High‐Temperature Annealing‐Induced Performance Degradation Mechanisms of GaInP/GaAs/Ge Triple‐Junction Solar Cells

As a high‐efficiency space photovoltaic technology, the high‐temperature annealing‐induced performance degradation of GaInP/GaAs/Ge triple‐junction solar cells has attracted tremendous attention. In this article, rapid annealing (temperature range 600–700 °C, heating rate 40 °C s ⁻¹ ) was performed on GaInP/GaAs/Ge solar cells, revealing that high‐temperature annealing would cause a significant reduction in the power conversion efficiency (PCE) of devices. Furthermore, a variety of advanced characterization techniques, including time‐of‐flight secondary ion mass spectrometry, in situ variable‐temperature high‐resolution transmission electron microscopy, and scanning electron microscopy analysis, were used to systematically study the impacts of annealing conditions on the performance of GaInP/GaAs/Ge solar cells as well as the performance degradation mechanisms. It is revealed that high‐temperature annealing induces a variety of negative impacts to GaInP/GaAs/Ge solar cells, such as back electrode damage, interfacial element diffusion, and semiconductor material failure, which further inhibit the carrier collection and destroy the junction regions between sub‐cells. Eventually, these unfavorable consequences lead to a significant reduction in the device PCE and even cause complete device operation failure. This work provides meaningful references for studying the temperature‐induced performance degradation of GaInP/GaAs/Ge solar cells in specific scenarios.