Low Voltage Polymer Transistors

The combination of polymer semiconducting 'inks' and relatively high resolution printing processes promises to make integrated printed circuits commercially viable. These circuits can be flexible and capital costs of production are very low. One of the key challenges to implementation of this technology is that most transistors made using polymer semiconductors have high operating voltages, which is not ideal for low power, low cost, battery compatible technology. We report on an organic metal semiconductor field effect transistor which operates at 3.5 V. In the initial implementation of this transistor poly(3-hexylthiophene) is the semiconductor, with an aluminium layer used as the gate electrode. The on/off current ratio of this device is only 24.6, but simulations suggest that an improvement of up to three orders of magnitude is possible. The fabrication process requires one less step than other organic transistors. It also uses the gate to encapsulate the transistor, limiting exposure oxygen and moisture, which are known to degrade their performance.