Emitting Electrochemical Cells

In 1995, a new device, whose structure was similar to that of a conventional LED, but whose active layer was composed of a 

In spite of the similarity with a conventional inorganic p-n junction, in the LECs, particularly for large-bandgap materials, mobile charges are almost exclusively injected from the electrodes (electrochemical doping). In the conventional inorganic p-n junction, mobile charges are already present in the bulk, prior to contact with the electrodes [245]. 

Using a bilayer polymer structure composed of PPV and MEH-PPV, two-color LECs were demonstrated [246]. When these devices are biased in one polarity, the voltage induced p-n junction is completely inside the PPV layer and the device emits green light characteristic of PPV. When biased at the opposite polarity, the p-n junction is completely inside the MEH-PPV layer and the LEC emits orange light characteristic of MEH-PPV. 

---

The working principle of the polymer light-emitting electrochemical cell is shown in Figure 9-23 ... 

Q Pei, G Yu, C Zhang, Y Yang, and AJ Heeger, Polymer light-emitting electrochemical cells, Science, 269 1086-1088, 1995. 

Y Cao, G Yu, AJ Heeger, and CY Yang, Efficient, fast response light-emitting electrochemical cells electroluminescent and solid electrolyte polymers with interpenetrating network morphology, Appl. Phys. Lett., 68 3218-3220, 1996. 

Y Cao, MR Andersson, Q Pei, G Yu, and AJ Heeger, Light-emitting electrochemical cells using crown ether as solid electrolyte, J. Electrochem. Soc., 144 L317-L320, 1997. 

G Yu, Y Cao, C Zhang, Y Li, J Gao, and AJ Heeger, Complex admittance measurements of polymer light-emitting electrochemical cells ionic and electronic contributions, Appl. Phys. Lett., 73 111-113, 1998. 

G. Yu, Polymer Light-Emitting Electrochemical Cells in Surface Cell Configuration, U.S. Patent... 

T. Johansson, W. Mammo, M.R. Andersson, and O. Inganas, Light-emitting electrochemical cells from oligo(ethylene oxidej-substituted polythiophenes evidence for in situ doping, Chem. Mater., 11 3133-3139, 1999. 

Y. Yang and Q. Pei, Light-emitting electrochemical cells from a blend of p- and n-type luminescent conjugated polymers, Appl. Phys. I ett., 70 1926-1928, 1997. 

FC Chen, Y Yang, and Q Pei, Phosphorescent light-emitting electrochemical cell, Appl. Phys. Lett., 81 4278-4280, 2002. 

Figure 16.6 Schematic picture of a solid-state light-emitting electrochemical cell. (See the color version of this figure in Color Plates section.)...

Figure 16.6 Schematic picture of a solid-state light-emitting electrochemical cell.

Light-emitting electrochemical cells, and OLEDs, 12, 175 Light-emitting molecules, by G-H bond activation, 10, 244 Light propagation, and second-order non-linear polarization, 12, 104... 

Monochromatic organic light-emitting diodes light-emitting electrochemical cells, 12, 175 with organometallic emitters, 12, 158 Monocyclic arenes, in Ru and Os compounds, 6, 466 Mono(cyclooctatetraenyl) actinide(IV) compounds, preparation, 4, 227... 

---