Small-molecular OLEDs

The existing OLED fabrication procedures fall into two major categories (1) thermal vacuum evaporation of the organic layers in small molecular OLEDs, and (2) wet coating techniques of the polymer layers in PLEDs. 

For small molecular weight, OLEDs with randomly oriented dipoles, and taking into account the light reflected by the back cathode (roughly multiplying by a factor of 2), l/(2 2) is obtained. With n = 1.7, we find around 17%. A... 

Since the initial report in 1999 using/ac-1 as an emitter achieved highly efficient phosphorescent OLEDs, many lr(C N)3-type Ir complexes, including small molecular complexes [8,9,15] and dendritic complexes [72-78], have been reported. The synthesis and structure of these complexes have been thoroughly investigated. 

There have been numerous studies of the electrical and emission properties of conjugated polymer-, small molecule-, and molecularly doped polymer-based OLEDs. The current-voltage and radiance-voltage characteristics have been nica sured as a function of thickness of the organic layer, temperature, different metal electrodes, etc. in an attempt to understand the device physics. A major factor in hibiting progress is the purity of the organic impurities that are incorporated dur-... 

Since the pioneering studies on OLEDs using small molecules and polymers [1, 2], both small molecules and polymers have been studied for use as materials in OLEDs. Small organic molecules that readily form stable amorphous glasses above room temperature, i. e., amorphous molecular materials [3], and polymers containing it-electron systems in the main chain, i.e., it-conjugated polymers, have been proven to be promising candidates for materials for OLEDs. 

A typical definition that is often made when describing OLEDs is to categorize them as either small molecule or polymer-based devices. However, this distinction is somewhat misleading since small molecule- and polymer-based OLEDs do not markedly differ in their operating principles. The mechanistic discussions given Section 12.04.2.1 apply equally well to both types of devices. A more logical way to differentiate OLEDs is by the fabrication method. Molecular materials (typically referred to as small molecules) can be distilled or sublimed at reduced pressure, and are... 

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