Spectral responsivity measurements of DSSC devices at low chopping frequency (1 Hz)

Abstract

Dye-sensitized Solar Cells (DSSCs) are generally known to possess a slow response time for photocurrent generation by incident light. Electrical power measurements can only be accurately made if sufficient time is allowed to complete photocurrent generation, in contrast to the case of c-Si solar cells. There are two methods which can satisfactorily measure the spectral responsivity (SR) of DSSCs, i.e., the “AC method” and “DC method”. Of these two, the AC method in the IEC 60904-8 standard is the normal procedure for SR measurement of solar cells. A new setup implemented at ESTI for the spectral responsivity measurement of DSSCs is presented, making use of a low frequency (≤1 Hz) chopped monochromatic beam produced from a continuous broadband light source with band-pass filters and lock‐in technique for measurements of the signals. The beam is projected onto the device under test (DUT) and superimposed over continuous white bias light. The procedure for the determination of the absolute spectral responsivity is presented, and the influence of the slow response for photocurrent generation typical of DSSC devices is investigated. The results obtained with the new setup for standard c-Si solar cells and DSSCs are reported and discussed, providing a validation of the system.