Three-junction solar cell with improved band gap structure

Abstract

The invention discloses a three-junction solar cell with an improved band gap structure. The three-junction solar cell comprises a three-junction solar cell unit. An antireflection film and a first metal electrode are arranged on the upper surface and the lower surface of the three-junction solar cell unit respectively, and a second metal electrode is arranged on the upper surface of the antireflection film. A semiconductor Ge single crystal wafer serves as a substrate of the three-junction solar cell unit, and the three-junction solar cell unit sequentially comprises a bottom cell, a middle cell and a top cell from bottom to top according to a stratified structure, the bottom cell is a Ge solar cell, the middle cell is a GaInNAs solar cell, the top cell is a GaInP solar cell, the bottom cell and the middle cell are connected through a first tunnel junction, and the middle cell and the top cell are connected through a second tunnel junction. By means of the three-junction solar cell, the band gap combination of the three-junction cell can be optimized, the overall short-circuit current of the three-junction cell is increased, and the photoelectric conversion efficiency of the three-junction cell is finally improved.

Description

technical field [0001] The invention relates to the technical field of solar photovoltaics, in particular to a triple-junction solar cell with an optimized bandgap structure. Background technique [0002] The photoelectric conversion efficiency of traditional gallium arsenide multi-junction solar cells is much higher than that of traditional crystalline silicon cells because it can make full use of more solar spectrum ranges. At present, the preparation technology of GaInP / GaInAs / Ge triple-junction solar cells is very mature, and has been maturely applied in concentrated photovoltaic (CPV) systems. However, the band gap structure 1.85eV / 1.40eV / 0.66eV based on the lattice-matched GaInP / GaInAs / Ge triple-junction cell is not optimal, and the solar spectrum energy absorbed by the Ge bottom cell under this structure is higher than that of the middle cell and the top cell. The battery absorbs much more, so the short-circuit current of the Ge battery can reach nearly twice that of...

AI Technical Summary

Problems solved by technology

However, the band gap structure 1.85eV / 1.40eV / 0.66eV based on the lattice-matched GaInP / GaInAs / Ge triple-junction cell is not optimal, and the solar spectrum energy absorbed by the Ge bottom cell under this structure is higher than that of the middle cell and the top cell. The battery absorbs much more, so the short-circuit current of the Ge battery can reach nearly twice that of the middle and top batteries (V. Sabnis, H. Yuen, and M. Wiemer, AIP Conf. Proc. 1477 (2012) 14), due to the current limitation of the series structure, a large part of the spectral energy cannot be fully converted and utilized, which limits the improvement of battery performance

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