Solid-state Thermometry Via Ionic–electronic Coupling in Two-Dimensional Heterostructures

The coupling of ionic and electronic transport in solid-state systems offers new opportunities for realizing compact, energy-efficient sensing technologies, yet practical implementations remain limited. Here we introduce a two-dimensional iontronic platform based on field-effect transistors that integrate monolayer MoS2 channels with van der Waals bimetallic thiophosphates (ABP2X6, A = Li, Cu, Ag and so on; B = In, Sc and so on; and X = S and Se) as ionic gate dielectrics to realize on-chip thermometry. Specifically, we exploit thermally activated ion migration within the gate dielectric leading to conductance modulation in the MoS2 channel for temperature sensing. We achieve ~1–2 °C resolution, fast electronic readout and subpicojoule energy consumption in an ultracompact footprint (~1 µm2). Beyond thermometry, these results establish bimetallic thiophosphates as a versatile platform for solid-state iontronics and broaden the functional design space of van der Waals heterostructures for sensing, actuation and adaptive electronics. Thermally activated ion migration in van der Waals heterostructures delivers precise, energy-efficient on-chip thermometry.