The rapid proliferation of flexible electronics necessitates the development of self-powered energy harvesting systems with continuous power output and sensing signal monitoring. In this study, inspired by transient voltage output (0.2 volts, 4 days) is proposed by replacing movable water droplets with “confined” moisture, harvested and locked by a hygroscopic polymeric gel with high sorption capacity and rapid sorption-desorption kinetics. Further analysis reveals the capacitive behavior of SEHSI, leading to excellent tactile sensing capabilities with high sensitivity and rapid responsiveness, and humidity and temperature response with robust cyclic stability for over 10,000 cycles. Such all-in-one powering and sensing platforms demonstrate promising application potential in self-powered human-machine interactions, including breath status monitoring, contactless motion detection, and braille detection. Our design establishes a promising approach to developing self-powered energy harvesting and sensing systems for human-machine interfaces.

Temperature‐dependent transport measurements are performed on the same set of chemical vapor deposition (CVD)‐grown WS₂ single‐ and bilayer devices before and after atomic layer deposition (ALD) of HfO₂. This isolates the influence of HfO₂ deposition on low‐temperature carrier transport and shows that carrier mobility is not charge impurity limited as commonly thought, but due to another important but commonly overlooked factor: interface roughness. This finding is corroborated by circular dichroic photoluminescence spectroscopy, X‐ray photoemission spectroscopy, cross‐sectional scanning transmission electron microscopy, carrier‐transport modeling, and density functional modeling. Finally, electrostatic gate‐defined quantum confinement is demonstrated using a scalable approach of large‐area CVD‐grown bilayer WS₂ and ALD‐grown HfO₂. The high dielectric constant and low leakage current enabled by HfO₂ allows an estimated quantum dot size as small as 58 nm. The ability to lithographically define increasingly smaller devices is especially important for transition metal dichalcogenides due to their large effective masses, and should pave the way toward their use in quantum information processing applications.

Excitons are key to the optoelectronic applications of van der Waals semiconductors, with the potential for versatile on-demand tuning of properties. Yet, their electrical manipulation remains challenging due to inherent charge neutrality and the additional loss channels induced by electrical doping. We demonstrate the dynamic electrical control of valley polarization in charged excitonic states of monolayer tungsten disulfide, achieving up to a 6-fold increase in the degree of circular polarization under off-resonant excitation. In contrast to the weak direct tuning of excitons typically observed using electrical gating, the charged exciton photoluminescence remains stable, even with increased scattering from electron doping. By exciting at the exciton resonances, we observed the reproducible nonmonotonic switching of the charged state population as the electron doping is varied under gate bias, indicating a resonant interplay between neutral and charged exciton states.