Search

A series of blue organic light-emitting diodes with electron or hole blocking interlayer are fabricated. Different structures of blocking interlayers can influence the position of the recombination zone due to the fact that they confine carriers in different ways. We find that the double hole blocking interlayer structure can balance carrier injection more effectively. Its power and current efficiency are more stable and the current efficiency value is 30.2 cd/A at 1000 cd/m2. Decreasing the thicknesses of the emitting layer and interlayers is in favor of the power efficiency. The performance of the device is also affected by changing the interlayer position when we use hole and electron blocking material as interlayers simultaneously.

In situ TEM, TEM and Raman studies of the effect of heat treatment on the microstructural processes of an Al/a-SiC:H film have been undertaken. The TEM results show that the interface of the films is inert at room temperature, and that annealing below 350 degrees C does not cause a significant interfacial reaction. However, silicon precipitation occurs at a temperature of about 350 degrees C. Higher temperatures lead to the formation of the Al4C3 compound. Ultimately, the reaction products of the films are determined to be Al4C3 and silicon after annealing at 550 degrees C. Raman scattering results also confirm the formation and growth of Si crystallites.

An n-ZnO:Al/p-boron-doped diamond heterostructure electroluminescent device is produced, and a rectifying behavior can be observed. The electroluminescence spectrum at room temperature exhibits two visible bands centred at 450 nm–485 nm (blue emission) and 570 nm–640 nm (yellow emission). Light emission with a luminance of 15 cd/m2 is observed from the electroluminescent device at a forward applied voltage of 85 V, which is distinguished from white light by the naked eye.

Graphene films are deposited on copper (Cu) and aluminum (Al) substrates, respectively, by using a microwave plasma chemical vapour deposition technique. Furthermore, these graphene films are characterized by a field emission type scanning electron microscope (FE-SEM), Raman spectra, and field emission (FE) I–V measurements. It is found that the surface morphologies of the films deposited on Cu and Al substrates are different: the field emission property of graphene film deposited on the Cu substrate is better than that on the Al substrate, and the lowest turn-on field of 2.4 V/μm is obtained for graphene film deposited on the Cu substrate. The macroscopic areas of the graphene samples are all above 400 mm2.

ZnO films with special textures are fabricated on Mo-coated Al2O3 ceramic substrates by the catalyst-free electron beam evaporation method, and the as-deposited films are treated by hydrogen plasma. It is found that the surface morphologies of the films are changed significantly after hydrogen plasma treatment and that the films consist of vertically standing and intersecting nanosheets. A lower turn-on field of 1.2 V/μm and an enhanced current density ~0.11 mA/cm2 at 2.47 V/μm are achieved. The low threshold field and the high emission current density are attributed primarily to the unique shape and smaller resistivity of the ZnO nanosheet films.