Phosphorescent PLEDs

PLEDs contain polymeric emissive materials that are almost exclusively processed by solution coating (spin coating or inkjetting). This has been discussed in Chapter 2. While most polymer work uses fluorescent emissive materials, there are a few examples of phosphorescent materials being incorporated into a polymer chain and being used as phosphorescent emitters. This part of the materials discussion will be covered in Chapter 4. 

The Characteristics of PLEDs Fabricated with Polymers Containing Phosphorescent Moieties as Pendant Groups (PFO Stands for PDOF 13)... 

Polymer light-emitting devices (PLEDs) have attracted considerable interest because of their potential use in portable electronic devices. PLEDs have improved the performance of devices by increasing the device stability and efficiency. Chang and coworkers fabricated an efficient PLED using [Ir(acac)(dbq)2] as the phosphorescent dopant of a pvk matrix layer and bbpo as the electron transport material. Trapping of charge carriers at the [Ir(acac)(dbq)2] dopant sites dominates the EL of the device. This is the first PLED that emits red electrophosphorescence centered at 610 nm, exclusively from the dopant and an EL efficiency of 8.5 cdA (luminance 1287 cdm ) biased at 14.5 mAcm . ... 

Subsequently, Cao et al. [30,31] designed and synthesized polymer 20-22 by similar method and the highly efficient saturated red-phosphorescent polymer light-emitting diodes (PLEDs) were achieved on the basis of copolymer 20. The best device performances are observed with an external quantum efficiency of 6.5% photon/electron (ph/el) at the current density of 38 mA/cm2, with the emission peak at 630 nm (x = 0.65, y = 0.31) and the luminance of 926 cd/m2. 

Finally, while the recent progress in phosphorescent dye-doped PLEDs provides a very competitive technology to achieve red and NIR electroluminescence, the synthetic versatility of thiophenes still makes them very attractive building blocks for precise tailoring of the properties of multicomponent light-emitting copolymers. 

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