I am currently doing some research on organic light emitting diodes and am just trying to get my head around some of the terminology and concepts because I am more from the organic chemistry side don't have a strong material sciences/physics background.
My reading indicates that the work function is the amount of energy required to extract an electron from a material. Electrons are injected via the cathode and electrons are extracted from the anode (i.e hole injection)
I keep reading that for OLEDs, the cathode should have a low work function to match the energy of the LUMO of the electroluminescent layer, and the anode should have a high work function to match the HOMO. I've read this in many journals and review papers but none of them explain why.
Any help would be appreciated.