Crystal structural and thermochromic luminescence properties modulation by ion liquid cations in bromoplumbate perovskites

The present work deals with three one-dimensional (1D) bromoplumbate perovskites, namely [C-4-Mim] [PbBr3] (1), [C-5-Mim] [PbBr3] (2) and [C-6-Mim] [PbBr3] (3) (where C-4-Mim(+) = 1-butyl-3-methylimidazolium, C-5-Mim(+) = 1-pentyl-3-methylimidazolium, C-6-Mim(+) = 1-hexyl-3-methylimidazolium). 1D inorganic chain is built from corner-sharing PbBr6 octahedron in three compounds. 1 crystallizes in chiral space group P2(1)2(1)2(1) at 100 K. 2 and 3 crystallizes in the same monoclinic crystal system P21/n at 100 K. Three compounds have low melting point compared to reported haloplumbates organic-inorganic perovskites, and the melting point of is 98 degrees C for 1, 102 degrees C for 2, and 113 degrees C for 3. Interestingly, three compounds show multi-band emission and exhibits fascinating thermochromic luminescent properties.