Research On Stability Of Organic Electroluminescent Devices

OLED ( organic electroluminescent diodes ) is one of the most promising next-generation flat panel display technology due to its outstanding advantages ,such as high efficiency , flexible ,and low voltage .And much progress has been made in the researches on the materials and device structure in the last decade. Stability among all the properties, which limits the application of OLED , has been a primary subject among the researches on OLED. If the degradation and other problems such as efficiency .luminance is overcomed, OLED will be put into use widely . The problem of degradation has been concerned widely .Double-layer organic electroluminescent diodes composed of a spin-coated PVDF/TPD and a vacuum-sublimed Alq3 layer were prepared. The purpose of introducing ferroelectric polymeric PVDF material was to make use of the remanent polarization of ferroelectric materials and to study the effect of the internal field formed in the device during the device worked . The diodes were driven at constant voltage and were also kept under short-circuit or reverse-bias conditions. Observations of 'uminance-current density-voltage relations at constant voltage driving were repeated. The decrease of both luminance and current density during constant voltage driving was observed. Both spontaneous and reverse-bias assisted recoveries of device performances were observed, and these degradation and recover}' phenomena were discussed in terms of the movement of ionic impurities and the formation of permanent and induced electric field dipoles in organic layers. The results presented the degradation of the device is recoverable to some extent. Some promising results has been given in the paper.