1 research outputs found
Electrochemical Impedance Spectroscopy of All-Perovskite Tandem Solar Cells
This work explores
electrochemical impedance spectroscopy to study
recombination and ionic processes in all-perovskite tandem solar cells.
We exploit selective excitation of each subcell to enhance or suppress
the impedance signal from each subcell, allowing study of individual
tandem subcells. We use this selective excitation methodology to show
that the recombination resistance and ionic time constants of the
wide gap subcell are increased with passivation. Furthermore, we investigate
subcell-dependent degradation during maximum power point tracking
and find an increase in recombination resistance and a decrease in
capacitance for both subcells. Complementary optical and external
quantum efficiency measurements indicate that the main driver for
performance loss is the reduced capacity of the recombination layer
to facilitate recombination due to the formation of a charge extraction
barrier. This methodology highlights electrochemical impedance spectroscopy
as a powerful tool to provide critical feedback to unlock the full
potential of perovskite tandem solar cells