Efficient charge transport is needed in all electronic devices. For instance, the fill factor of solar cells is lowered when charge extraction is not efficient. In transistors, carrier mobility is directly linked to the transit time across the channel and therefore to switching speed. Carrier mobility is adversely affected by traps, which are regions where charge delocalization is suppressed. In this talk I will show how the degree of delocalization of charges can be measured using modulated spectroscopic methods. By combining this sensitive spectroscopy in the IR with theory, we can infer the “size” of the polarons and relate it to microstructural features. The delocalization of the polaron depends on charge density, as fixed by the gate voltage in an transistor architecture. A second type of trap, which is purely morphological, is unique to macromolecules. The polymer conformation dictated by the rigidity of the chain, induces kinks. When these kinks push charges against the direction of the field, a morphological trap is created. I will show how these traps affect charge transport. The effect of field and molecular weight will be described in more detail.

Traps in conjugated polymers: Morphological and disorder effects

253rd National Meeting (2017)

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