Control of Charge-Carrier Mobility via In-Chain Spacer Length Variation in Sequenced Triarylamine Functionalized...

A set of six perfectly regioregular pendant 2,7-bis(phenyl-m-toluylamino)fluorene (TPF) functionalized polyolefins for use as charge transporting materials in polymer light emitting diodes (PLEDs) were prepared and characterized. Synthesis of these materials is straightforward, requiring only three or four steps, depending on the polymer, and final isolated yields over all steps combined were greater than 40% in all but one case. Most notably, these materials exhibit charge-carrier mobilities that can be controlled over 3 orders of magnitude by variation of the number of intermediary carbons (spacer length) between the pendant TPF groups. The range of hole mobilities encompasses the electron mobilities of common electron transport materials/emitters such as Alq₃ and PBD, thus, affording the opportunity to fabricate electroactive polyolefin based PLEDs with well matched charge-carrier mobilities and improved performance. We believe this approach to charge-carrier mobility control in electroactive materials could be easily extended to other aryl systems with different HOMO-LUMO levels for energy level and mobility matching with various emitters.