High Thermoelectric Performance in High‐Entropy AgMnGePbSbTe5 With Pb Vacancies

Why It Matters

The work proves vacancy engineering can substantially boost thermoelectric efficiency, moving Te‑based materials closer to viable waste‑heat recovery solutions.

Key Takeaways

• Pb vacancies raise hole concentration, boosting electrical conductivity.
• Band convergence increases effective mass, stabilizing Seebeck coefficient.
• Point‑defect scattering lowers lattice thermal conductivity.
• Peak ZT reaches 2.23 at 723 K, 34% improvement.
• High‑entropy chalcogenides become competitive for waste‑heat applications.

Pulse Analysis

Thermoelectric technology hinges on materials that can convert heat gradients into electricity with minimal losses, a goal quantified by the dimensionless figure‑of‑merit, ZT. Traditional approaches focus on alloying or nanostructuring, yet high‑entropy compounds—where multiple elements share a single lattice—offer intrinsic disorder that can scatter phonons while preserving carrier mobility. In this landscape, AgMnGePbSbTe5 emerges as a novel p‑type narrow‑bandgap semiconductor, and the deliberate introduction of lead vacancies adds a new lever for performance tuning, aligning with broader industry pushes for efficient waste‑heat harvesting.

The vacancy strategy operates on three synergistic fronts. First, removing Pb atoms creates acceptor states that elevate hole concentration, directly enhancing electrical conductivity and the power factor. Second, density‑functional theory calculations reveal that the altered electronic structure promotes convergence of multiple valence bands, increasing the density‑of‑states effective mass and thereby sustaining a high Seebeck coefficient despite the higher carrier density. Third, the vacancies act as point‑defect scatterers, disrupting phonon propagation and reducing lattice thermal conductivity. The combined effect delivers a peak ZT of 2.23 at 723 K and an average ZT of 1.31 across a broad temperature window, representing a 31‑34% uplift over the vacancy‑free material.

These results reposition high‑entropy telluride alloys as serious contenders in the thermoelectric market. Compared with conventional Pb‑based chalcogenides, the vacancy‑engineered AgMnGePb0.97SbTe5 matches or exceeds the best reported ZT values while offering a scalable synthesis route via controlled stoichiometry. For industries ranging from automotive to power generation, such materials could enable more cost‑effective recovery of low‑grade waste heat. Future research will likely explore combinatorial vacancy designs, integration with module engineering, and long‑term stability assessments, paving the way toward commercial deployment of high‑entropy thermoelectrics.