  Mobile ions in hybrid perovskite semiconductors introduce a new degree of
freedom to electronic devices suggesting applications beyond photovoltaics. An
intuitive device model describing the interplay between ionic and electronic
charge transfer is needed to unlock the full potential of the technology. We
describe the perovskite-contact interfaces as transistors which couple ionic
charge redistribution to energetic barriers controlling electronic injection
and recombination. This reveals an amplification factor between the out of
phase electronic current and the ionic current. Our findings suggest a strategy
to design thin film electronic components with large, tuneable, capacitor-like
and inductor-like characteristics. The resulting simple equivalent circuit
model, which we verified with time-dependent drift-diffusion simulations of
measured impedance spectra, allows a general description and interpretation of
perovskite solar cell behaviour.
