Monolayer OLEDs Using LEPs

2 Monolayer Organic Light-Emitting Diodes (OLEDs) Using LEPs 

Upon application of an electric field to an OLED very little current flows until a threshold field is reached. Above this threshold value light is emitted from activated pixels due to the fast radiative decay ( 1 ns) of excitons formed by the recombination of a hole and an electron for voltages, V Fth- Current flows according to the relationship  

The external quantum efficiency, //ext of monolayer OLEDs, i.e. the number of photons actually seen by the observer, is related to the number of photons emitted for every electron injected and is usually low, e.g. 0.05% for the first OLEDs using PPV. The observed external efficiency, i/ext, is much lower than the internal efficiency, as given by the following relationship  

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