Transistors and logic circuits based on metal nanoparticles and ionic gradients

Abstract

Dynamic ionic gradients of counterions in films of metal nanoparticles functionalized with charged organic ligands can be used to create transistors that are capable of a 400-fold modulation of the electrical conductivity and can be used to construct logic gates and half-adder circuits. Transistors are typically based on inorganic or organic semiconductors. Metals have generally been considered unsuitable for such use because bulk metals screen electric fields and thus achieving electrically tunable conductivity is difficult. Alternatively, gradients of counterions in films of metal nanoparticles functionalized with charged organic ligands can be used to construct electronic devices, including resistors, diodes and sensors, but modulating the conductivity in these systems has also proven to be challenging. Here we show that transistors and logic circuits can be created from thin films of functionalized gold nanoparticles using dynamic ionic gradients established via an unconventional five-electrode configuration. The transistors are capable of a 400-fold modulation of electrical conductivity, and by combining with metal nanoparticle diodes and resistors, can be used to construct NOT, NAND and NOR logic gates, as well as a half-adder circuit. We also show that transistors deposited on flexible substrates continue to work when deformed and can withstand electrostatic discharges.