Inorganic electroluminescent devices

Novel Organo-electroluminescent Devices/Inorganic Devices 709... 

In this section, only luminescent materials that can be used in inorganic low voltage electroluminescent devices will be discussed in some detail. Phosphors are used for two reasons ... 

FIGURE 10.9 Schematic structure of an inorganic electroluminescent device with a transparent electrode made from a printing paste formulation of PEDT PSS (screen printing technique). 

Figure 14.11 Schematic structure of an inorganic electroluminescent device with a transparent electrode made from a screen printing paste formulation of PEDOT PSS. Erom 5. Kirchmeyer and K. Reuter, Scientific importance, properties and growing applications of poly(3,4-ethylenedioxythiophenes),. Mater. Chem. 15, 2077-2088 (2005). Reproduced by permission of The Royal Society of Chemistry...

Organic-inorganic hybrid materials have attracted extensive fundamental and practical interest/ Molecular design of hybrid materials could produce materials with tunable properties for optoelectronic devices, including optical waveguides,electroluminescent devices,nonlinear optical materials, photorefractive materials, and semiconductors/ ... 

Electroluminescent Device Using PbBr-Based Layered Perovskite Having Self-Organized Organic-Inorganic Quantum-Well Structure... 

In the beginning of thel970, with solely nematic liquid crystals in use, the twisted nematic TN-LCD became mainstream for LCDs in electronic watches and calculators. The multiplexed LCD incorporates capacitors in their matrix circuits which led to crosstalk between the matrix elements. Therefore the amplitude selection method was developed to create a uniform bias voltage to control the crosstalk such as 3-to-l or 2-to-l amplitude selection. This model was known as the matrix addressing technology of inorganic electroluminescent devices. In order to apply this to TN-LCDs, the two next characteristics have to be considered. 

The apphcation of a high electric field across a thin conjugated polymer film has shown the materials to be electroluminescent (216—218). Until recentiy the development of electroluminescent displays has been confined to the use of inorganic semiconductors and a limited number of small molecule dyes as the emitter materials. Expansion to the broad array of conjugated polymers available gives advantages in control of emission frequency (color) and facihty in device fabrication as a result of the ease of processibiUty of soluble polymers (see Chromogenic materials,electrochromic). 

The enormous progress in the field of electroluminescent conjugated polymers has led to performances of oiganic light-emitting devices (LEDs) that are comparable and in some aspects superior to their inorganic counterparts 11). Quantum efficiencies in excess of 5% have been demonstrated [2] and show that a high fraction of the injected carriers in a polymeric electroluminescence (EL) device form electronic excitations which recombine radiatively. 

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