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.

Lead-free double perovskites have been considered as a potential environmentally friendly photovoltaic material for substituting the hybrid lead halide perovskites due to their high stability and nontoxicity. Here, lead-free double perovskite Cs₂AgBiBr₆ films are initially fabricated by single-source evaporation deposition under high vacuum condition. X-ray diffraction and scanning electron microscopy characterization show that the high crystallinity, flat, and pinhole-free double perovskite Cs₂AgBiBr₆ films were obtained after post-annealing at 300 °C for 15 min. By changing the annealing temperature, annealing time, and film thickness, perovskite Cs₂AgBiBr₆ solar cells with planar heterojunction structure of FTO/TiO₂/Cs₂AgBiBr₆/Spiro-OMeTAD/Ag achieve an encouraging power conversion efficiency of 0.70%. Our preliminary work opens a feasible approach for preparing high-quality double perovskite Cs₂AgBiBr₆ films wielding considerable potential for photovoltaic application.

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.