In this work, we investigated a series of terpyridine-based derivatives, referred to as TerPyB derivatives, as an electron-transporter for highly effient phosphorescent OLEDs. In this series of derivatives, we focused on intra- and/or intermolecular CH/N weak hydrogen bonds interaction for high molecular orientation leading to high electron-mobility. TerPyB derivatives have been found to have a deep lowest unoccupied molecular orbital (LUMO) (Ea = 3.0-3.6 eV) and a highest occupied molecular orbital (HOMO) (Ip = 6.5-7.0 eV) energy level compared to conventional electron transport material. The thermal properties of 2-TerPyB were estimated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The glass transition temperature (Tg) was observed at 162 ˚C indicating morphological stability. The weight loss of 5% (Td5) was observed around 420˚C, indicating the thermal stability. Then, we employed 2-TerPyB as a electron transport layer (ETL) for fac-tris (2-phenylpyridine) iridium(III) [Ir(ppy)3], a well-known green phosphorescent emitter. The device structure is [ITO (130nm)/poly(arylene ether ketone)-containg triphenylamine (TPAPEK): 4-isopropyl-4’-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate (PPBI) (20 nm)/TAPC (30 nm)/Ir(ppy)3 8 wt% doped CBP (10 nm)/ ETL (50 nm)/LiF (0.5 nm)/Al (100 nm)]. We used 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI) as a reference. The device showed reasonably low operation voltage of 2.62 V at 1cd m-2, which is 0.16 V lower than that of the device with TPBI. And at 100 cd m-2, a high power efficiency of 78.4 lm W-1 and a high external quantum efficiencies of 21.2 % were realized at the same time.