Low-voltage and high-stability p-type doped blue organic light-emitting diodes with bilayer hole-injection layers

摘要

In recent years, organic light-emitting diodes (OLEDs) for the application of flat-panel displays (FPDs) have been attracting many researchers due to their advantages such as excellent image quality, low weight, easy manufacturability, low cost, and large-area extendibility. Blue OLEDs are the potential light source to make full-color FPDs by a color-conversion method [ 1 -4]. However, due to a large energy bandgap of blue emission materials, blue OLEDs were widely reported to have relatively low luminance efficiencies and high operation voltage, compared to the devices with low energy emission wavelength [5-8]. Some studies have investigated the approaches to improving the performance for blue OLEDs, such as the use of a low-work function cathode [9, 10], a high-mobility electron-transport material [11], or a host-guest system as a light emitting layer (EML) [12-14].