  Fundamental electronic processes such as charge-carrier transport and
recombination play a critical role in determining the efficiency of hybrid
perovskite solar cells. The presence of mobile ions complicates the development
of a clear understanding of these processes as the ions may introduce
exceptional phenomena such as hysteresis or giant dielectric constants. As a
result, the electronic landscape, including its interaction with mobile ions,
is difficult to access both experimentally and analytically. To address this
challenge, we applied a series of small perturbation techniques including
impedance spectroscopy (IS), intensity-modulated photocurrent spectroscopy
(IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) to planar
$\mathrm{MAPbI_3}$ perovskite solar cells. Our measurements indicate that both
electronic as well as ionic responses can be observed in all three methods and
assigned by literature comparison. The results reveal that the dominant
charge-carrier loss mechanism is surface recombination by limitation of the
quasi-Fermi level splitting. The interaction between mobile ions and the
electronic charge carriers leads to a shift of the apparent diode ideality
factor from 0.74 to 1.64 for increasing illumination intensity, despite the
recombination mechanism remaining unchanged.
