Influence of Blocking Interlayer in Blue Organic Light-Emitting Diodes with Different Thicknesses of Emitting Layer and Interlayer

A series of blue organic light-emitting diodes with electron or hole blocking interlayer are fabricated. Different structures of blocking interlayers can influence the position of the recombination zone due to the fact that they confine carriers in different ways. We find that the double hole blocking interlayer structure can balance carrier injection more effectively. Its power and current efficiency are more stable and the current efficiency value is 30.2 cd/A at 1000 cd/m^2. Decreasing the thicknesses of the emitting layer and interlayers is in favor of the power efficiency. The performance of the device is also affected by changing the interlayer position when we use hole and electron blocking material as interlayers simultaneously.