Unique Hydrogen Bonding Correlating with a Reduced Band Gap and Phase Transition in the Hybrid Perovskites (HO(CH₂)₂NH₃)₂PbX₄ (X = I, Br)

Abstract

The first hybrid perovskites incorporating alcohol-based bifunctional ammonium cations, (HO(CH(2))(2)NH(3))(2)PbX(4) (X = I, Br), have been prepared and characterized. (HO(CH(2))(2)NH(3))(2)PbI(4) adopts a monoclinic cell, a = 8.935(1) A, b= 9.056(2) A, c = 10.214(3) A, beta = 100.26(1) degrees , V = 813.3(3) A(3), P2(1)/a, and Z = 2, and (HO(CH(2))(2)NH(3))(2)PbBr(4) is orthorhombic, a = 8.4625(6) A, b = 8.647(1) A, c = 19.918(2) A, V = 1457.5(2) A(3), Pbcn, and Z = 4. In the layered structures, a unique hydrogen-bond network connects adjacent perovskite layers, owing to OH....X, NH(3)(+)....X, and intermolecular NH(3)(+)...OH interactions. Its impact on the bonding features of the inorganic framework and on the quite short interlayer distance, in the case of (HO(CH(2))(2)NH(3))(2)PbI(4), is shown. As a result, a significant red shift of the exciton peaks (lambda = 536 nm (X = I), lambda = 417 nm (X = Br)), compared to other PbX(4)(2)(-)-based perovskite hybrids, is observed, revealing a reduced band gap. A reversible structural transition occurs at T = 96 degrees C (X = I) and T = 125 degrees C (X = Br). An orthorhombic cell of the high-temperature phase of (HO(CH(2))(2)NH(3))(2)PbI(4) with a(HT) = 18.567(6) A, b(HT) = 13.833(6) A, c(HT) = 6.437(2) A, and V = 1653 A(3) is proposed from powder X-ray diffraction. A change in the hydrogen bonding occurs, with molecules standing up in the interlayer space and OH parts probably interacting together, leading to a more conventional situation for ammonium groups and a more distorted perovskite layer. This is in accordance with the blue shift of the exciton peak to lambda = 505 nm (X = I) or to lambda = 374 nm (X = Br) during the phase transition.

A New Class of Nanostructured Inorganic–Organic Hybrid Semiconductors Based on II–VI Binary Compounds

“…The layered perovskite hybrid structures provide a good platform for the preparation and investigation of two-dimensional (2D) quantum well systems (89)(90)(91)(92). A number of interesting optical, electrical, and magnetic properties have been discovered in these materials (75,90,(93)(94)(95)(96)(97)(98)(99)(100)(101)(102)(103)(104)(105)(106)(107)(108).…”

Lead Halide Layers Linked by trans‐Cu(Gly)2 (Gly = –O2C–CH2–NH2) Pillars in Heterometallic Glycinate Based Organic–Inorganic Hybrids

“…This is made possible because of the incorporation of selected cations that are able to impact the bonding features of the inorganic framework. [5] Hybrids with enhanced structural dimensionality have also been considered. [6,7] In particular, we recently showed that in [Cu{O 2 C-(CH 2 ) 3 -NH 3 } 2 ]PbBr 4 the amino carboxylic acid zwitterionic molecules led both to the stabilization of a layered hybrid perovskite and to the formation of a Br-Cu-Cu-Br covalent bond pathway between adjacent perovskite layers.…”

Heterometal silver/copper(I) modulated thermochromism of two isostructural iodoplumbates

“…Although Pb is a neighboring element of Bi with similar cation size and octahedral coordination character [13,19], their different oxidation states endow them with specific structural buildings and functional features. Typically, thermochromism as an interesting phenomenon has attracted much attention in the field of iodobismuthate or iodoplumbate hybrids [8,12,[20][21][22][23][24][25][26][27]. Differing from the thermochromic iodobismuthates, only a handful of thermochromic layered perovskite-type iodoplumbates [22][23][24][25][26][27] and two thermochromic heterometallic iodoplumbates ([Co(phen) 3 ] 2 [Pb 3 Cu 6 I 16 ] Á C 2 H 5 OH [12] and [Pb 3 I 10 Cu 4 (phen) 2 ] n ) [8] have been reported, which is likely due to their larger energy gap and limited response of their structures to the temperature.…”

“…Typically, thermochromism as an interesting phenomenon has attracted much attention in the field of iodobismuthate or iodoplumbate hybrids [8,12,[20][21][22][23][24][25][26][27]. Differing from the thermochromic iodobismuthates, only a handful of thermochromic layered perovskite-type iodoplumbates [22][23][24][25][26][27] and two thermochromic heterometallic iodoplumbates ([Co(phen) 3 ] 2 [Pb 3 Cu 6 I 16 ] Á C 2 H 5 OH [12] and [Pb 3 I 10 Cu 4 (phen) 2 ] n ) [8] have been reported, which is likely due to their larger energy gap and limited response of their structures to the temperature. Although some explanations have been suggested for the above phenomenon, such as the temperature induced phase transition and lattice contraction, this kind of thermochromic property can generally be attributed to the distortion of iodoplumbate framework and consequent changes of absorption position and intensity, which implies the decisive roles of chain-like organic amines and heterometallic components.…”