Sliding-Ferroelectric hBN Bilayer Controlled Carrier Lifetimes in TMD Heterostructures

Sliding ferroelectricity in bilayer hexagonal boron nitride (hBN) provides an atomically sharp, nonvolatile knob for engineering interfacial polarization in van der Waals heterostructures. Here, we combine time-dependent density functional theory with nonadiabatic molecular dynamics to study how stacking-dependent ferroelectric polarization in bilayer hBN can be used to tune charge redistribution, electron-phonon coupling, and nonradiative carrier recombination in MoSe₂/hBN and WSe₂/hBN heterostructures. Switching the bilayer hBN stacking between nonpolar AA' and ferroelectric AB/BA reverses the interfacial potential step and charge-transfer direction, which modulates the nonadiabatic coupling, electronic decoherence, and recombination kinetics. As a result, carrier lifetimes can be tuned over more than one order of magnitude, from 1.46 to 74.6 ns, by choosing the stacking sequence and TMD species. Fourier analysis of band-gap fluctuations identifies mode-selective phonon coupling: long-lived configurations are associated with spectra dominated by low-frequency interlayer shear and breathing modes, whereas short-lived ones show enhanced contributions from intralayer optical phonons of A₁', A₂″, and E' symmetry that more efficiently modulate the band edges. These results establish sliding-ferroelectric proximity engineering as an effective strategy for programming interfacial charge dynamics in 2D heterostructures and provide microscopic design rules for reconfigurable ferroelectric semiconductor platforms for future optoelectronic and information devices.