  Charge redistribution at interfaces is crucial for electronic applications of
high-Tc superconductors, since the band structure is modified on a local scale.
We address the normal-state electronic structure of YBa2Cu3O7 (YBCO) at an
YBCO-metal contact by first principles calculations for prototypical interface
configurations. We derive quantitative results for the intrinsic doping of the
superconducting CuO2 planes due to the metal contact. Our findings can be
explained in terms of a band-bending mechanism, complemented by local screening
effects. We determine a net charge transfer of 0.09 to 0.13 electrons in favour
of the intraplane Cu sites, depending on the interface orientation.

Superconductivity