Electron-emitting materials

Electron-emitting materials (commonly referred to as thermoionic emitters) can be classified as pure-metal emitters (e.g., W, Ta), monolayer-type emitters, oxide emitters, chemical-compound emitters, and finally alloy emitters. Thermoionic properties of selected materials are listed in Table 9.8. 

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An MCP is a glass disk perforated with a large number of small-diameter (10-100 )Lim) holes or channels. Each channel is a glass tube coated with a resistive secondary electron-emitting material. If a voltage is applied, each channel acts as an electron multiplier. 

Cathode coated with electron-emitting material and fitted with cathode shield... 

Central cathode The cathode is a metal cylinder at the center of the magnetron that is coated with an electron-emitting material. In operation, the cathode is heated to a temperature high enough to cause electrons to boil off the coating. 

The opto-electronic properties of branched structures have been an area of some interest for a number of years, especially as NLO and light-emitting materials [82]. In particular, the use of u-conjugated dendrimers (mono-disperse macromolecules [83]) has flourished for a number of reasons ... 

Field emission displays are VFDs that use field emission cathodes as the electron source. The cathodes can be molybdenum microtips,33-35 carbon films,36,37 carbon nanotubes,38" 16 diamond tips,47 or other nanoscale-emitting materials.48 Niobium silicide applied as a protective layer on silicon tip field emission arrays has been claimed to improve the emission efficiency and stability.49 ZnO Zn is used in monochrome field emission device (FED) displays but its disadvantage is that it saturates at over 200 V.29... 

The secondary electrons emitted from the sample are attracted to the detector by the collector screen. Once near the detector, the secondary electrons are accelerated into the scintillator by a positive potential maintained on the scintillator. Visible light is produced by the reaction of the secondary electrons with the scintillator material. The emitted light is detected by a photomultiplier tube, which is optically coupled to the scintillator via a light pipe. The PMT signal is then transferred to the grid of a cathode ray tube (CRT). Data collection... 

Electron transport materials for organic light-emitting diodes A.P. Kulkarni, C.J. Tonzola, A. Babel, and S.A. Jenekhe Chem. Mater., 16 4556-4573... 

In the effort to make pure blue-emitting materials Shim and coworkers [146] synthesized a series of PPV-based copolymers containing carbazole (polymers 95 and 96) and fluorene (polymers 97 and 98) units via Wittig polycondensation. The use of trimethylsilyl substituents, instead of alkoxy groups, eliminates the electron donor influence of the latter and leads to chain distortion that bathochromically shifts the emission (Amax = 480 nm for 95 and 495 nm for 97). In addition, a very high PLQY was found for these polymers in the solid state (64 and 81%, respectively). Single-layer PLEDs fabricated with 95 and 97 (ITO/polymer/Al) showed EL efficiencies of 13 and 32 times higher than MEH-PPV, respectively (see also Ref. [147] for synthesis and PLED studies of polymers 99 and 100) (Chart 2.20). 

M.M. Alam, and S.A. Jenekhe, Polybenzobisazoles as efficient electron-transport materials for improving the performance and stability of polymer light-emitting diodes, Chem. Mater., 14 4775-4780, 2002. 

E.-N. Chang and S.-A. Chen, Cyano-containing phenylene vinylene-based copolymer as blue luminescent and electron transport material in polymer light-emitting diodes, J. Appl. Phys., 85 2057-2061, 1999. 

C.J. Tonzola, M.M. Alam, B.A. Bean, and S.A. Jenekhe, New soluble n-type conjugated polymers for use as electron transport materials in light-emitting diodes, Macromolecules, 37 3554-3563,2004. 

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