Degradation mechanism analysis in temperature stress tests on Ⅲ-Ⅴ ultra-high concentrator solar cells using a 3D distributed model

摘要

A temperature stress test was carried out on GaAs single-junction solar cells to analyze the degradation suffered when working at ultra-high concentrations. The acceleration of the degradation was realized at two different temperatures: 130 ℃ and 150℃. In both cases, the degradation trend was the same, and only gradual failures were observed. A fit of the dark Ⅰ-V curve at 25 ℃ with a 3D distributed model before and after the test was done. The fit with the 3D distributed model revealed degradation at the perimeter because the recombination current in the depletion region of the perimeter increased by about fourfold after the temperature stress test. Therefore, this test did not cause any morphological change in the devices, and although the devices were isolated with silicone, the perimeter region was revealed as the most fragile component of the solar cell. Consequently, the current flowing beneath the busbar favors the progression of defects in the device in the perimeter region.