Integrated, high-mobility polymer field-effect transistors driving polymer light-emitting diodes

An improved poly-hexylthiophene (P3HT) polymer field-effect transistor with field-effect mobility of 0.05-0.1 cm2/Vs and ON-OFF current ratio of 106–108 is demonstrated. The high ON-OFF ratio is obtained by careful device processing in N2 atmosphere and use of a reducing surface capping layer. The device has sufficient post-processing robustness that it can be integrated without degradation into a simple multilayer optoelectronic device in which the FET supplies the current to a polymer LED. For comparable size of FET and LED the FET supplies a current density of 10 mA/cm2 to the LED resulting in a brightness in excess of 100 Cd/m2. The FET-LED device is a step towards optoelectronic integrated circuits such as all-polymer active-matrix LED displays.