Reduced Band Gap Hybrid Perovskites Resulting from Combined Hydrogen and Halogen Bonding at the Organic−Inorganic Interface

Abstract

Undistorted perovskite layers are formed in PbI4-based hybrid perovskites incorporating X−(CH2)2−NH3 + (X = Br, Cl) cations. The outstanding structural feature of these compounds is the result of halogen and hydrogen bonding at the organic−inorganic interface, leading to the absence of hydrogen bonds between equatorial iodine atoms of the perovskite layer and ammonium parts, these last being located out of perovskite layers. As a consequence, these red salts display a reduced band gap (2.2 eV) which is assigned to a more disperse HOMO band compared to other salts such as (I−(CH2)2−NH3)2PbI4.

Understanding Quantum Confinement of Charge Carriers in Layered 2D Hybrid Perovskites

“…[57,58] Alternatively, one could also increase the size of the Bloch function basis set, [46] use an empirical atomistic TB approach for heterostructures, [46,58] or consider the 2D hybrid crystal as a single composite material. [12,17,18] However, one may seek to keep the description as close as possible to the one that is widespread for conventional semiconductors and this will be addressed in the next section.…”

“…Variations of the energy gaps are mainly associated to lattice distortions. [12,17,18] These distortions are related to the chemical structure of the organic cations.…”

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).…”

A Switchable NLO Organic‐Inorganic Compound Based on Conformationally Chiral Disulfide Molecules and Bi(III)I5 Iodobismuthate Networks

“…[3] While the organic molecules in these structures bear crucial responsibility for the nonlinear optical properties, [4] most physical properties of these hybrids, e.g., semi-conductivity, [5] magnetism, [6] or luminescence, [7] mainly arise from the inorganic framework. In most cases, the inorganic network consists of M II/III X 6 (M II = Sn, Pb, Cu; M III = Bi, Sb; X = Cl, Br, I) octahedral entities which are well known to form clusters, [8] and 1D, [9,10] or 2D, [11] polymeric anions depending on the nature of the ammonium counter ion, whereby size, number of charge, and conformation thereof seem to be most important. [12]…”