Work

Defect-Balanced YbTe Co-doping Unlocks Record Power Factor in Flexible p-Type BiSbTe Films

Year: 2026

Type: dataset

Abstract: The development of flexible thermoelectric generators is currently constrained by a significant performance asymmetry: while n-type materials have seen rapid progress, high-performance p-type films remain elusive. We bridge this gap by introducing a defect-balanced co-doping strategy for flexible Bi₀.₅Sb₁.₅Te₃ thin films, utilizing YbTe as a single-source dopant to simultaneously supply heavy-mass Yb and excess Te. This approach effectively decouples carrier concentration from mobility. The incorporation of 0.75 mol% YbTe tunes the hole concentration to an optimal ~1.3×1020 cm-3 while preserving carrier mobility, yielding a room-temperature power factor of 2.40 mW m-1 K-2—an 85% enhancement over pristine films. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) reveal that a mixed-valence Yb2+/Yb3+ state acts as a charge buffer, while the Te-rich environment suppresses detrimental donor vacancies. A flexible single-leg generator fabricated from these films delivers a power density of 18.7 W m-2 at ΔT = 25 K, matching the performance of state-of-the-art n-type flexible films. Furthermore, the device exhibits exceptional durability, retaining ≥90% of its output after 1,000 bending cycles (5 mm radius), proving that high thermoelectric efficiency and mechanical resilience can coexist.

Source: Zenodo (CERN European Organization for Nuclear Research)

DOI: 10.5281/zenodo.18241413