An aluminum-free high-efficiency six-junction solar cell and its preparation method

Abstract

The invention discloses an aluminum-free high-efficiency six-junction solar cell and a preparation method thereof. A GaInAs / GaInP buffer layer, a first tunnel junction, a GaNxSb3xAs1-4x sub-cell, a second tunnel junction,a GaNySb3yAs1-4y sub-cell, a third tunnel junction, a GaInAs sub-cell, a fourth tunnel junction, a GaInAsP sub-cell, a fifth tunnel junction, a graded buff layer and a GaInP sub-cell are grown on the top surface of a Ge substrate by metal organic chemical vapor deposition or molecular beam epitaxy in a laminated structure. The invention can improve the collection efficiency ofthe sub-battery containing the wide band gap material and the dilute nitrogen compound material, increase the short-circuit current of the six-junction battery, save the production cost, finally exert the advantages of the six-junction battery, and improve the overall photoelectric conversion efficiency of the battery.

Description

technical field [0001] The invention relates to the technical field of solar photovoltaic power generation, in particular to an aluminum-free high-efficiency six-junction solar cell and a preparation method thereof. Background technique [0002] At present, solar cells can be roughly divided into three categories from the perspective of technological development history: the first generation of crystalline silicon solar cells, the second generation of thin-film solar cells and the third generation of gallium arsenide concentrating (multi-junction) solar cells. Gallium arsenide multi-junction solar cells are widely used in concentrated photovoltaic (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 solar cells is a GaInP / GaInAs / Ge triple-junction solar cell composed of GaInP, GaInAs and Ge sub-cells. The cell structure maintains la...

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Problems solved by technology

[0005] In recent years, researchers have found that in the dilute nitrogen compound GaInNAs material, by adjusting the composition of In and N, and keeping the In composition about 3 times that of the N composition, the optical band gap of GaInNAs can reach 0.9-1.4eV , and match the Ge substrate lattice, however, in the actual preparation process of GaInNAs materials, because GaInNAs needs low temperature growth to ensure the effective incorporation of N atoms, a large number of C atoms will be introduced into the material at the same time, resulting in background carrier The concentration is too high, affecting the minority carrier diffusion length

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