Progress in the measurement of multi-junction devices at ISE
The ISE calibration laboratory is extending its facilities to measure multi-junction devices. In this paper we discuss a new reference cell method with software pre-selection of the simulator setting which has a high potential for reducing measurement time. We report about the progress in setting up a triple source solar simulator for large area solar cells with an in situ measurement of the spectrum using a calibrated spectroradiometer from 350 nm to 1500 nm. We present details of our high precision spectral response facility for solar cells of up to 10 x 10 qm over a wavelength range of 320 nm to 1500 nm. We analysed the propagation of systematic spectral uncertainties: Typically a 10% spectral uncertainty leads to a 1.5% uncertainty in short circuit current when the spectral mismatch method is used. In conclusion, we give a short outlook concerning the planned extensions and improvements of the facility, which is already capable of characterising multi-junction devices.