In-situ monitoring of a flashed solar simulator spectral characteristics for multijunction solar cells performance assessment

In the quest for decarbonization, industry and academia are increasing their efforts in research on innovative photovoltaic devices, and proper indoor characterization of devices in an essential element of this research, to correlate manufacturing parameters with electrical properties. For this purpose, it is essential to properly characterize artificial illumination from a solar simulator, as it might directly impact the measured quantities. To fill a literature gap, this work implements triggered high-speed spectrometers for a fast and in-situ characterization of a flashed solar simulator. A commercially available high-speed spectrometer, with a custom-made triggering circuit, was used, to evaluate the impact of supply voltage on the spectral components of the solar simulator flash during its temporal evolution. This allowed to identify some spectral lines that decreased far more slowly and never turned off during the measurement window. Supply voltage, surprisingly, introduced large effects when it’s varied to adjust irradiance. Spectral Mismatch Ratio was also determined as function of time and wavelength to provide an useful parameter when using artificial radiation. These artifacts impact the measured current-voltage curves, as evaluated on three devices. This fast spectral characterization enriched the indoor characterization procedure, allowing to identify how the extinction spectra vary with time, and to identify unexpected features introduced by changes in supply voltage.