Synthesis of conjugated polymers for application in light-emitting diodes (PLEDs)

In the field of electroluminescent organic materials, conjugated polymers h ave attracted much attention over recent pears owing to their versatile syn thesis, their relative ease of processing and the possibility of establishi ng predictive structure-function relationships between chemical structures and optical properties. This review article highlights the advances made in the synthesis of conjugated polymers for use in light-emitting devices (LE Ds) covering the last two years. Research efforts were largely directed tow ards the improvement of the synthesis of monomers and polymers involving cl assical polymer structures such as poly(p-phenylene vinylene)s (PPVs), poly (p-phenylene)s (PPPs), poly(2,7-fluorene)s (PFs), or poly(2,5-thienylene)s (PTs). Control of the color of emission by modulation of the effective conj ugation length, improving balanced charge injection and transport propertie s by introduction of electron-donating or -withdrawing moieties directly in to the polymer backbone or enhancement of the emission efficiency by attemp ts to influence film morphology an some examples of recent research directi ons. All these investigations contributed to a significantly better underst anding of the chemical and physical processes spanning topics from the manu facturing process to the operation of LEDs and leading to the announcement of the first commercial products. In addition to the classical pi -conjugat ed polymers a few examples of rather unusual structures have also emerged. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.