A Quasi‐2D Polypyrrole Film with Band‐Like Transport Behavior and High Charge‐Carrier Mobility
Kejun Liu, Julien Réhault, Baokun Liang, Mike Hambsch, Yingying Zhang, Sezer Seçkin, Yunxia Zhou, Rishi Shivhare, Peng Zhang, Miroslav Položij, Tobias A. F. König, Haoyuan Qi, Shengqiang Zhou, Andreas Fery, Stefan C. B. Mannsfeld, Ute Kaiser, Thomas Heine, Natalie Banerji, Renhao Dong⧫, Xinliang Feng
Abstract
Abstract Quasi‐2D (q2D) conjugated polymers (CPs) are polymers that consist of linear CP chains assembled through non‐covalent interactions to form a layered structure. In this work, the synthesis of a novel crystalline q2D polypyrrole (q2DPPy) film at the air/H 2 SO 4 (95%) interface is reported. The unique interfacial environment facilitates chain extension, prevents disorder, and results in a crystalline, layered assembly of protonated quinoidal chains with a fully extended conformation in its crystalline domains. This unique structure features highly delocalized π‐electron systems within the extended chains, which is responsible for the low effective mass and narrow electronic bandgap. Thus, the temperature‐dependent charge‐transport properties of q2DPPy are investigated using the van der Pauw (vdP) method and terahertz time‐domain spectroscopy (THz‐TDS). The vdP method reveals that the q2DPPy film exhibits a semiconducting behavior with a thermally activated hopping mechanism in long‐range transport between the electrodes. Conversely, THz‐TDS reveals a band‐like transport, indicating intrinsic charge transport up to a record short‐range high THz mobility of ≈107.1 cm 2 V −1 s −1 .