Bi1.5Sb0.5Te1.7Se1.3 or in shortly BSTS is a vdW topological material and vdW superconductor with exciting superconducting properties from bulk to monolayer scales. BSTS is a 3D topological insulator and superconductor and the structural elemental composition is set at Bi1.5Sb0.5Te1.7Se1.3. This is an optimized composition of the topological insulator Bi2Te2Se (BST) in which the Te:Se ratio is reduced by replacing (substitutional) Bi with Sb atoms.