High Efficiency PPV-Based Polymer Light Emitting Diodes With Cs2CO3 Cathode

In this study the phenomena resulting from the combination of a hole-dominant PPV-based light emitting polymer with an efficient electron injection layer of Cs2CO3 in light emitting diodes has been investigated. As a result, diodes with about 35 % higher efficiency were achieved with an optimized PPV Cs2CO3 structure in comparison to the traditional PPV-Ba structure. Additionally to the increased efficiency, also the lifetime of the Cs2CO3-diodes is comparable to the Ba-diodes implying that the long-term stability of the diodes is not affected by the optimized Cs2CO3-cathode. In this study, the influence of the Cs2CO3 thickness on the electrical and optical properties before, during and after the electrical stressing of the diodes are discussed.