Vertical Quantum Dot Electrochemical Transistors and Complementary Inverters.

Quantum dot (QD) films possess intrinsic free volumes that can be charged volumetrically with electrolytes, enabling modulation of charge density via electrochemical doping-a fundamental mechanism of electrochemical transistors (ECTs). In this work, it is reported the first demonstration of vertical QD electrochemical transistors (vQECTs), in which an n-type InAs QD channel is stacked vertically between the source/drain electrodes. This architecture significantly reduces the channel length to the tens of nanometer scale, offering a promising strategy to enhance device transconductance. The resulting n-type vQECTs exhibit a high transconductance of 20.96 (±2.16) mS and a high integration area normalized on-current of 79.5 (±3.54) A cm⁻ along with excellent operational stability (including endurance against bias stress, storage, and repeated on/off cycling operation). These results demonstrate performance comparable to typical p-type vertical organic ECTs (vOECTs), suggesting that vQECTs can serve as a complementary counterpart to existing vOECTs. To illustrate this, n-type vQECTs are further integrated with p-type vOECTs to construct vertically stacked complementary inverters, achieving a signal gain of ≈4.7.