Thermochromic Hybrid Ferroelastic Semiconductor with Thermal/Electrical/Optical Switching Responses

Multifunctional materials with multiple physical channel responses are extensively used in various high-tech fields due to their superordinary electrical, magnetic, optical, thermal, acoustic, and other functions. Despite significant progress in functional materials, the ones with multiphysical channel switching responses have long been a great challenge. Herein, we present a thermochromic organic-inorganic hybrid ferroelastic semiconductor [PPY]₂[CuCl₄] (PPY = 4-pyrrolidinopyridine) with three physical channel switching responses in thermal/electrical/optical properties. [PPY]₂[CuCl₄] undergoes a ferroelastic phase transition at 317 K, characterized by the Aizu notation <i>mmm</i>F2/<i>m</i>, accompanied by the emergence and disappearance of ferroelastic domains during the phase transition. It also exhibits continuous and stable switching between high- and low-dielectric states in the vicinity of 417 K. Moreover, it exhibits intriguing thermochromism (green ↔ chartreuse) and possesses potential semiconductor characteristics with a band gap of 2.31 eV. This study contributes to the advancement of ferroelastic materials and devices capable of multiphysical channel responses.