Molecular Sieve Promoted Growth of Ferroelectric Trilayer 3R‐MoS ₂ for Polarization‐Dependent Reconfigurable Optoelectronic Synapses

ABSTRACT 2D sliding ferroelectric semiconductors are a unique combination of switchable electric polarization and gate/light modulated charge transport, rendering them an appealing platform for multifunctional electronic and optoelectronic devices. However, the currently available 2D sliding ferroelectric semiconductors are limited, and the coupled gate‐light‐polarization interactions in such systems remain to be further explored. Herein, trilayer (3L) rhombohedral‐stacked (3R) MoS ₂ nanoflakes are synthesized via a molecular sieve‐assisted chemical vapor deposition strategy, in which the combined physical vapor buffer and chemical sodium release from the molecular sieves effectively promote vertical growth with a favorable 3R stacking configuration. The noncentrosymmetric crystal structure, switchable out‐of‐plane polarization, and robust sliding ferroelectricity are systematically characterized. Integrating 3L 3R‐MoS ₂ into ferroelectric semiconductor field‐effect transistors (FeS‐FETs) reveals a large polarization‐direction‐dependent memory window of 13.8–14.6 V. Moreover, the ferroelectric polarization state, reversibly controlled by the polarity of the gate voltage, strongly governs the temporal photoresponse, enabling reconfigurable progressive photocurrent depression or facilitation. Combined with its narrow bandgap and defect‐assisted absorption, a broadband optoelectronic synaptic plasticity was further evaluated under a specific polarization state. These results establish 3L 3R‐MoS ₂ as a highly promising 2D crystals for ferroelectric optoelectronic synapses and future in‐memory sensing systems.