Refined Compensation Doping and Off-Center Distortions Induced Performance Enhancement in N-Type Skutterudites Thermoelectrics

The excellent performance of skutterudites is related to the interrelated filling fraction and doping limitation of the intricate matrix. Especially for the investigation of n-type electronegatively filling samples, the exceptionally low doping capacity at Sb sites leads to severely compromised thermoelectric performance. Here, a breakthrough is achieved in surpassing conventional doping limits by developing a novel “electrical compensation-bonding modulation” method, contributing to the reconfiguration of the unique X 4 ring structure (Consists of Sb 4 units) in S 0.2 Se 0.05 Co 4 Sb 12-x Te x skutterudites. The modulated bond hierarchy and disorder enable a concurrent regulation of phonon and carrier transport, resulting in a significant improvement of the transport properties. Building upon this foundation, a revolutionary off-center state has been introduced to the matrix via continuous doping of Se at Sb sites, aimed at suppressing the lattice thermal conductivity. Ultimately, a peak zT of 1.8 at 800 K is achieved, with an average zT of 1.1 across the 300–800 K temperature range. This work provides a universal approach to overcome doping limits in Co 4 Sb 12 -based thermoelectrics.