Bi(Te, Se)-based compounds have attracted lots of attention for nearly two centuries as one of the most successful commercial thermoelectric (TE) materials due to their high performance at near room temperature. Compared with 3D bulks, 2D thin films are more compatible with modern semiconductor technology and have unique advantages in the construction of micro- and nano-devices. For device applications, high average TE performance over the entire operating temperature range is critical. Herein, highly c-axis-oriented N-type Bi(Te, Se) epitaxial thin films have been successfully prepared using the pulsed laser deposition technology by adjusting the deposition temperature. The film deposited at ~260 ℃ demonstrate a remarkable average power factor (PF_ave) of ~24.4 μW·cm⁻¹·K⁻² over the temperature range of 305–470 K, higher than most of the state-of-the-art Bi(Te, Se)-based films. Moreover, the estimated average zT value of the film is as high as ~0.81. We then constructed thin-film TE devices by using the above oriented Bi(Te, Se) films, and the maximum output power density of the device can reach up to ~30.1 W/m² under the temperature difference of 40 K. Predictably, the outstanding average TE performance of the highly oriented Bi(Te, Se) thin films will have an excellent panorama of applications in semiconductor cooling and power generation.

Cu₃SbSe₄, a copper-based sulfide free of rare earth elements, has received extensive attention in thermoelectric materials. However, its low carrier concentration restricts its widespread application. In this study, a microwave-assisted solution synthesis method was used to produce samples of Cu₃SbSe₄, which enabled the formation of CuSe in situ and increased the yield. Through the use of first-principles calculations, structural analysis, and performance evaluation, it was found that CuSe can enhance the carrier concentration and that induced nano-defects have a positive effect on reducing the lattice thermal conductivity. Moreover, doping with Sn decreases the band gap of the system and moves the Fermi level into the valence band, increasing the carrier concentration to 1.15 × 10⁻²⁰ cm⁻³. Finally, the zT value of the Cu₃Sb_0.98Sn_0.02Se₄ sample was achieved at 1.05 at 623 K when the theoretical yield of a single synthesis was 10 mmol.

Element doping and nano-inclusion embedding are effective approaches to enhance the electrical conductivities and decrease the lattice thermal conductivities of thermoelectric (TE) materials, respectively. However, the intrinsic low electrical thermal conductivities and high electrical properties are severely sacrificed, and the final figure of merit (ZT) is usually restricted. In this study, Ag doping and Pt quantum dot (QD) embedding were synchronously achieved via embedding Ag/Pt alloy QDs into the higher manganese silicides to avoid the conventional single-element doping strategy. The power factor (at 823 K) was enhanced from 1.57 × 10⁻³ W m⁻¹ K⁻² to 1.82 × 10⁻³ W m⁻¹ K⁻² (~16%) due to the ~18% increase in carrier concentration that was derived from the Ag doping effect. Simultaneously, the lattice thermal conductivity (at 823 K) decreased from 2.65 W m⁻¹ K⁻¹–1.92 W m⁻¹ K⁻¹ (~28%) because of the broadband phonon scattering effect that resulted from the residual Pt QDs inclusions. Synthetically, the optimal ZT value increased by ~52% from 0.42 to 0.64 at 823 K. This study demonstrated that incorporating metastable alloy QDs to obtain element doping and nano-inclusion embedding effects is a novel and feasible means to enhance the ZT value of HMS. This method is also possibly applicable to other alloy QD/TE composites.