All-organic bipolar vertical transistor with sulfonated polyaniline base energy barriers favoring recombination emitter-collector current

Abstract We report the development and characterization of an all-organic vertical transistor, with tris(8-hydroxyquinoline) aluminum (Alq3) as emitter, poly(bithiophene) (PBT), as collector material and a sulfonated polyaniline (SPAN) layer as base material in the structure Au/PBT/SPAN/Alq3/CsO/Al. A thin cesium oxide (CsO) layer provides improved electron injection from the Al into the Alq3. The transistor is operated in the usual common-emitter mode were the output characteristic evidences the modulation of the collector current through the applied voltage, showing common-emitter gain of 160 at 4.5 V. The incremented gain is due to an increased recombination current, consequence of the arrangement of the frontier orbitals of PBT, SPAN and Alq3, which favors the confinement of electrons and holes in the SPAN layer.