Liquid-phase deposited 2D SnS-SnS2 composite films for memristor and synapse emulation

Two-dimensional (2D) materials have drawn extensive interest for applications in thin-film electronics, optoelectronics, and sensing. Among them, tin disulfide (SnS 2 ) is particularly attractive owing to its low cost, environmental friendliness, and excellent chemical and thermal stability. Importantly, the synthesis and deposition strategies for 2D materials play a critical role in controlling sulfur vacancies, tuning crystal phase and morphology, and ultimately determining device performance. Here, we demonstrate a solution-processed memristor based on SnS-SnS 2 composite thin films fabricated by spin-coating followed by sequential thermal reduction. Partial conversion of SnS 2 into SnS produces a phase-engineered architecture, where vertically aligned SnS domains are embedded within the SnS 2 matrix. Optimizing the SnS/SnS 2 ratio enhances resistive switching (RS) characteristics and synaptic emulation. The improved device behavior is mainly attributed to the controlled generation and migration of sulfur vacancies, together with internal phase modulation enabled by the vertical stacking structure. This scalable, low-temperature strategy provides a promising route toward high-performance neuromorphic memory devices.