We analyzed the structure of buried interface of BBDMS PPV/ITO system using a high resolution ADXPS technique. A transitional layer structure, whose chemical composition, state and valence band changed gradually from BBDMS PPV surface of film to substrate ITO, was observed. It was found that O 2- ion from ITO diffused into polymer film, interacted with back bone carbon and formed the carbonyl bonding which could possibly constructed the channel of the carrier on the heterointerface. Indium of ITO also diffused into BBDMS PPV layer and In(OH) 3 was formed during diffusion. The diffusion and reaction between PPV/ITO interface may affect the performance of PLED significantly.
