Controllable Nonclassical Conductance Switching in Nanoscale Phase-Separated (PbI2)1-x(BiI3)x Layered Crystals

Layered 2D (PbI2)(1-)(x)(BiI3)(x) materials exhibit a nonlinear dependence in structural and charge transport properties unanticipated from the combination of PbI2 and BiI3. Within (PbI2)(1-)(x)(BiI3)(x) 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 (PbI2)(1-)(x)(BiI3)(x) 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.