High-speed broadband quantum efficiency determination of solar cells

The investigation of the external quantum efficiency (EQE) of optical sensors and solar cells plays a major role in device characterization. As a key parameter, the EQE reveals important information about optical and electrical properties. In the field of photovoltaics, the EQE is, moreover, mandatory for the spectral mismatch correction in the process of device calibration. The work presented here aims for a new measurement method accelerating the time-consuming EQE determination procedure by more than two orders of magnitude. The new set-up is based on a spectrograph system with an integrated spatial light modulator operated as fast amplitude modulating element. This allows utilizing the multiplex advantage by characterizing the sensitivity of the device at various wavelengths at once. An enhanced system is presented, which covers the broadband wavelength range from 300 up to 2000 nm. Thus, it is now possible to determine the EQE of, e.g., germanium-based detectors with an accuracy comparable to standard EQE systems within a few seconds only.