Advances in AgSbSe2- and AgSbTe2-Based Thermoelectric Materials: Structure–Property Relationships and Strategies for Enhanced Thermoelectric Performance

Abstract AgSbSe2 and AgSbTe2 are among the most intriguing chalcogenide-based thermoelectric materials, which are well-known for their high Seebeck coefficients and intrinsically low lattice thermal conductivity. Despite their seemingly simple chemical compositions, a comprehensive understanding of the origin of their intriguing physical properties remains elusive, and the determination of their accurate crystal structures continues to pose considerable challenges. The degree of cation ordering in AgSbTe2 and their specific arrangement remain to be fully established, while recent studies have revealed the presence of local structural distortion in the widely accepted rock-salt-type cubic structure of AgSbSe2. Despite these complexities, considerable advances in the thermoelectric performance of these materials have been achieved through various material design strategies. Recently, a maximum thermoelectric figure of merit (zT) of 2.6 at 573 K has been demonstrated in AgSbTe2 via enhanced atomic ordering on the cation sublattice, which makes the thermoelectric performance of AgSbTe2 on par with state-of-the-art thermoelectric materials like GeTe and PbTe. In this review, we discuss these recent advances in the thermoelectric performance of AgSbSe2 and AgSbTe2 and critically analyze the underlying strategies responsible for these improvements. We further examine the recent studies that provide insights into the elusive structural and physical properties of these compounds. Finally, we provide a comprehensive outlook on the current challenges and identify future research directions. This review offers a timely perspective on these intriguing I–V–VI2 compounds and provide insights that may help accelerate their developments toward practical and commercial thermoelectric applications.