Semiconducting polymers have a wide variety of applications in organic electronics including solar cells, thermoelectric devices and LED displays, however the exciton and polaron dynamics that determine the efficiency of these devices are not well understood, particularly in terms of intra- verus inter-chain dynamics. So, we have developed a system of polymers in aligned mesoporous silica films, which allows for both isolation of small numbers of polymer chains and elongation of the polymer backbone.  Because optical transitions in polymers occur along the backbone our system allows interchain and intrachain interactions interactions to be probed separately using polarized optical spectroscopy.  By using a wide variety of polymers, including push-pull polymers in this mesoporous silica system, we can use the optical studies to understand the effects of both chain conformation and aggregation across all types of semiconducting polymers<i>.</i> From our absorbance and fluorescence studies we have shown that polarization ratios of more than 20 can be achieved when the polymers are in the pores.  We can also study the peak shift of the emission peaks, and thus the exciton delocalization, in the aligned samples. We have seen that crystalline polymers are more likely to delocalize excitons between chains, even when confined to the pores while more amorphous polymers see a significant increase in intra-chain delocalization when aligned in pores.  We have also seen that the structure of push-pull polymers and the nature of the electron withdrawing group affects both the ability to align in pores and the trends in excitons delocalization.  Overall we have shown that this system can be used across all types of semiconducting polymers to understand the exciton and polaron dynamics in both inter and intrachain interactions.<br/>

Polarized optical spectroscopy of semiconducting polymers in an aligned mesoporous silica system for the study of polaron dynamics

253rd National Meeting (2017)

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