  Recent studies have shown the potential for bipolar thermoelectricity in
superconducting tunnel junctions with asymmetric energy gaps. The
thermoelectric performance of these systems is significantly impacted by the
inverse proximity effects present in the normal-superconducting bilayer, which
is utilized to adjust the gap asymmetry in the junction. Here, we identify the
most effective bilayer configurations, and we find that directly
tunnel-coupling the normal metal side of the cold bilayer with the hot
superconductor is more advantageous compared to the scheme used in experiments.
By utilizing quasiclassical equations, we examined the nonlinear thermoelectric
junction performance as a function of the normal metal film thickness and the
quality of the normal-superconducting interface within the bilayer, thereby
determining the optimal design to observe and maximize this nonequilibrium
effect. Our results offer a roadmap to achieve improved thermoelectric
performance in superconducting tunnel junctions, with promising implications
for a number of applications.
