. That is, cells with substantial a-Si:H thickness variation have narrow efficiency and current distributions when used as bottom cells, which is desirable for subsequent tandem solar module integration. From a manufacturing perspective, there is no need to make additional a-Si:H adjustments specifically for bottom cells, and much higher a-Si:H thickness non-uniformity can be tolerated, which may allow for cheaper deposition tools.
AB - Silicon-based tandem cells are promising to surpass the 29.4% efficiency limit of single-junction silicon solar cells. Silicon heterojunction (SHJ) solar cells are an excellent choice for the bottom cell in tandems because of their record-high open-circuit voltage and excellent spectral efficiency at near-infrared wavelengths. However, the hydrogenated amorphous silicon (aSi:H) properties of SHJ cells have not been optimized for tandem applications. In this work, we vary the front intrinsic and doped a-Si:H layer thicknesses in SHJ cells to study device performance under full-spectrum (300-1200 nm) and infrared-spectrum (700-1200 nm) illumination. We find that the design rules for the front a-Si:H layer stack are surprisingly similar in both cases, but the SHJ cell efficiency variance greatly decreases - by a factor of 3 to 4 - when changing from full-spectrum to infrared-spectrum illumination. That is, cells with substantial a-Si:H thickness variation have narrow efficiency and current distributions when used as bottom cells, which is desirable for subsequent tandem solar module integration. From a manufacturing perspective, there is no need to make additional a-Si:H adjustments specifically for bottom cells, and much higher a-Si:H thickness non-uniformity can be tolerated, which may allow for cheaper deposition tools.
KW - amorphous silicon
KW - heterojunction
KW - infrared
KW - solar cell
KW - tandem
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U2 - 10.1109/PVSC40753.2019.8981336
DO - 10.1109/PVSC40753.2019.8981336
M3 - Conference contribution
AN - SCOPUS:85081592201
T3 - Conference Record of the IEEE Photovoltaic Specialists Conference
SP - 750
EP - 755
BT - 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 46th IEEE Photovoltaic Specialists Conference, PVSC 2019
Y2 - 16 June 2019 through 21 June 2019
ER -