Spectrometric Characterization for Triple-Junction Solar Cells

Spectrometric characterization allows for accurate determination of the current matching point and investigation of sub-cell properties of multi-junction solar cells. It is widely used for dual-junction solar cells. Although the concept is suggested for triple-junction solar cells, it is only applied for the variation of two sub-cells. In this work, the applicability and evaluation procedure for a systematic variation of all three sub-cells of a triple-junction solar cell are presented. Clearly defined measurement conditions are derived which allow for meaningful characterization and comparisons of different triple-junction devices. The presented procedure is exemplarily tested on a III-V on silicon triple-junction solar cell using an light-emitting diode-based solar simulator where all needed spectral conditions can be calculated in advance and accordingly adjusted. Spectral conditions around the air mass 1.5 global spectrum are chosen and a fit routine to determine the current matching point from the discrete measurement points is proposed and validated by a measurement with a higher resolution around the current matching point. Finally, it is shown that the spectral conditions applied during the measurement also reflect outdoor conditions. This highlights the relevance of the presented procedure beyond the determination of the current-matching conditions. In spectrometric characterization, current-voltage curves of multi-junction solar cells are measured under different defined spectral conditions allowing for accurate determination of the current matching point. Herein, this method is extended from dual-junction to triple-junction solar cells. First, the method is presented. Afterward, the application and evaluation are exemplarily shown for a III-V on silicon triple-junction solar cell.image (c) 2023 WILEY-VCH GmbH