Mixed-Metal Cu-Zn Thiocyanate Coordination Polymers with Melting Behavior, Glass Transition, and Tunable Electronic Properties

Abstract

<p>The solid-state mechanochemical reactions under ambient conditions of CuSCN and Zn(SCN)<sub>2</sub> resulted in two novel materials: partially Zn-substituted <i>α</i>-CuSCN and a new phase Cu<sub>x</sub>Zn<sub>y</sub>(SCN)<sub>x+2y</sub>. The reactions take place at the labile S-terminal, and both products show melting and glass transition behaviors. The optical band gap and solid-state ionization potential can be adjusted systematically by adjusting the Cu:Zn ratio. Density functional theory calculations also reveal that the Zn-substituted CuSCN structure features a complementary electronic structure of Cu 3<i>d</i> states at the valence band maximum (VBM) and Zn 4<i>s</i> states at the conduction band minimum (CBM). This work shows a new route to develop semiconductors based on coordination polymers which are becoming technologically relevant for electronic and optoelectronic applications.</p>