Pd3Se10: a semiconducting cluster-based material†

Abstract

Superatomic clusters have long attracted attention as active components in a broad range of optical and electronic technologies, making the discovery and understanding of new cluster-based materials an important frontier. Here, we establish the optimized synthesis and properties of a metastable palladium selenide Pd₃Se₁₀ phase comprised of Pd₆Se₂₀ cube-like clusters. The solution-phase electrochemically balanced reaction between Pd²⁺ and sodium polyselenide precursor mixtures, under precise reaction conditions, enables the formation of a crystalline product in high yields. The Raman fingerprint of Pd₆Se₂₀ shows that the cluster is also present in amorphous products that form at lower reaction temperatures. Pd₃Se₁₀ is stable up to 340 °C, above which it disproportionates into Se and orthorhombic PdSe₂. Finally, the optical absorption, electronic resistivity, and photoconductivity measurements indicate that crystalline Pd₃Se₁₀ is semiconducting with a 1.18 eV indirect gap. Overall, this understanding opens a pathway toward accessing a new superatomic building block which has potential in optoelectronic devices.