Charge carrier mobility, photovoltaic, and electroluminescent properties of anthracene-based conjugated polymers bearing randomly distributed side chains

Abstract

This article reports on the synthesis, characterization, and properties of various anthracene-containing poly (p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene) (PPE-PPV) polymers (AnE-PVs) bearing statistical distributions of various side chains. Primarily, the ratio of linear octyloxy and branched 2-ethylhexyloxy side chains at the poly(p-phenylene vinylene) (PPV) parts was varied, leading to the polymers stat, stat1, and stat2. Furthermore, polymers also containing asymmetric substituted PPV and poly(p-phenylene ethynylene) units (bearing methoxy and 2-ethylhexyloxy side chains) were prepared yielding stat3, stat4, and stat5. These materials exhibit a broad variation in their photovoltaic properties. It is once more shown that side chains and their distribution can crucially affect the photovoltaic device performance. The introduction of units with asymmetric substitution into these systems seems to be harmful for their utilization in photovoltaic applications. Organic field-effect transistors were fabricated to investigate hole mobilities in these new materials. Large variance was observed, falling in the range of almost two orders of magnitude, indicating rather different pp stacking behavior of the polymer backbones owing to side-chain modifications. Moreover, a selection of the new polymeric systems was investigated regarding their potential for light-emitting diode (LED) applications. Polymer LEDs using the polymers AnE-PVstat, -stat3, -stat4, and -stat5, as the active layer showed turn-on voltage of similar to 2 V and exhibited red light emission. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012