Macromolecules, Vol.45, No.2, 705-712, 2012
Perfectly Regioregular Electroactive Polyolefins: Impact of Inter-Chromophore Distance on PLED EQE
Acyclic diene metathesis polymerization (ADMET) was used to synthesize a series of perfectly regioregular polyolefins, in which the number of backbone atoms between pendant terfluorene groups was precisely controlled at 8, 14, or 20 carbons. Analogous random copolymers containing identical chromophore densities were also synthesized to study the impact of regioregularity on the performance of this class of materials in polymer light emitting diodes (PLEDs). Additionally, the backbone alkene remnants of ADMET were saturated to generate materials with somewhat different ordering. These saturated derivatives led to improvements in PLED external quantum efficiencies (EQEs) over their unsaturated analogues in most cases, with a large improvement in one material. Charge mobility, as manifested in current density during PLED characterization, and relative solid-state fluorescence quantum yield (Phi(F)) also exhibit reasonable dependencies, with longer distances between electroactive groups yielding lower PLED current densities and higher Phi(F). Regioregularity has the opposite effect, giving rise to higher current densities and lower Phi(F) as compared to regiorandom analogues.