We predict a novel type of excitonñphonon bound state, namely, interlayer polaron, in a two-layer two-dimensional semiconductor system. The interaction of the interlayer exciton with the soft out-of-plane lattice vibrations gives rise to a bound quasiparticle [1]. We identify the weak and strong excitonñphonon coupling regimes and calculate the polaron energy and its effective mass. We study interplay of the flexural rigidity and tension of the layers in the polaron formation and discuss the effects of anharmonicity.

[1] M. A. Semina, M. M. Glazov, E. Sherman, Interlayer ExcitonñPolaron in Atomically Thin Semiconductors, Ann. Phys. (Berlin), 2000339 (2020)