The size-dependent electronic and phononic configurations of single atoms and nanoclusters enable tailored functionalities. Their synergistic effects also attract attention, yet precise control of anti-aggregation states during high-temperature operations poses formidable challenges in multiple fields such as fuel cells and thermoelectrics. Herein, we develop a solution-processed strategy to precisely incorporate Pt species as isolated atoms (Pt1) and sub-nanoclusters (Ptn, ∼1 nm) in Bi2S3. Notably, Ptn of 1 nm size exhibit significant advantages over larger-size counterparts in tuning electronic structure and optimizing charge transfer. Furthermore, Pt1 and Ptn scatter 1 Å- to 1 nm- wavelength phonon that is conventionally underexplored. The 1 nm Ptn exhibits distinct force constant as compared to 3 nm Ptn, leading to ultra-strong phonon Rayleigh scattering, which in turn significantly reduces thermal conductivity. The optimized Bi2S3-Pt1/Ptn composite achieves breakthrough thermoelectric performance, attaining a maximum zT of 1.02 at 773 K and single-leg conversion efficiency of 1.58%, both setting benchmarks for Bi2S3 systems. This strategy can also be extended to other thermoelectric material systems such as Bi0.4Sb1.6Te3, PbTe, or other fields including solid-state batteries and solar cells.
Hua et al. (Tue,) studied this question.