Gate-Tunable Electron Injection Based Organic Light-Emitting Diodes for Low-Cost and Low-Voltage Active Matrix Displays

Low-cost and low-voltage active matrix displays were fabricated by simply patterning gate electrode arrays on a polymer electrolyte (PE)-coated polymer light-emitting diode (PLED). Structurally, a PE capacitor seamlessly stacked on a PLED by sharing a common Al:LiF composite electrode (PEC|PLED). This monolithic integrated organic optoelectronic device was characterized and interpreted as the tunable work function (surface potential) because of the perturbation of accumulated ions on Al:LiF composite electrode by PEC charging and discharging. The modulation of electron injection by the PEC resulted in increases in the electroluminescent brightness, from <100 cd m^–2 to >8000 cd m^–2, and the external quantum efficiency from <0.025% to 2.4%

Electrolyte-Gated Red, Green, and Blue Organic Light-Emitting Diodes

We report vertical electrolyte-gated red, green, and blue phosphorescent small-molecule organic light-emitting diodes (OLED), in which light emission was modified by tuning the electron injection via electrochemical doping of the electron injection layer 4,4-bis­(<i>N</i>-carbazolyl)-1,1-biphenyl (CBP) under the assistance of a polymer electrolyte. These devices comprise an electrolyte capacitor on the top of a conventional OLED, with the interfacial contact between the electrolyte and electron injection layer CBP of OLEDs achieved through a porous cathode. These phosphorescent OLEDs exhibit the tunable luminance between 0.1 and 10 000 cd m^–2, controlled by an applied bias at the gate electrode. This simple device architecture with gate-modulated luminance provides an innovative way for full-color OLED displays