Yuqing Sun,Zhihao Li,Yujie Zong,Fulong Liu,Hongxiang Wang,Hui Sun,Chunlei Wang,Hongchao Wang
The intrinsic low lattice thermal conductivities originates from the complex anion bonding environment make quaternary chalcogenides potential thermoelectric materials. Here, the bonding environment of Se atom in Cu 2.1 Mn 0.9 SnSe 4 is further regulated by substituting Mn 2+ with equimolar pairing elements (Ag + and In 3+ ). The increase in both bond length and angle, together with the reduction in bond strength of Ag Se and In Se bonds, cause the doped samples to display strong anharmonicities ( γ ∼ 1.84–2.04). And the weakened bond strength also lower the sound velocities. Consequently, the κ L of the doped samples is effectively constrained, achieving a minimum value of 0.55 W⸱m −1 ⸱K −1 at 673 K in x = 0.10 sample. Ultimately, a zT value of 0.53 at 673 K is attained in x = 0.10 sample. The modification of bonding environment around anion is considered as an effective mean to optimize the thermoelectric performance of quaternary chalcogenides.
Great progress has been achieved in p-type SnS thermoelectric compound recently, while the stagnation of the n-type counterpart hinders the construction of thermoelectric devices. Herein, n-type sulfide PbSnS 2 with isostructural to SnS is obtained through Pb alloying and achieves a maximum ZT of ~1.2 and an average ZT of ~0.75 within 300–773 K, which originates from enhanced power factor and intrinsically ultralow thermal conductivity. Combining the optimized carrier concentration by Cl doping and enlarged Seebeck coefficient through activating multiple conduction bands evolutions with temperature, favorable power factors are maintained. Besides, the electron doping stabilizes the phase of PbSnS 2 and the complex-crystal-structure induced strong anharmonicity results in ultralow lattice thermal conductivity. Moreover, a maximum power generation efficiency of ~2.7% can be acquired in a single-leg device. Our study develops a n-type sulfide PbSnS 2 with high performance, which is a potential candidate to match the excellent p-type SnS.
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