1D-Sn2X3 (X = S, Se) as Promising Opto-Electronic and Thermo-Electronic Materials: A Comparison with 3D-Sn2X3.

Ever since the discovery of two-dimensional (2D) material graphene, humongous interest has been generated in exploring low dimensional materials that can be exfoliated from their three-dimensional counterpart and show enriched properties due to quantum confinement. Two members of Sn-S family, \mathbf{\mathit{Pnma}}-SnS and P\overline{3}m1-SnS_{2} that possess layered structure with 2D nanosheets stacked via. weak van der Waals (vdW) interactions, have widely been studied in this regard. While, the other member \mathbf{\mathit{Pnma}}-Sn_{2}S_{3} comprising 1D nanochains bound via. vdW interactions, has never been investigated in the view of exfoliated 1D analogue. In this work, we therefore comprehensively studied 1D-Sn_{2}X_{3} (X = S and Se) nanochains and demonstrated them to be stable and exfoliable from their bulk counterpart. Further, it is also shown that the exfoliated 1D nanochains can easily be identified from their bulk counterpart using Raman, infrared and X-ray spectroscopies. Our calculations predict a direct band gap of 2.35 eV (1.67 eV) for 1D-Sn_{2}S_{3} (1D-Sn_{2}Se_{3}) nanochain under Heyd, Scuseria, and Ernzerhof (HSE06) functional, with broad absorption region lying between 2-8 eV, lower reflection, high charge carrier mobility with ambipolar characteristics, as well as larger value of Seebeck coefficient and smaller value of the thermal conductivity, resulting in better thermo-electric figure of merit. These interesting electronic, optical, transport, and thermo-electric properties make 1D-Sn_{2}X_{3} nanochains potential candidates for the application in future opto-electronic and thermo-electronic devices, in fact, better than 3D-Sn_{2}X_{3} for few of the applications. Moreover, a detailed investigation of 3D-Sn_{2}Se_{3} is also been done in this work, which to the best of our knowledge is not done before.