  Optimizing selective contact layers in photovoltaics is necessary to yield
high performing stable devices. However, this has been difficult for
perovskites due to their complex interfacial defects that affect carrier
concentrations in the active layer as well as charge transfer and recombination
at the interface. Using vacuum thermally-evaporated tin oxide as a case study,
we highlight electrochemical tests that are simple yet screen device-relevant
contact layer properties, making them useful for process development and
quality control. Specifically, we show that cyclic voltammetry and
potentiostatic chronoamperometry correlate to key performance parameters in
completed devices as well as other material/interfacial properties relevant to
devices such as shunt pathways and chemical composition. Having fast, reliable,
scalable, and actionable probes of electronic properties is increasingly
important as halide perovskite photovoltaics approach their theoretical limits
and scale to large-area devices.
