Amplification of electrical signals with molecule-based transistors: power amplification up to a kilohertz frequency and factors limiting higher frequency operation

Polyaniline- and poly(3-methylthiophene)-based transistors are demonstrated to amplify electrical signals at frequencies exceeding 100 Hz. The amplification of sinusoidal signals to the gate is established by showing the ratio of the average power in the drain circuit to that in the gate circuit exceeds unity. For the devices measured the amplification factor falls to unity between 100 and 1000 Hz. Measurements have been carried out at 298K for the microelectrochemical transistors immersed in aqueous or non-aqueous electrolyte solutions. The transistors consist of a pair of Au (or Pt) microelectrodes (approx. micron long x approx 2 micron wide x approx 0.1 micron high) connected by the redox polymer. The two microelectrodes serve as source and drain and the polymer serves as the channel of the device.