Investigation on Enhanced Moisture Resistance of Two-Dimensional Layered Hybrid Organic–Inorganic Perovskites (C₄H₉NH₃)₂PbI₄

Abstract

Here, we choose (C 4 H 9 NH 3 ) 2 PbI 4 to represent the two-dimensional layered hybrid organic−inorganic perovskites and investigate its excellent moisture resistance by theoretical analyses. (C 4 H 9 NH 3 ) 2 PbI 4 adsorbs H 2 O molecules easily on all surfaces. However, the most energetic surface, i.e., C 4 H 9 NH 3 -terminated surface, provides an energy barrier of 3.46 eV to prevent the penetration of H 2 O molecules, which is 1 order higher than the barrier in MAPbI 3 surface. This obstacle for the invasive H 2 O molecule comes from the methyl/ methylene radicals of C 4 H 9 NH 3 groups. These methyl/methylene radicals are chemically inactive and only generate repulsive interactions with the H 2 O molecule, leading to the outstanding moisture resistance of (C 4 H 9 NH 3 ) 2 PbI 4 . Herein, we propose a practical strategy to obtain good moisture-resistant perovskite solar cell materials, i.e., modulate the shape and symmetry of organic molecules in perovskites to let as many methyl radicals as possible prevent the penetration of adsorbed H 2 O molecules from the surface.

Role of Ligand–Ligand Interactions in the Stabilization of Thin Layers of Tin Bromide Perovskite: An Ab Initio Study of the Atomic and Electronic Structure, and Optical Properties

“…The electronic and optical properties of these 2D systems can be tailored by varying the thickness of the layers, 28−31 while the surfaces can be protected with hydrophobic bulky ligands that could make it difficult for water molecules to penetrate through the surface. 32 Therefore, these systems are very interesting, and it is important to understand their stability as well as the effects of ligands on the optical properties. The electronic properties and band gap of PAE 2 PbI 4 33 and its multilayers have been studied earlier in the search of its application in optoelectronic detection devices.…”

Role of Polycyclic Aromatic Alkylammonium Cations in Tuning the Electronic Properties and Band Alignment of Two-Dimensional Hybrid Perovskite Semiconductors

“…Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have recently attracted considerable research interest. − The unique photophysical properties induced by spatial and dielectric confinement effects make 2D HOIPs attractive for many optoelectronic applications, such as photovoltaics, light-emitting diodes (LEDs), and photodetectors. − Compared to their three-dimensional analogues, 2D HOIPs show improved stability and wider structural and chemical flexibility, , which enables the tuning of optoelectronic properties by modifying the layer thicknesses and the composition of organic and/or inorganic components. ,− …”

“…1−4 The unique photophysical properties induced by spatial and dielectric confinement effects make 2D HOIPs attractive for many optoelectronic applications, such as photovoltaics, light-emitting diodes (LEDs), and photodetectors. 5−13 Compared to their three-dimensional analogues, 2D HOIPs show improved stability and wider structural and chemical flexibility, 2,14 which enables the tuning of optoelectronic properties by modifying the layer thicknesses and the composition of organic and/or inorganic components. 4,15−22 Choosing appropriate organic cations can lead to optically activated charge separation between the organic molecules and the inorganic framework in the low-dimensional HOIPs; such charge separation in photovoltaics has long been sought after to reduce nonradiative recombination by separating electron and hole transport channels.…”

Study of Surface and Bulk Recombination Kinetics of Two-Dimensional Inorganic–Organic Hybrid Semiconductors under Linear and Nonlinear Femtosecond Transient Absorption Analysis

“…Increasing demand of hybrid materials due to their high efficiency and progressive stability have drawn major attention of researchers, which is an indicative of enormous applications in various optoelectronics and photonic devices. Inorganic–organic (IO) hybrid semiconductor materials are excellent due to high carrier mobility, longer diffusion length, and large extinction coefficients making their useful applications in LEDs, photo detectors, and various optoelectronics devices. − Two-dimensional (2D) IO hybrids from the (R-NH 3 ) 2 MX 4 class have alternate layers of inorganic and wider bandgap organic moieties, which form natural multiple quantum well (MQW) structures. − Due to quantum and dielectric confinement effects, strong room-temperature Mott-type excitons are observed in these naturally self-assembled MQWs − with manifold enhanced binding energies (∼200–250 meV) compared to the parent PbI 2 (∼23 meV). ,− These 2D materials have attracted more attention due to their better environment stability, moisture resistance, and fascinating crystal packing engineering, compared to its 3D counterpart of (R-NH 3 )­MX 3 . − Weak van der Waals interlayer forces and organic moiety conformation within the inorganic layers play a key role in their self-assembly process and further the formation of layered structures. , …”