Double-side growth four-junction solar cell with reflecting layer and preparation method thereof

Abstract

The invention discloses a double-side growth four-junction solar cell with a reflecting layer and a preparation method thereof, and the solar cell comprises a GaAs substrate; the GaAs substrate is an n-type GaAs single-crystal slice that is polished in two sides; a GaAs buffer layer, a first tunnel junction, a AlGaAs / GaInAs DBR reflecting layer, a GaInNAs sub-cell, a second tunnel junction, a AlAs / AlGaAs DBR reflecting layer, a GaAs sub-cell, a third tunnel junction, a GaInP sub-cell, an ohmic contact layer, an antireflection coating, and a front electrode grow on the upper surface of the GaAs substrate from top to bottom; a Ga1-zInzP strain buffer layer, a Ga1-xInxAs sub-cell and a back electrode are provided on the lower surface of the GaAs substrate in order. According to the invention, photon absorption efficiency can be raised; at the same time, the advantages of the four-junction solar cell can play their roles; the integral open-circuit voltage and a fill factor of the GaAs multi-junction cell can be raised; and the photoelectric conversion efficiency of the cell can be improved finally.

Description

Technical field [0001] The invention relates to the technical field of solar photovoltaics, in particular to a double-sided growth four-junction solar cell with a reflective layer and a preparation method thereof. Background technique [0002] At present, traditional gallium arsenide multi-junction solar cells are widely used in concentrated photovoltaic power generation (CPV) systems and space power systems because their conversion efficiency is significantly higher than that of crystalline silicon cells. The mainstream structure of gallium arsenide multi-junction battery is GaInP / GaInAs / Ge triple-junction solar cell composed of GaInP, GaInAs and Ge sub-cells. The battery structure maintains lattice matching as a whole, and the band gap structure is 1.85 / 1.40 / 0.67eV. However, for the solar spectrum, due to the large band gap gap between the GaInAs sub-cell and the Ge sub-cell, the band gap combination of this triple junction cell is not optimal. The solar spectrum absorbed by th...

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Problems solved by technology

[0005] However, due to the high background carrier concentration of GaInNAs materials, this will make the minority carrier diffusion length smaller

In this case, if the GaInNAs material grows too thick, it cannot achieve the effect of effectively collecting photogenerated carriers; on the contrary, if the GaInNAs material grows too thin, it cannot fully absorb the photons of the corresponding wavelength band, and the consequence is the short-circuit current of the GaInNAs battery. Low

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