Optical properties OLEDs

There are many organic compounds with useful electronic and/or optical properties and with sufficiently high volatility to be evaporable at a temperature well below that at which decomposition occurs. Since thermal evaporation lends itself to facile multilayering, organic compounds may be selected for use in one or more function electron injection, electron transport, hole injection, hole transport, andI or emission. A complete list of materials that have been used in OLEDs is too vast to be included here. Rather, we list those that have been most extensively studied. 

From optical point of view, an OLED structure can be considered as a multilayer thin-film system composed of absorbing and nonabsorbing materials, as shown in Figure 6.27. Therefore, the optical properties and optimal structure of such a multilayer device can be investigated by applying thin-film optical analysis techniques. Based on the theory of optical admittance analysis for analyzing the optical properties of a thin-film system [92], the optical properties of an OLED thin-film system can be simulated to reduce the ambient reflection. 

The outstanding optical properties of Pcs are also finding application in areas of technological and industrial interest such as the preparation of organic light emitting devices (OLEDs) in which Pcs have been used as active components [253-255],... 

A prime concern of the OLED/PLED community is the level of uncertainty and inconsistency of results found in published scientific literature. Here, we summarize an accurate method for measurement of OLED/PLED optical properties. 

Luminescent metal clusters have been studied for possible applications in OLED display technology as dopant emitters, in solar photoconversion chemistry as chromophores, and in sensor development for luminescence detection (for more information on optical properties of organometallic compounds, see Chapter 12.04). Some reviews of various classes of luminescent clusters are available. Most of these are clusters of group 10 or 11 metals. A representative set of results is summarized below, with other luminescent clusters listed in Table 2. 

The peculiar band structure of CPs is responsible for interesting optical properties including excitation driven visible light emission [or photolu-miniscence (PL)] in solution form. The use of CP for LEDs is inspired by possibility of electric field (E) driven luminiscence [or electroluminiscence (EL)] by the thin and defect free films of suitable CPs. The discovery of OLEDs dates back to 1989 and can be credited to Prof. Sir. Richard F. Friend (who is also known as Father of Organic Electronics ) and coworkers, who invented the first thin-film OLED based on electroluminiscent layer of PPV (only few nanometers thick) via a facile solution processing route... 

For technological applications, the NIR-luminescent lanthanide complexes have to be incorporated into a stable matrix because of their poor thermal stability and low mechanical strength. So far, the incorporation of luminescent lanthanide complexes in matrices, as a result, the NIR-luminescent lanthanide hybrid materials, is of widespread interest in material science as it allows construction of functional materials with various optical properties. The study of NIR-luminescent lanthanide complexes in hybrid materials is not only of fundamental interest but these materials also have a high potential for different applications (optical amplifiers, optical waveguides, OLEDs, etc.). In general, these hybrid materials have superior mechanical properties and have a better processability than the pure lanthanide complexes. Moreover, embedding a lanthanide complex in a hybrid matrix is also beneficial for its thermal stability and luminescence output. ... 

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