A highly efficient red electrophosphorescent device exhibited saturated red emission and an impressive external quantum efficiency [eta(ext) = 10.8% (ph/el)] with simple device configuration of doping an iridium complex (Mpq(2)Iracac) into a novel ambipolar spiro-configured donor-acceptor host material (D2ACN) has been developed.
We have prepared a highly efficient non-doped green organic light-emitting diode (OLED) incorporating a novel 9,9-diarylfluorene-terminated 2,1,3-benzothiadiazole green emitter (DFBTA), which exhibits an excellent solid state photoluminescence quantum yield (81%), and new triaryldiamines (DPAInT2, DPAInF) with high hole mobility derived from rigid and coplanar cores. The optimal device: ITO/DPAInT2/DPAInF/TCTA/DFBTA/Alq3/LiF/Al displayed impressive device characteristics, including a maximum external quantum efficiency (h ext ) of 3.7% (12.9 cd A À1 ) and a maximum brightness at 168 000 cd m À2 .
In this work, we report the low-temperature phase transition of sodium niobate (NaNbO 3 ) ceramics at the antiferroelectric-ferroelectric phase studied by the Raman scattering technique over the temperature range 10-300 K. The spectral shape indicates that the phase transition occurs at 160 K on the cooling cycle and at 260 K on heating. The recorded spectra are discussed following the separation of modes into the internal stretching modes of the NbO 6 octahedron and Na + cation translational modes. The 62 and 75 cm −1 peaks are proposed as the translational modes of Na + cation against the NbO 6 octahedron.
A bifluorene analogue, T2N, containing a pyridyl moiety serves as both a host and an efficient electron-transporting material that is compatible with various heavy metal-containing red (Ir, Ru, Os, and Pt) and green (Ir) phosphors for highly efficient phosphorescent OLEDs possessing simple device architectures.
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