Flexoelectric Photocarrier Relaxations in Free‐Standing van der Waals CuInP 2 S 6

ABSTRACT Long‐term stable photocarriers in van der Waals ferroelectrics can be controlled without external electrical or thermal stimuli, providing a platform for versatile photonic functionalities. A comprehensive understanding and spatial controllability of photocarrier relaxation dynamics under nanoscale structural variation are required for the three‐dimensional vertical stacking of photonic circuits. Nevertheless, structurally correlated observation of interlayer relaxation dynamics and its device‐scale realization have been limited by the spatial resolution of conventional near‐field optics and by irreversible domain‐switching methods. Here, an extendable flexoelectric platform is presented, in which an axial nanogap structure is combined with time‐resolved optical‐pump/electrical‐probe microscopy. The platform, which operates through van der Waals flexoelectric domain reconstruction, enables tunable interlayer photocarrier relaxation and switchable polarizability of interlayer electron‐hole pairs during interlayer tunneling. With respect to the spatial domain distribution, the asymmetric nanosecond‐scale interlayer dynamics are resolved through the decay profile of interlayer electron‐hole pair generation, the tunneling current, and spatial fluorescence‐lifetime mapping. The extendable flexoelectric platform provides a geometric route toward versatile optical functionalities in condensed matter physics.