  We propose a highly efficient thermoelectric diode device built from the
coupling of a quantum dot with a normal or ferromagnetic electrode and a
superconducting reservoir. The current shows a strongly nonlinear behavior in
the forward direction (positive thermal gradients) while it almost vanishes in
the backward direction (negative thermal gradients). Our discussion is
supported by a gauge-invariant current-conserving transport theory accounting
for electron-electron interactions inside the dot. We find that the diode
behavior is greatly tuned with external gate potentials, Zeeman splittings or
lead magnetizations. Our results are thus relevant for the search of novel
thermoelectric devices with enhanced functionalities.
