Phosphorescent Host Research Articles

Formation of Crystalline SrAl2O4 Nanotubes by a Roll‐Up and Post‐Annealing Approach

On a roll: Nanotubes of SrAl2O4, an important phosphorescent host material, are prepared. Nanoscrolls are first formed through the roll-up of an artificial lamellar precursor in solution. The layer interfaces are then removed by high-temperature annealing, resulting in single-crystalline nanotubes.

Efficient organic light-emitting devices using an iridium complex as a phosphorescent host and a platinum complex as a red phosphorescent guest

We demonstrated efficient organic light-emitting devices (OLEDs) using a phosphorescent host/guest system consisting of bis(2-phenylpyridinato-N,C2′)iridium(acetylacetonate) [(ppy)2Ir(acac)] as a host and a platinum complex (Pt-SA-1) as a guest. The OLED using (ppy)2Ir(acac) film doped with Pt-SA-1 (1wt%) showed an ideal red emission via efficient energy transfer from the host to the guest. The external quantum efficiency of the device was as high as 8.3%. The driving voltage was significantly reduced compared with a device using a conventional host of 4,4′-di(carbazole-9-yl)biphenyl, which resulted from the enhancement of the hole injection from the hole-transport layer to the host.

Long-lasting phosphorescence in Mn2+:Zn2GeO4 crystallites precipitated in transparent GeO2–B2O3–ZnO glass-ceramics

Mn2+-doped GeO2–B2O3–ZnO (GBZ) glasses were investigated and developed as long-lasting phosphorescence host materials. Transparent glass-ceramics were obtained after heat-treated at the first crystallization temperature for 20 min. By X-ray diffraction measurement and SEM observation, it is clarified that Zn2GeO4 crystallites with a diameter of about 1 µm precipitate on the sample’s surface after heat-treatment. An orange long-lasting phosphorescence from Mn2+ was observed in the 25GeO2–25B2O3–50ZnO glass matrix, however,a stronger long-lasting green phosphorescence was observed in the phase of Zn2GeO4 crystallites. This phenomenon is considered to be due to the different ligand field environment surrounding Mn2+ ions in the glass and the glass-ceramics. A possible mechanism for the long-lasting phosphorescence in the Mn2+-doped glass was discussed.

Organic Light-emitting Devices Based on Phosphorescent Hosts and Dyes

Phosphorescent dyes may lead to more efficient electroluminescent devices, since triplets should be formed in a 3-fold excess compared to singlets. Efficient devices are presented here that have been constructed using phosphorescent dye–doped layers as both the electron transporting and emitting layer. Triplet energy transfer from the host Ir(ppy)3 to the red phosphorescent dopant PtOX (see Figure) was observed directly.

Organic Light-emitting Devices Based on Phosphorescent Hosts and Dyes

Organic Light-emitting Devices Based on Phosphorescent Hosts and Dyes