General Decomposition Pathway of Organic–Inorganic Hybrid Perovskites through an Intermediate Superstructure and its Suppression Mechanism

Abstract

Organic–inorganic hybrid perovskites (OIHPs) have generated considerable excitement due to their promising photovoltaic performance. However, the commercialization of perovskite solar cells (PSCs) is still plagued by the structural degradation of the OIHPs. Here, the decomposition mechanism of OIHPs under electron beam irradiation is investigated via transmission electron microscopy, and a general decomposition pathway for both tetragonal CH3NH3PbI3 and cubic CH3NH3PbBr3 is uncovered through an intermediate superstructure state of CH3NH3PbX2.5, X = I, Br, with ordered vacancies into final lead halides. Such decomposition can be suppressed via carbon coating by stabilization of the perovskite structure framework. These findings reveal the general degradation pathway of OIHPs and suggest an effective strategy to suppress it, and the atomistic insight learnt may be useful for improving the stability of PSCs.

Truth and Myth of Phase Coexistence in Methylammonium Lead Iodide Perovskite Thin Film via Transmission Electron Microscopy

“…Evidently, the single-crystal perovskite has been damaged by the electron beam. The structural evolution during the gradual decomposition from tetragonal MAPbI 3 to intermediate MAPbI 2.5 , and thence to hexagonal PbI 2 has been studied in detail by Chen et al [2,11] and their findings support our argumentation.…”

“…[10] The (100), ( 110 ) planes have been attributed to the electron-beam-decomposition intermediate MAPbI 2.5 . [2,11] We simulated the ED pattern of tetragonal MAPbI 3 and MAPbI 2.5 as shown in Figure 2. Comparing our results to Kim et al's, we find that the simulated ED pattern of tetragonal MAPbI 2.5…”

Transient Optical Properties of CsPbX3/Poly(maleic anhydride‐alt‐1‐octadecene) Perovskite Quantum Dots for White Light‐Emitting Diodes

“…[ 6–9 ] Researchers have made significant improvements in optimizing the physical properties of CsPbX 3 , such as increasing its quantum efficiency and stability, and also, the PL mechanism was investigated. [ 10–12 ] Now, the external quantum efficiency of CsPbBr 3 ‐based light‐emitting diode (LED) has been increased from 0.12% to 22%. [ 7,13 ] However, the perovskite QDs are sensitive to air and humidity, which limits their practical commercial applications.…”

Engineering bandgap of CsPbI3 over 1.7 eV with enhanced stability and transport properties

“…However, engineering CsPbI 3 perovskite with organic cations to improve its intrinsic stability is limited to only a few organic cations such as formamidinium (FA) ( Hazarika et al., 2018 ) and methylammonium (MA) ( Wang and Chen, 2016 ). MA and FA cations are inherently unstable in thermal and UV conditions, leading to the degradation of perovskite and the poor lifetime of the photovoltaic devices ( Chen et al., 2020b ; Juarez-Perez et al., 2016 ; Yang et al., 2019 ).…”