By the coordinated implementation of shallow impurity level and multiscale defect engineering, this study achieves the simultaneous optimization of electrical transport and thermal conduction in GeTe-based thermoelectric (TE) materials. This synergistic mechanism originates from the unique electronic configuration of Ni, whose d–sp orbital hybridization introduces shallow impurity levels that promote valence band convergence, thereby enhancing the effective mass of carriers and the Seebeck coefficient. Concurrently, in situ reactions between Ni and Ge form NiGe nanophases (10–30 nm), constructing multiscale defect structures that enable full-spectrum phonon scattering and suppress the lattice thermal conductivity of the Ge_0.885Sb_0.1Ni_0.015Te sample to ~0.8 W∙m⁻¹∙K⁻¹ at 323 K. Leveraging this cooperative optimization, Ge_0.885Sb_0.1Ni_0.015Te attains a peak dimensionless figure of merit (ZT) value of 2.15 at 773 K and an average ZT_avg of ~1.45 (323–773 K). A fabricated single-leg device achieves a conversion efficiency of ~10% under ∆T = 420 K, ranking among the top performances in the field. This work establishes a solid foundation for enhancing the performance and expanding the applications of GeTe-based TE materials.

Flexible thermoelectric generators (f-TEGs) have emerged as among the most promising candidates to address the persistent energy supply challenges associated with wearable electronics. To achieve practical applications of inorganic π-shaped f-TEGs rapidly requires enhancing their output power density, which represents the primary and pivotal objective. This review distills three main factors that govern output power density, namely, the power factor of thermoelectric materials, the geometric and packaging configurations of f-TEGs, as well as the effective temperature gradient across the f-TEGs. Further, the principal optimization strategies adopted for these factors over recent years are outlined. The strategies encompass approaches such as carrier concentration modulation, carrier scattering mechanism regulation, and energy band engineering to enhance the power factor, finite element simulations and numerical computations for optimizing geometric structure and packaging, and the integration of hydrogels and phase change materials into flexible heat sinks to establish and maintain sufficiently large temperature differences. Additionally, the discussion extends to the flexibility of inorganic materials and generators themselves. Finally, the concluding section addresses the challenges and critical issues confronting the development of flexible thermoelectric materials and generators.