Light emission from an ambipolar semiconducting polymer field effect transistor: Analysis of the device physics

Light emitting field-effect transistors LEFETs were fabricated with a low work function metal calcium and a high work function metal gold as the source and drain electrodes. The gold electrode serves as the source for holes into the band and the drain for electrons from the * band; the calcium electrode serves as the source for electrons into the * band and the drain for holes from the band. For 65 V VG 103 V, the LEFET operates in the ambipolar regime. The emission zone has been spatially resolved as it is moved across the channel by sweeping the gate voltage using confocal microscopy; the full width at half maximum is 2 m. At the gate voltage extremes VG=0 or VG=150 V , the electron hole density extends all the way across the 16 m channel such that the electron hole accumulation layer functions as the cathode anode for a light-emitting diode, with opposite carrier injection by tunneling; i.e., the carrier densities are sufficiently high that the accumulation layer functions as a low resistance contact, implying near metallic transport. © 2007 American Institute of Physics. DOI: 10.1063/1.2752582