Cs3Sb5Se9 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one Se(6), two equivalent Se(5), three equivalent Se(1), and three equivalent Se(2) atoms. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 3-coordinate geometry to one Se(1), one Se(2), and one Se(5) atom. In the second Sb site, Sb(2) is bonded to two equivalent Se(2), two equivalent Se(4), and two equivalent Se(6) atoms to form a mixture of corner and edge-sharing SbSe6 octahedra. The corner-sharing octahedral tilt angles are 12°. In the third Sb site, Sb(3) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(6) atoms to form a mixture of corner and edge-sharing SbSe6 octahedra. The corner-sharing octahedral tilt angles are 12°. In the fourth Sb site, Sb(4) is bonded in a rectangular see-saw-like geometry to one Se(3), one Se(4), and two equivalent Se(6) atoms. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cs(1), three equivalent Cs(2), one Sb(1), and one Sb(3) atom to form a mixture of distorted face, corner, and edge-sharing SeCs4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 26-67°. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Cs(1), three equivalent Cs(2), one Sb(1), and one Sb(2) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Sb(4), and two equivalent Sb(3) atoms. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Sb(4), and two equivalent Sb(2) atoms. In the fifth Se site, Se(5) is bonded to four equivalent Cs(2) and two equivalent Sb(1) atoms to form a mixture of distorted face, corner, and edge-sharing SeCs4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 26-57°. In the sixth Se site, Se(6) is bonded in a 5-coordinate geometry to one Cs(1), one Cs(2), one Sb(2), one Sb(3), and one Sb(4) atom.
Cs3Sb5Se9 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic C2/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. Both Cs(1)-Se(1) bond lengths are 3.77 Å. Both Cs(1)-Se(2) bond lengths are 3.79 Å. Both Cs(1)-Se(3) bond lengths are 4.03 Å. Both Cs(1)-Se(4) bond lengths are 4.08 Å. Both Cs(1)-Se(6) bond lengths are 4.20 Å. In the second Cs site, Cs(2) is bonded in a 9-coordinate geometry to one Se(6), two equivalent Se(5), three equivalent Se(1), and three equivalent Se(2) atoms. The Cs(2)-Se(6) bond length is 3.70 Å. There is one shorter (3.70 Å) and one longer (3.79 Å) Cs(2)-Se(5) bond length. There are a spread of Cs(2)-Se(1) bond distances ranging from 3.66-3.94 Å. There are a spread of Cs(2)-Se(2) bond distances ranging from 3.71-4.05 Å. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 3-coordinate geometry to one Se(1), one Se(2), and one Se(5) atom. The Sb(1)-Se(1) bond length is 2.55 Å. The Sb(1)-Se(2) bond length is 2.56 Å. The Sb(1)-Se(5) bond length is 2.64 Å. In the second Sb site, Sb(2) is bonded to two equivalent Se(2), two equivalent Se(4), and two equivalent Se(6) atoms to form a mixture of corner and edge-sharing SbSe6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both Sb(2)-Se(2) bond lengths are 2.92 Å. Both Sb(2)-Se(4) bond lengths are 2.82 Å. Both Sb(2)-Se(6) bond lengths are 2.90 Å. In the third Sb site, Sb(3) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(6) atoms to form a mixture of corner and edge-sharing SbSe6 octahedra. The corner-sharing octahedral tilt angles are 12°. Both Sb(3)-Se(1) bond lengths are 3.00 Å. Both Sb(3)-Se(3) bond lengths are 2.77 Å. Both Sb(3)-Se(6) bond lengths are 2.91 Å. In the fourth Sb site, Sb(4) is bonded in a rectangular see-saw-like geometry to one Se(3), one Se(4), and two equivalent Se(6) atoms. The Sb(4)-Se(3) bond length is 2.96 Å. The Sb(4)-Se(4) bond length is 2.82 Å. Both Sb(4)-Se(6) bond lengths are 2.61 Å. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cs(1), three equivalent Cs(2), one Sb(1), and one Sb(3) atom to form a mixture of distorted face, corner, and edge-sharing SeCs4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 26-67°. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one Cs(1), three equivalent Cs(2), one Sb(1), and one Sb(2) atom. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Sb(4), and two equivalent Sb(3) atoms. In the fourth Se site, Se(4) is bonded in a 5-coordinate geometry to two equivalent Cs(1), one Sb(4), and two equivalent Sb(2) atoms. In the fifth Se site, Se(5) is bonded to four equivalent Cs(2) and two equivalent Sb(1) atoms to form a mixture of distorted face, corner, and edge-sharing SeCs4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 26-57°. In the sixth Se site, Se(6) is bonded in a 5-coordinate geometry to one Cs(1), one Cs(2), one Sb(2), one Sb(3), and one Sb(4) atom.