TITLE:
Approaches for High-Efficiency III-V/Si Tandem Solar Cells
AUTHORS:
Masafumi Yamaguchi, Kan-Hua Lee, Patrick Schygulla, Frank Dimroth, Tatsuya Takamoto, Ryo Ozaki, Kyotaro Nakamura, Nobuaki Kojima, Yoshio Ohshita
KEYWORDS:
High-Efficiency, Solar Cells, Si Tandem, Multi-Junction, Efficiency Analysis
JOURNAL NAME:
Energy and Power Engineering,
Vol.13 No.12,
December
17,
2021
ABSTRACT: The Si tandem solar cells are very attractive for realizing high efficiency
and low cost. This paper overviews current status of III-V/Si tandem solar
cells including our results. The analytical results for efficiency potential of
Si tandem solar cells and loss analysis of Si bottom cells as well as bandgap
energy optimization of sub-cells are presented. The 2-junction and 3-junction
Si tandem solar cells have potential efficiencies of 36% and 42%, respectively.
ERE (external radiative efficiency) analysis for Si solar cells is analyzed in
order to clarify properties of Si bottom
solar cells. Properties of single-crystalline Si heterojunction solar cell fabricated in this study were analyzed. The current status of efficiencies of our Si bottom cell, upper III-V 2-junction
solar cell and III-V/Si 3-junction tandem solar cell was shown to be 5.2% and
28.6% and 33.8%. Achievement of Jsc of 12 mA/cm2 for Si bottom cell is necessary to realize
high-efficiency 3-junction Si tandem solar cells with an efficiency of more than 37%. In addition, this paper presents ERE analysis of III-V
2-junction upper solar cells for improving III-V/Si 3-junction tandem solar
cells. Several ways to improve efficiency of III-V/Si 3-junction tandem solar
cells by reducing non-radiative recombination, optical and resistance losses
are shown.