Analysis of perimeter recombination in the subcells of GaInP/GaAs/Ge triple-junction solar cells

• Published in: Progress in photovoltaics 2015-07, Vol.23 (7), p.874-882
• Main Authors: Espinet-González, P., Rey-Stolle, I., Ochoa, M., Algora, C., García, I., Barrigón, E.
• Format: Article
• Language: English
• Subjects: concentration; CPV; Devices; Diodes; Gallium arsenide; Gallium arsenides; Germanium; multijunction; perimeter; Photovoltaic cells; photovoltaics; recombination; Solar cells; Volt-ampere characteristics
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.2501

This paper studies the recombination at the perimeter in the subcells that constitute a GaInP/GaAs/Ge lattice‐matched triple‐junction solar cell. For that, diodes of different sizes and consequently different perimeter/area ratios have been manufactured in single‐junction solar cells resembling the subcells in a triple‐junction solar cell. It has been found that neither in GaInP nor in Ge solar cells the recombination at the perimeter is significant in devices as small as 500 μm × 500μm(2.5 ⋅ 10 − 3 cm2) in GaInP and 250μm  × 250μm (6.25 ⋅ 10 − 4cm2) in Ge. However, in GaAs, the recombination at the perimeter is not negligible at low voltages even in devices as large as 1cm2, and it is the main limiting recombination factor in the open circuit voltage even at high concentrations in solar cells of 250 μm  × 250μm (6.25 ⋅ 10 − 4 cm2) or smaller. Therefore, the recombination at the perimeter in GaAs should be taken into account when optimizing triple‐junction solar cells. Copyright © 2014 John Wiley & Sons, Ltd. Taking into account that concentrator multijunction solar cells are small solar cells, the recombination at the perimeter could be significant. Therefore, in this work, the recombination at the perimeter has been studied in the subcells that makeup a GaInP/Ga(In)As/Ge triple‐junction solar cell. For that, diodes of different sizes and consequently different perimeter to area ratios have been manufactured. Their dark I–V curves have been measured, and the current density and linear current density versus voltage curves have been analyzed.