Exploring new near-room-temperature thermoelectric materials is significant for replacing current high-cost Bi₂Te₃. This study highlights the potential of Ag₂Se for wearable thermoelectric electronics, addressing the trade-off between performance and flexibility. A record-high ZT of 1.27 at 363 K is achieved in Ag₂Se-based thin films with 3.2 at.% Te doping on Se sites, realized by a new concept of doping-induced orientation engineering. We reveal that Te-doping enhances film uniformity and (00l)-orientation and in turn carrier mobility by reducing the (00l) formation energy, confirmed by solid computational and experimental evidence. The doping simultaneously widens the bandgap, resulting in improved Seebeck coefficients and high power factors, and introduces Te_Se point defects to effectively reduce the lattice thermal conductivity. A protective organic-polymer-based composite layer enhances film flexibility, and a rationally designed flexible thermoelectric device achieves an output power density of 1.5 mW cm⁻² for wearable power generation under a 20 K temperature difference.

Ag₂Se shows significant potential for near-room-temperature thermoelectric applications, but its performance and device design are still evolving. In this work, we design a novel flexible Ag₂Se thin-film-based thermoelectric device with optimized electrode materials and structure, achieving a high output power density of over 65 W m⁻² and a normalized power density up to 3.68 μW cm⁻² K⁻² at a temperature difference of 42 K. By fine-tuning vapor selenization time, we strengthen the (013) orientation and carrier mobility of Ag₂Se films, reducing excessive Ag interstitials and achieving a power factor of over 29 μW cm⁻¹ K⁻² at 393 K. A protective layer boosts flexibility of the thin film, retaining 90% performance after 1000 bends at 60°. Coupled with p-type Sb₂Te₃ thin films and rational simulations, the device shows rapid human motion response and precise servo motor control, highlighting the potential of high-performance Ag₂Se thin films in advanced applications.

A flexible n-type Ag₂Se thin film with a high power factor (PF) of 21.6 μW cm⁻¹ K⁻² and a ZT value over 0.6 was successfully prepared by a facile self-assembled growth method.

Nanocomposite engineering decouples the transport of phonons and electrons. This usually involves the in-situ formation or ex-situ addition of nanoparticles to a material matrix with hetero-composition and hetero-structure (heC-heS) interfaces or hetero-composition and homo-structure (heC-hoS) interfaces. Herein, a quasi homo-composition and hetero-structure (hoC-heS) nanocomposite consisting of Pnma Bi₂SeS₂ - Pnnm Bi₂SeS₂ is obtained through a Br dopant-induced phase transition, providing a coherent interface between the Pnma matrix and Pnnm second phase due to the slight structural difference between the two phases. This hoC-heS nanocomposite demonstrates a significant reduction in lattice thermal conductivity (~0.40 W m⁻¹ K⁻¹) and an enhanced power factor (7.39 μW cm⁻¹ K⁻²). Consequently, a record high figure-of-merit ZT_max = 1.12 (at 773 K) and a high average figure-of-merit ZT_ave = 0.72 (in the range of 323–773 K) are achieved. This work provides a general strategy for synergistically tuning electrical and thermal transport properties by designing hoC-heS nanocomposites through a dopant-induced phase transition.

N-Type polycrystalline SnSe with Ti, Pb co-doping was synthesized by combining mechanical alloying (MA) with spark plasma sintering (SPS). It is revealed that Ti is an effective cationic dopant to convert SnSe from a p-type to an n-type semiconductor, and the thermoelectric performance of the Ti-doped SnSe is also improved in comparison with the pristine sample due to an enhanced power factor. Furthermore, after further Pb doping, an obviously improved electrical conductivity together with a moderate Seebeck coefficient can be achieved, which results in an improvement of the power factor with a maximum value of 300 μW m⁻¹ K⁻² at 773 K. Meanwhile, the lattice thermal conductivity is significantly reduced because of the enhanced phonon scattering owing to the mass and strain fluctuations. Therefore, a final ZT value of 0.4 was obtained for composition of Sn_0.74Pb_0.20Ti_0.06Se at 773 K, which is a conservative value for n-type SnSe with cationic dopant prepared by the simple preparation process of MA and SPS.

The effect of Pb and La substitution on the thermoelectric properties of BiCuSeO oxyselenide has been studied. It is revealed that Pb doping can significantly improve the electrical conductivity due to the increased carrier concentration, which results in a large power factor in the range of 700 to 800 μW m⁻¹ K⁻² at 873 K. In particular, the electrical transport properties can be further improved obviously over the entire measured temperature range after replacing some Bi³⁺ ions with La³⁺ ions in Bi_0.94Pb_0.06CuSeO. The electrical conductivity has increased from 408 S cm⁻¹ for Bi_0.94Pb_0.06CuSeO to 594 S cm⁻¹ for Bi_0.93Pb_0.06La_0.01CuSeO at 327 K due to the increased carrier mobility. Combining with the moderate Seebeck coefficient which is over 124 μV K⁻¹, the power factor has been significantly improved. An optimal value of 1059 μW m⁻¹ K⁻² at around room temperature is achieved for Bi_0.93Pb_0.06La_0.01CuSeO and is much higher than most reported values. Additionally, the increased total thermal conductivity for the Pb-doped sample compared with the pristine sample has been suppressed after further doping the La element in Bi_0.94Pb_0.06CuSeO. Therefore, a maximum ZT value of nearly 0.90 at 873 K for the sample Bi_0.92La_0.02Pb_0.06CuSeO has been finally obtained, which is ∼36% and ∼16% higher as compared with those of the La-free sample Bi_0.94Pb_0.06CuSeO and the reported Pb-free sample Bi_0.92La_0.08CuSeO.