Preparation of In0.5Sn0.5Se Crystal via a Zone Melting Method and Evaluation of its Thermoelectric Properties

Indium selenides (InSe) is a promising layer-structured semiconductor with broad potential applications in photovoltaics, diodes, and optic devices, but its thermoelectric performance is limited by the high thermal conductivity. In this work, by alloying high-performance thermoelectric SnSe in InSe, the In_0.5Sn_0.5Se crystal is prepared via a zone melting method. The density of In_0.5Sn_0.5Se crystal is measured as 5.81 g cm⁻³ which is between the density of pure SnSe and InSe. The XRD measurements indicate that the grown In_0.5Sn_0.5Se crystal consists of InSe and SnSe crystals with a preferred orientation along (00l) and (h00) planes, respectively. SEM and EDS analysis reveal that eutectic InSe and SnSe phases interdigitate with each other. The thermogravimetry analysis shows a slow decrease at a temperature ≈700 °C. In_0.5Sn_0.5Se crystal displays a n-type conduct behavior, the electrical conductivity σ is ≈0.02 Scm⁻¹ at room temperature and increases to 8.4 Scm⁻¹ under 820 K. The highest power factor PF is estimated to be ≈0.36 µWcmK⁻² near 570 K. The InSe-SnSe phase boundaries lead the thermal conductivity of In_0.5Sn_0.5Se crystal to be as low as 0.29 Wm⁻¹K⁻¹. Due to the low lattice thermal conductivity, In_0.5Sn_0.5Se crystal shows a ZT value of 0.04 at 600 K in this work.