Thermoelectric properties of Bi2-Ti O2Se with the shear exfoliation-restacking process

Abstract Bi2O2Se is a potential medium-temperature n-type thermoelectric material owing to its lower lattice thermal conductivity and larger Seebeck coefficient. However, very low electrical conductivity of pristine polycrystalline Bi2O2Se hinders further enhancement of its thermoelectric performance. In this work, the thermoelectric properties of Bi2O2Se were investigated by Ti-doping with the shear exfoliation- restacking process. The results show that both the electron content and mobility can be further improved by Ti-doping with the shear exfoliation-restacking process, thus a higher electrical conductivity can be obtained. (e.g., 368 S cm−1 of Bi1.99Ti0.01O2Se at room temperature) On the other hand, the thermal conductivity of Bi1.99Ti0.01O2Se is suppressed to 0.84 Wm−1 K−1 at 772 K. Finally, the ZT peak of Bi1.99Ti0.01O2Se is raised to 0.56, which is 1.2 times of that of un-doped sample. The results show that the thermoelectric properties of Bi2O2Se can be further optimized by Ti doping with the shear exfoliation-restacking process.