Trilayer structure

Trilayer structures offer the additional possibility of selecting the emissive material, independent of its transport properties. In the case of small molecules, the emitter is typically added as a dopant in either the HTL or the ETL, near the interface between them, and preferably on the side where recombination occurs (see Fig. 13-1 c). The dopant is selected to have an cxciton energy less than that of its host, and a high luminescent yield. Its concentration is optimized to ensure exciton capture, while minimizing concentration quenching. As before, the details of recombination and emission depend on the energetics of all the materials. The dopant may act as an electron or hole trap, or both, in its host. Titus, for example, an electron trap in the ETL will capture and hold an election until a hole is injected nearby from the HTL. In this case, the dopant is the recombination mmo.-... 

Spin-dependent scattering, interlayer coupling, and tunnel magnetoresistance in trilayer structures... 

Fig. 31. Hall resistance / Hall (circles) and sheet resistance / sheci (triangles) versus magnetic field B at 25 K for a (Gao.95Mno.os)As/(Alo. i4Gao.86)As/(Gao.97Miio.o3)As trilayer structure. Closed and open symbols show the major and minor loops, respectively. Dashed arrows indicate sweep directions of the magnetic field. The minor loop of f Hail is skewed by the presence of a ferromagnetic coupling between the two (Ga,Mn)As layers (Chiba...

Tellurium, which has low thermal diffusivity, can be used in very thin films ( 300 A), which accounts for its excellent writing sensitivity. Hydrogenated amorphous silicon is a wide band gap semiconductor, reducing the film thickness is impractical, since the film has a lower absorption coefficient in the red. It has been shown that ablation of a very thin Ge film in a trilayer structure requires three times more energy than Te (Bell and... 

Following these recent successful developments, trilayer hybrid NC/polymer devices were reported, constituting a film of CdSe/ZnS NCs a few monolayers thick sandwiched between films of PVK (hole transporter) and butyl-PBD (electron transporter) [23]. All the layers were deposited by a spin-coating technique from dissimilar solvents (either organics or water). These devices showed 20 times the external quantum efficiency (0.2 %) and less than half the threshold voltage of a single-layer device based on the PVK/NC/PBD blend. These improvements upon going from a blend to a trilayer structure were attributed to more balanced carrier conduction to and enhanced recombination in the NC layer. 

FIGURE 5.51 Trilayer structure of a typical ablative-mode optical disc. 

FIGURE 16.14 Trilayer structure of atypical ablative-mode optical disk. (From Clark, M.G., Materials for optical storage, Chem. Ind., 258, 1985. With permission.)... 

PVDF) methanol barrier layer was placed between two outer Nation layers (Kim et al. 2004a,b). The trilayer structure was prepared by spraying 5 wt% Nation solution directly onto both sides of a Naflon-PVDF him. Both proton conductivity and methanol permeability were controlled by the composition and thickness of the Nahon-PVDF layer. The DMFC performance of a trilayer system, composed of a 10 pm thick him of Nahon-PVDF (55 wt% of PVDF) with two 20 pm thick outer layers of Nahon, was better than that of Nahon 112 (54 pm thick), while the methanol crossover was rednced by 64%, as compared with that of Nahon 112, but there was no rednction in crossover, as compared with a thicker Nahon 117 membrane (Kim etal. 2004b). 

Fig. 5.1 Illustration of a trilayer PPy actuator (a) Working principle of a trilayer bender the sectional view of the trilayer structure (left) and bending upon application of a voltage (right) (b) observed large bending deformation. Reprinted from [Fang and Tan (2010)1 with permission from Elsevier, Copyright 2010.

F re 4.14 Schematic diagram showing the process of encapsulation of FcjOj particles with a trilayer structure. 

Fig. 12. Image acquired at 285.2 eV of a trilayer structure consisting of a 60-nm thick film of polystyrene (PS) coated on each side with 30 nm of SiO, . Annealing above the glass-transition temperature of PS results in the observed morphology. Profiles that emphasize PS (top profile labeled 285 eV) and spectra show that significant amounts of PS remain in the thin regions. Note that the preabsorption edge profile at 281 eV is essentially flat. (Data acquired with the ALS BL7.0 STXM.) Courtesy of A. P. Hitchcock, McMaster University, and J. Butcher, Guelph University.

Pressure-area isotherms indicate the an hiphiles of I and II on pure water both had identical take-off areas of 25 AVmolecule, corresponding to the molecular cross-section of the hydrocarbon-diacetylene stmcture. The film of I collapses at low pressure ( 12 ihN/m), but upon over-conpression reaches a stable solid phase with a limiting molecular area of 8 AVmolecide. This overcompressed state corresponds to a stable trilayer structure. The film of II was stable as a monolayer with a collapse pressure of ca. 35 mN/m and an extrapolated molecular area at zero pressure of 25 A /molecule. After equilibration, films were polymerized to the blue-phase by e qrosure to incidence powers of 40 pW/cm for I and 23 pW/cm for II over a period of 30 sec. Red-phase films were produced by exposing the trilayer of I to 500 pW/cm and the monolayer of II to 40 pW/cm for 5 min. 

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