Enhancement of thermoelectric properties over a wide temperature range by lattice disorder and chemical potential tuning in a (CuI)<sub>y</sub>(Bi<sub>2</sub>Te<sub>3</sub>)<sub>0.95−x</sub>(Bi<sub>2</sub>Se<sub>3</sub>)<sub>x</sub>(Bi<sub>2</sub>S<sub>3</sub>)<sub>0.05</sub> quaternary system
RSC advances