p-bPPhenB is a phenanthroline based electron transport layer materials for organic light-emitting diodes (OLEDs). p-bPPhenB exhibits very high electron mobility of 5.8 × 10−3 cm2 V−1 s−1, an order higher than that of Bphen (5.5 × 10−4 cm2 V−1 s−1), creating a very small injection barrier at the p−n junction interface. Single-stack red phosphorescent OLED (PhOLED) with p-bPPhenB as the electron transport layer demonstrates a low driving voltage of 2.7 V and a significantly improved maximum power efficiency of 56.8 lm W−1, an external quantum efficiency of 30.8% with a device lifetime of LT95 = 130 h.
Sandwich structured semi-transparent cathode fabricated by inserting a thin silver (Ag) layer between two layers of p-bPPhenB which acts as both wetting inducer and capping layer, shows excellent optical and electrical properties with high transmittance of 83.8% and low absorbance of 7.65% at 550 nm, and low sheet resistance of 2.1 Ω/sq. p-bPPhenB stabilizes of surface properties of the thin Ag film by forming coordination bond between the Ag atoms and nitrogen atoms of p-bPPhenB through donating unshared electrons to the Ag atom. Optimized phosphorescent green top-emission OLED with this pure Ag cathode configuration enables a low driving voltage of 5.0 V at 10 mA cm-2 and high maximum current efficiency of about 167 cd/A.
Also, p-bPPhenB can also work with HATCN to fabricate a sandwich structure of Ag semi-transparent cathode: p-bPPhenB (40 nm)/Ag (12 nm)/HATCN (40 nm).