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Known as a weak topological insulator(TI),BiSe structurally exhibits alternating stacks of quantum spin Hall bilayer(“Bi2”)and three-dimensional TI layer(“Bi2Se3”).The low lattice thermal conductivity of BiSe due to the presence of Bi2 bilayers promises potentially good thermoelectric performance.Herein,the thermoelec-tric properties of nominal Bil-xCuxSe samples were stud-ied as the functions of the content of Cu additive and temperature.It is found that Cu additives in BiSe(1)profoundly affect the texture of densified polycrystalline samples by inclining the crystallographic c-axis parallel toward the pressure direction in the densification process,(2)increase considerably the effective mass and thus the Seebeck coefficient,and(3)yield point defects and Cu-Se secondary phases that effectively scatter heat-carrying phonons.As a result,the optimized electrical and thermal properties yield a thermoelectric figure of merit of zT～0.29 in Bi1-xCuxSe(x = 0.03)sample at 467 K in parallel to the pressure direction and a zT～0.20 at 468 K in the perpendicular direction.