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.