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.