Achieving Ultralow Lattice Thermal Conductivity and High Thermoelectric Performance in Bi2Te2.7Se0.3 Alloys via Introducing Organic & Inorganic Nanoparticles.

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N-type Bi2Te2.7Se0.3(BTS) is a state-of-the-art thermoelectric material owing to its excellent thermoelectric properties near room temperatures for commercial applications. However, its performance is restricted by its comparatively low figure of merit ZT. Here, it is shown that a 14% increase in power factor (PF) (at 300 K) can be reached through incorporation of inorganic GaAs nanoparticles due to enhanced thermopower originating from the energy-dependent carrier scattering. Besides, further incorporation of organic nanophase PEDOT: PSS can reduce its lattice thermal conductivity by 59% due to the strong scattering of middle- and low-frequency phonons. As a result, a peak ZT value of ZTmax ≈ 1.31 (at 373 K) and an average ZTave ≈ 1.10 (300-473 K) are achieved for the BTS/(0.4 wt.% GaAs + 0.5 wt.% PEDOT: PSS) sample. The present work demonstrates that incorporation of organic-inorganic nanophase is an effective way to improve the performance of BTS.