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

In the field of electroluminescent organic materials, conjugated polymers have attracted much attention over recent years owing to their versatile synthesis, their relative ease of processing and the possibility of establishing 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 (LEDs) covering the last two years. Research efforts were largely directed towards the improvement of the synthesis of monomers and polymers involving classical 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 conjugation length, improving balanced charge injection and transport properties by introduction of electron-donating or -withdrawing moieties directly into the polymer backbone or enhancement of the emission efficiency by attempts to influence film morphology are some examples of recent research directions. All these investigations contributed to a significantly better understanding of the chemical and physical processes spanning topics from the manufacturing process to the operation of LEDs and leading to the announcement of the first commercial products. In addition to the classical π -conjugated polymers a few examples of rather unusual structures have also emerged.