In modern organic electronics and optoelectronics, anisotropic packing/alignment of charge transport functionalities has been recognized as a crucial factor for construction of high-performance devices. Depending upon the inherent charge transport direction within a device, molecular-scale “edge-on” orientation of charge-transporting hosts is favorable for organic field-effect transistors (OFETs), while the “face-on” orientational counterpart is preferential for organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs).<br/>Solution-cast polymer thin films for hole transport layer (HTL) devices in OLED display applications have been proposed in recent years. In this regime, a key requirement for the HTL device is high hole mobility and transport to the emission layer. We developed a novel solution-cast polymeric material that can achieve unprecedented high degrees of anisotropy, which we attribute to successful alignment of the charge carrying moieties. The structure-property relationship between obtained anisotropic data with polymer topology, monomer selection, and charge carrier group will be described in detail, as well as the effect of film processing. These results will be then correlated with measurement of charge transport using hole-only device and compared to control devices using the compositionally analogous polymer films but with little or no anisotropic molecular packing. While the films of this study were too thin to fully interpret the results in terms of measured hole mobility, the preliminary data indicate facile charge transport is commensurate with a high degree of anisotropic alignment. From these results, we propose the topological design strategy for anisotropic alignment of polymer, which is of potential usefulness for solution-processable HTL films with high charge mobilities.

Topological design of hole transporting polymers for highly anisotropic alignment in solution processed thin films

256th National Meeting (2018)

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