Gate-Tunable Ionothermoelectric Cooling in a Solid-State Nanopore.

Efficient heat dissipation at the nanoscale remains a major challenge for high-performance microelectronics. Here, we demonstrate a proof-of-concept approach for ionothermoelectric cooling, the ionic analogue of the Peltier effect, using gate-tunable solid-state nanopores integrated with nanoscale thermocouples. By integrating a nanoscale thermocouple directly adjacent to a gate-tunable solid-state nanopore, we quantitatively map local thermal responses driven by voltage-induced ion transport. We show that ionic heating scales with input power and varies with the ion species, revealing a dependence on the intrinsic heat of transport. Under salt concentration gradients, we observe ionic cooling, a fluidic analogue of the Peltier effect, arising from directional cation transport through negatively charged nanopores. This effect is further enhanced via electrostatic gating, which modulates the pore wall surface potential to tune the permselectivity. Under optimal gating, the system exhibits reversible transitions between heating and cooling regimes with temperature drops exceeding 2 K. Although modest compared to electronic Peltier devices, this effect establishes a viable mechanism for active, electrically tunable thermal management in nanofluidic systems. Given that water-based flow cooling already outperforms solid-state thermoelectrics by orders of magnitude, incorporating ionothermoelectric cooling can further enhance heat-pumping efficiency in micro- and nanofluidic architectures, thereby establishing a scalable on-chip ionic refrigeration strategy for next-generation semiconductor thermal control.