Controllable Nonclassical Conductance Switching in Nanoscale Phase-Separated (PbI<sub>2</sub> )<sub>1-</sub> <sub>x</sub> (BiI<sub>3</sub> )<sub>x</sub> Layered Crystals.

Alexander, Grant C B; Krantz, Patrick W; Jung, Hee Joon; Davis, Samuel Kenneth; Xu, Yaobin; Dravid, Vinayak P; Chandrasekhar, Venkat; Kanatzidis, Mercouri G · Adv Mater · 2021

basic_science · Level V

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Abstract

Layered 2D (PbI<sub>2</sub> )<sub>1-</sub> <sub>x</sub> (BiI<sub>3</sub> )<sub>x</sub> materials exhibit a nonlinear dependence in structural and charge transport properties unanticipated from the combination of PbI<sub>2</sub> and BiI<sub>3</sub> . Within (PbI<sub>2</sub> )<sub>1-</sub> <sub>x</sub> (BiI<sub>3</sub> )<sub>x</sub> crystals, phase integration yields deceptive structural features, while phase boundary separation leads to new conductance switching behavior observed as large peaks in current during current-voltage (I-V) measurements (±100 V). Temperature- and time-dependent electrical measurements demonstrate that the behavior is attributed to ionic transport perpendicular to the layers. High-resolution transmission electron microscopy reveals that the structure of (PbI<sub>2</sub> )<sub>1-</sub> <sub>x</sub> (BiI<sub>3</sub> )<sub>x</sub> is a "brick wall" consisting of two phases, Pb-rich and Bi-rich. These brick-like features are 10s nm a side and it is posited that iodide ion transport at the interfaces of these regions is responsible for the conductance switching action.