Hole injection efficiency from metals transport layers

As for a6T, Mg led to superior rectifying behaviour for ECnT thin films, whereas the electroluminescence yields are not enhanced for lower workfunction electrodes [313], The latter unexpected effect could be due to different indiflusion of the metals or chemical reactions at the interface, as discussed in Section 6.1. From asymmetric cells comprising two different ECnTs it can be concluded that electroluminescence always takes place in the layer at the electron-injecting electrode. Thus the hole-injection and transport seems to be more efficient if compared with the electron transfer. The majority charge carriers are therefore holes injected at the ITO electrode. 

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