Room-temperature charge localization in ion-coupled bilayer transistors

Controlling the localization of mobile charges in solids enables the discovery of correlated physical phenomena, but applying it for the development of next-generation electronics requires achieving such control under practical conditions. In this study, we report room-temperature, switchable charge localization in high-quality bilayer transistors that comprise a monolayer of molecular crystal on top of a monolayer semiconductor. By using an ion gate, we selectively populated either localized molecular states or semiconductor band states, achieving complete localization from mobile charges at densities up to 3 × 10¹³ per square centimeter. This transition was energetically stabilized by the formation of coupled electron-ion dipoles, which could be tuned through Coulomb engineering. These properties further enabled single-band ambipolar transistor operation without substitutional dopants, demonstrating the potential of electron-ion correlations for practical electronic applications.