Toward dopant-free transparent electronics: Cu3SiS4 as a stable intrinsic <i>p</i> -type conductor

Abstract

Traditional transparent conductive materials rely on extrinsic doping of wide bandgap semiconductors, a route that faces thermodynamic limits for p-type systems. Here, an inverse strategy is adopted: start with an intrinsically high hole density sulfide and engineer its bandgap for optical transparency. By isovalent Sn → Si substitution in the p-type semiconductor Cu3SnS4, we obtain orthorhombic Cu3SiS4. First-principles calculations find the Fermi level 0.65 eV below the valence band maximum while retaining a wide 2.94 eV fundamental gap, so 40 nm thin films transmit 80% of visible light. Thermodynamic and kinetic stability analyses confirm its chemical stability, indicating that Cu3SiS4 should be a highly promising candidate for high-performance intrinsic p-type transparent conductive materials.