Synthesis and Electronic Spectra of Substituted p-Distyrylbenzenes for the Use in Light-Emitting Diodes
✍ Scribed by Ulf Stalmach; Heiner Detert
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 80 KB
- Volume
- 342
- Category
- Article
- ISSN
- 1615-4150
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✦ Synopsis
Poly(p-phenylenevinylene) and its derivatives are one of the preferred groups of materials for the use as emissive layer in organic polymer light emitting diodes [1 -4]. Several groups investigated the photochemistry and particularly the photophysical behaviour of these polymers in order to establish knowledge of the fundamental properties that are responsible for the efficiencies of the devices as well as their amelioration [3 -9]. However, the fact that the parent polymer is insoluble and intractable prevents its complete characterization so that systematic investigations on structure-property relationships are almost impossible. A part of this problem can be circumvented by the investigation of model compounds. This approach, the estimation of the properties of a polymer by investigation of oligomers as model compounds is widely used, especially in the field of conjugated polymers [10 -15].
Oligo(phenylenevinylene)s are useful as model compounds for the corresponding polymers and as luminescent material in Organic Light Emitting Diodes (OLEDs). Herein, the synthesis and the electronic spectra of a series of substituted distyrylbenzenes (DSBs) with a great variety of position, number, and character of substituents is reported. In order to elucidate the influence of different substitution patterns on the absorption and emission spectra, electron donors like dimethylamino and alkoxy side chains, a well as electron withdrawing groups like sulfones or nitriles and combinations of them were studied. Electron-donating ether groups have been used extensively in the field of conjugated polymers, as they reduce the band gap and allow to attach solubilising side chains. Sulfones and nitriles on the other hand, are electron withdrawing, which is especially important for a balanced charge carrier injection into the emitting material in a LED [16, 17] and