Fabrication of a blue organic light-emitting diode with a novel thermal deposition boat

摘要

A highly efficient blue phosphorescent organic light emitting diode (PhOLED) is fabricated by using a novel thermal deposition boat. The boat has two unique features: indirect deposition rate control and fast rate response. With these features, a compact combinatorial evaporation source module is constructed, which utilizes only limited space and enables the fabrication of OLED devices of complex architectures. The deposition rate using this newly designed boat can be controlled within 5% accuracy and the rate response is sufficiently fast that it is particularly useful for producing emitting layers with a linearly graded composition. Two blue PhOLED devices with different architecture in the emitting layer are fabricated with the new boat. The device with a linearly graded mixed host shows higher efficiency than the device with a uniformly mixed one, indicating the advantage of gradual interface change.