In the past decade, halide perovskite (HaP)-based solar cells (PSC) demonstrated a remarkable breakthrough in photovoltaic performance with power conversion efficiencies exceeding 25%. HaPs mark an outstanding class of materials for photon absorption but are prone to degradation due to their hybrid organic inorganic character and hence volatile chemical components and reactive halide ions. While HaPs exhibit a pronounced defect tolerance and self-healing such that the electronic properties do not change considerably with the formation of defects, film degradation will eventually deteriorate the optoelectronic properties. A key strategy to substantially enhance the stability of these compounds is to modify the interfaces and thereby control the chemistry and driving force for ion migration in the perovskite film. My talk will focus on the means and developments to analyze and tailor interfaces in HaP based semiconductor devices to gain control over the electronic properties at the nanoscale and electronic coupling to adjacent functional layers. On the one hand, the device characteristics can be affected by the alignment of the frontier molecular orbitals of an organic charge transport layers (CTL) with the electronic transport level in the perovskite. On the other hand, the doping type of the substrate underneath can template the doping type of subsequently deposited HaP films. In our studies we elucidated these mechanisms by examining a selection of charge transport layers adjacent to the perovskite film.