• • Quadruple-band synglisis in p-type SnS crystals, achieved via SnS₂ introduction, activates four valence bands and promotes simultaneous energy and momentum convergence, yielding a significant enhancement in power factor (PF = S²σ) and ZT compared to prior triple-band convergence strategies.
• • The engineered SnS exhibits an exceptionally wide bandgap of 46 kBT, which is 4.6–7.7 times larger than the conventional 6–10 kBT range deemed ideal for thermoelectric cooling, yet it still functions as a viable refrigeration material, expanding the operational envelope for wide-bandgap thermoelectrics.
• • Single-crystal p-type SnS leverages high in-plane carrier mobility and an asymmetric layered structure to support complex electronic band engineering, enabling effective hole doping and multiband interactions that decouple effective mass (m*) from carrier mobility (μ).
• • The material system addresses the critical supply-chain risk of tellurium scarcity in commercial Bi₂Te₃ alloys by utilizing earth-abundant, nontoxic, and low-cost tin and sulfur, offering a sustainable alternative for large-scale thermoelectric power generation and Peltier cooling.