**4. Conclusions**

Currently, the commerical application of organic lighting is being held back by the fact that the power efficiency of OLEDs drops drastically with the increase in active area.This means that the luminous flux of OLEDs does not increase automatically if the emissive area is increased. Thus, it becomes the top priority to develop the charge injection techniques which can increase the power and emittance of OLEDs. The charge injection techniques discussed in this chapter are still in their very early stages, and their further development depends mostly by inventing new materials which can meet all the requirements listed above.
