Fullerene-based polymer grid triodes

We report the fabrication of polymer grid triodes (PGTs) using C-60 as the semiconducting medium. The structure, a self-assembling porous conducting polyaniline network placed between two semiconducting layers of C-60, and sandwiched between two metal electrodes, demonstrates the I-V characteristics of a three terminal device in which the current is controlled by the grid potential. As a result of the higher mobilities of the fullerenes compared to those of conjugated polymers, the fullerene devices offer some performance advantages; the operating voltages are less than 5 V with current densities exceeding 1 mA/cm(2). By fabricating devices with different grid densities, it is shown that the grid exhibits a strong influence on the I-V characteristics for high grid densities, and a correspondingly low influence for low densities, in agreement with theory. The I-V characteristics of the C-60 PGTs are well described by an effective diode model, similar to that used for vacuum triodes. (C) 1997 American Institute of Physics.