Twisted MoS ₂ Bilayers as Functional Elements in Memtransistors: Hysteresis, Optical Signatures, and Photocurrent Kinetics

ABSTRACT Layered 2D materials are considered as promising for memristive applications due to their ultimate vertical scalability compared to conventional semiconductor films and pronounced hysteresis properties. Bias‐resolved Raman and Photoluminescence mapping is used to quantify strain from phonon shifts and carrier density from the exciton‐trion balance while devices operate under electrical stress. Monolayer channels display strong gate control of carrier concentration and low hysteresis. In contrast, bilayer regions exhibit tensile strain with weaker carrier modulation. Twisted bilayers, especially at grain boundaries with monolayer domains, develop compressive strain and a widened excitonic gap that establishes a space‐charge region at the interface. This interfacial space charge correlates with enhanced electrical hysteresis and with a distinct optoelectronic signature: photocurrent follows with the largest superlinear exponents in twisted domains, sublinear response in conventional bilayers, and intermediate behavior in monolayers. The results provide a direct link between stacking disorder, local strain, charge redistribution, and device memory effects, and they supply a practical Bias‐resolved Raman and Photoluminescence mapping protocol and analysis workflow to map strain and doping in 2D FETs. These insights enable rational control of hysteresis for reliable logic and for engineered memtransistor functionality.