SnI₄^2--based hybrid perovskites templated by multiple organic cations: Combining organic functionalities through noncovalent interactions

Two and more different organic cations have been incorporated within single-phase hybrid perovskite frameworks derived from SnI₄ ^2- layers. The single-crystal structure of (5FPEA· NEA)SnI₄, containing in 1:1 ratio the 2,3,4,5,6- pentafluorophenethylammonium (5FPEA) and 2-naphthyleneethylammonium (NEA) cations [C2/m, a = 37.040(7) Å, b = 6.161(1) Å, c = 12.345(3) Å, β = 101.84(3)°, and Z = 4], provides details of the packing and interaction of the two organic species confined within the inorganic sheets. Controlled crystallization from solutions suggests that the 1:1 ratio is thermodynamically favored, perhaps as a result of the fluoroaryl-aryl interaction between the two organic cations. Systems with other ratios of the above two cations, however, can be accessed as thin films by spin coating from organic solutions. Structure and property studies indicate that the ratio of the organic cations is in monotonic correlation with the spacing of the perovskite sheets as well as the exciton energy associated with the electronic band gap. This study provides a simple method of modifying the electronic properties and combining organic functionalities within hybrid perovskites-a method that is based on noncovalent interactions (i.e., physical combination) instead of the traditional organic synthesis.