Since negative differential resistance phenomenon of the dye-doping polymer thin films was discovered

the mechanism of negative differential resistance has not been well explained due to many affecting factors. Several different interpretations were put forward

but most of them lacked the experimental evidence. In this paper the factors affecting negative differential resistance of the dye-doping polymer thin film devices was studied

and experimental evidence brought forward in order to further interpret the principle of organic negative differential resistance. Many kinds of dye-doping polymer thin films devices were fabricated. Factors affecting negative resistance including different organic dyes and polymeric matrices

varied composition and thickness of the film

ITO and anodic polyaniline were investigated respectively. In an atmosphere

a remarkable negative resistance phenomenon was found in low voltage state (3～4V) at room temperature. The maximum ratio of peak current to valley current was approximately 8. The appearance of the negative differential resistance phenomenon and the magnitude of ratio of peak current to valley current depended on thickness of the film

structure and fabrication technique of the device. When negative differential resistance was big enough

the electrical current flowing past the negative differential device would be small hence the peak of electrical current would be concealed. An equivalent circuit model composed of a diode in parallel with a negative resistance device was put forward in order to interpret negative differential resistance phenomenon. The negative differential resistance appeared to be caused by an imblanced injection of charge carriers. A novel soluble PPV derivative containing oxadiazole electron transporting group on the main chain (OPPV) was designed and synthesized

which had the abilities of hole and electron transmissions. The device showed stable N-type negative differential resistance characteristics in the atmosphere. Compared to inorganic negative differential resistance device

organic negative differential resistance device has many advantages such as easier fabrication as well as lower cost. If related materials and technologic conditions could be controlled

the negative differential resistance phenomenon would be observed distinctly and it is possible to develop a novel organic negative differential resistance device.