Direct fabrication of highly-dense Cu2ZnSnSe4 bulk materials by combustion synthesis for enhanced thermoelectric properties

• Bulk Cu2ZnSnSe4 materials are directly produced by combustion synthesis under gas pressure or high gravity.
• Simultaneous densification is finished during synthesis to realize one-step preparation of dense samples.
• By In-doping the Cu2ZnSn0.9In0.1Se4 sample shows an enhanced ZT of 0.59 at 773 K.

Thermoelectric materials are attractive for solar thermal energy conversion and waste heat recovery. The preparation of bulk thermoelectric materials usually involves multi-step processes with considerable time and energy consumption. Here we report an alternative way called combustion synthesis to realize one-step and fast fabrication of bulk Cu2ZnSnSe4 thermoelectric materials. The combustion synthesis was carried out in 2 MPa Ar gas atmosphere or in a high-gravity field in order to reduce the porosity in samples and complete simultaneous densification during synthesis. Nearly full-dense Cu2ZnSnSe4 samples with a porosity of < 1% were prepared, showing thermoelectric properties similar to those of Cu2ZnSnSe4 materials prepared by other methods. The ZT of the Cu2ZnSnSe4 samples was clearly improved by partial substitution of Sn with In, and reached 0.59 at 773 K for the composition of Cu2ZnSn0.9In0.1Se4. Compared with the conventional melt growth and powder sintering methods, combustion synthesis offers a fast, one-step, and furnace-free way for directly producing bulk Cu2ZnSnSe4 samples, which may open up new possibilities for synthesis and applications of Cu2ZnSnSe4-based thermoelectric materials.

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