Polymer light emitting field effect transistors with steadily high efficiency over three orders of magnitude of current*

To simultaneously achieve efficient and intensified optical output is the most challenging task for polymeric light emitting field effect transistors (PLEFETs). A p-type unipolar PLEFET with high brightness but oversaturated holes will limit recombination efficiency. Instead, an ambipolar PLEFET with high recombination current will decrease on/off ratio. An ideal solution will be the combined advantages of both LEFETs, significant on/off ratio, high current density, and efficient recombination. A bilayer PLEFET can meet the three criteria satisfactorily by applying asymmetric organic/inorganic-hybrid transparent contacts. Hole/electron injections and photon output in a p-type PLEFETs was simultaneously improved. For source-drain current over 3 orders of magnitude from sub-micro ampere to sub-mini ampere, corresponding to 26 to 3747 cd/m², external quantum efficiency (EQE) steadily sustained 0.5%. EQE of the PLEFETs in this work was enhanced remarkably, 0.5% vs. < 0.08% (conventional ones), and on/off ratio remained high at 10⁴-10⁵. Asymmetric organic/inorganic-hybrid transparent contacts demonstrated a promising strategy for energy-efficient PLEFETs.