  Heterostructures of two-dimensional transition metal dichalcogenides (TMDs)
are emerging as a promising platform for investigating exotic correlated states
of matter. Here, we propose to engineer Bose-Fermi mixtures in these systems by
coupling inter-layer excitons to doped charges in a trilayer structure. Their
interactions are determined by the inter-layer trion, whose spin-selective
nature allows excitons to mediate an attractive interaction between charge
carriers of only one spin species. Remarkably, we find that this causes the
system to become unstable to topological p+ip superconductivity at low
temperatures. We then demonstrate a general mechanism to develop and control
this unconventional state by tuning the trion binding energy using a
solid-state Feshbach resonance.
