Light-emitting diodes based on high electron affinity polymer Langmuir-Blodgett films

To balance the electron injection and the hole injection and to improve the efficiency in polymer light-emitting diode (LED) by using air-stable electrode such as aluminum, we used high electron affinity polymer, alkoxyl-substituted poly(cyanoterephthalylidene) (C-16-CNPPV), as the emission layer. The polymer can form stable condensed film at air-water interface, its limiting repeating unit area obtained from the pi-A isotherm is close to the theoretical area calculated by Corey-Pauling-Koltun molecule model, and the transfer ratios were 0.7 similar to 0.8. LEDs with configuration of ITO/PPV/C-16-CNPPV LB films/Al was fabricated. The I-V curve reveals typical diode characteristics with rectification ratio of 10(3). The uniform visible emitting light can be clearly seen in a dark room at low driving voltage.