Broad-band-gap reverse three-junction solar cell with heterojunction structure

Abstract

The invention discloses a broad-band-gap reverse three-junction solar cell with a heterojunction structure. The broad-band-gap reverse three-junction solar cell contains a substrate, a buffer layer, a bottom cell, an ultra-broad band gap tunnel junction, an intermediate cell, a broad-band-gap tunnel junction, a top cell and a contact layer, wherein the parts are successively arranged from the bottom layer to the top layer according to a growth direction. The bottom cell is a AlGaInP cell, the intermediate cell is a AlGaAs-GaInP heterojunction cell, and the top cell is a GaAs cell. The intermediate cell Zn-doped AlxGaAs as a base region and Si-doped GayInP as an emitter region, wherein the x is larger than or equal to 0.05 and is less than or equal to 0.45 and the y is larger than or equal to 0.48 and is less than or equal to 0.54. The back field of the bottom cell uses the gradient Zn-doped AlzGaInP, wherein the z is larger than or equal to 0.13 and is less than or equal to 0.5. According to the broad-band-gap reverse three-junction solar cell with the heterojunction structure, the interface recombination rate can be reduced and thus a high-quality cell material can be obtained. Meanwhile, the cell short-circuit current density and the open-circuit voltage can be improved.

Description

technical field [0001] The invention relates to a solar cell, in particular to a wide bandgap reverse triple-junction solar cell containing a heterojunction structure. Background technique [0002] Due to the limitations of conventional energy such as coal, oil, and natural gas that are non-renewable and pollute the environment, solar cells can effectively utilize the continuous sunlight energy, which is an important development direction of renewable green energy. Solar cells made of III-V compound semiconductor materials have higher photoelectric conversion efficiency, stronger radiation resistance and better high temperature resistance than traditional Si solar cells, and have become the main power source of space vehicles. The reverse-grown wide-bandgap triple-junction GaAs (gallium arsenide) cell and the forward-grown narrow-bandgap double-junction InP cell are connected through semiconductor direct bonding technology, and the bonded five-junction solar cell formed is t...

AI Technical Summary

Problems solved by technology

The bandgap combination of 2.05 / 1.7 / 1.4eV is selected for GaAs-based wide-bandgap reverse triple-junction cells, which can meet the effective use of the solar spectrum. However, due to the wide bandgap of the bottom cell, it is difficult to effectively passivate the surface. The battery uses AlGaAs (aluminum gallium arsenic) material, and Si is generally used as its n-type dopant. The problem caused by this is that the DX center in Si-doped AlGaAs (DX center is formed by impurities in n-type III-V semiconductors) The introduced highly localized defect state) will become the recombination center of carriers, greatly reducing the performance of the battery

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