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Enhanced thermoelectric properties of earth-abundant Cu2SnS3 via In doping effect


Ternary copper tin sulfide (Cu-Sn-S) compounds have been investigated for decades as promising candidates of earth-abundant thin film solar cell absorbers. Cu2SnS3 is a representative member of this material system, and is highly expected to be a potential thermoelectric material by the first-principles calculations. In this work, Cu2SnS3 bulk materials were synthesized by the mechanical alloying (MA) combined with spark plasma sintering (SPS), and their crystal structures, electronic transport properties and enhanced thermoelectric performance were systematically investigated. We found that pristine Cu2SnS3 is a p-type thermoelectric material with a relatively high thermopower up to 300 μV/K and low thermal conductivity below 1.0 W/m K above 700 K. It revealed that In doping is an effective means to improve the electrical transport properties, which leads to a figure of merit (ZT) of Cu2Sn0.9In0.1S3 close to 0.6 at the relatively low temperature (773 K).