Room Temperature Band-like Transport and Hall Effect in a High Mobility Ambipolar Polymer

TL;DR

This study reveals band-like transport and Hall effect at room temperature in a high-mobility, low-disorder semiconducting polymer, advancing understanding of charge transport mechanisms in organic electronics.

Contribution

It demonstrates the origin of band-like transport in a high-performance DPP-based polymer and links molecular design to low disorder and high mobility.

Findings

Ultra-low disorder (~16 meV) enables band-like transport at room temperature.

Hall mobility matches field-effect mobility in the high-temperature regime.

Systematic disorder tuning affects the delocalized transport window.

Abstract

The advent of new-class of high-mobility semiconducting polymers opens up a window to address fundamental issues in electrical transport mechanism such as hopping between localized states versus extended state conduction. Here, we investigate the origin of ultra-low degree of disorder (~ 16 meV) and band-like negative temperature (T) coefficient of the field effect electron mobility in a high performance diketopyrrolopyrrole (DPP)-based semiconducting polymer. Models based on the framework of mobility edge (ME) with exponential density of states are invoked to explain the trends in transport. The temperature window over which the system demonstrates de-localized transport was tuned by a systematic introduction of disorder at the transport interface. Additionally, the Hall mobility extracted from Hall-voltage measurements in these devices was found to be comparable to field effect mobility in the high T band-like regime. Comprehensive studies with different combinations of dielectrics and semiconductors demonstrate the effectiveness of rationale molecular design which emphasizes uniform-energetic landscape and low re-organization energy.