Reprogrammable Carrier Lifetimes in 2D Materials via Ultrafast Ferroelectric Switching

Carrier lifetime is a critical parameter in advancing the efficiency and functionality of optoelectronic devices, yet conventional materials provide limited opportunities for dynamic and reversible control. Sliding ferroelectricity in two-dimensional van der Waals materials offers a route to actively modulating electronic properties through interlayer translation. Using ab initio nonadiabatic molecular dynamics simulations on bilayer boron nitride (BN) and tungsten diselenide (WSe₂), we demonstrate how spontaneous polarization in sliding ferroelectrics governs carrier recombination. Polarization drives interlayer separation of frontier states, suppressing electron-hole wave function overlap and prolonging lifetimes relative to nonpolar stackings, with the strongest effects in systems whose electronic structure favors interlayer localization. Remarkably, defects in sliding ferroelectrics exhibit bidirectional tunability of carrier lifetimes. Using nitrogen vacancy in BN and selenium vacancy in WSe₂ as the prototypical systems, we show that polarization switching can either extend carrier lifetimes or accelerate recombination, providing reversible, on-demand control. We further propose and validate a practical pathway to achieve this control: a synergistic combination of photoexcitation and a modest electric field that enables deterministic, ultrafast polarization reversal. This strategy transforms static traps into adaptive elements, allowing a single material to be optimized on-the-fly for conflicting device requirements. Our findings pave the way for multifunctional optoelectronics where carrier dynamics can be actively reprogrammed to satisfy changing operational demands.