Probe Decomposition of Methylammonium Lead Iodide Perovskite in N₂ and O₂ by in Situ Infrared Spectroscopy

Abstract

Packaging methylammonium lead iodide perovskite (MAPbI)-based solar cells with N or dry air is a promising solution for its application in outdoor photovoltaics. However, the effect of N and O on the decomposition chemistry and kinetics of MAPbI is not yet well-understood. With in situ Fourier transform infrared spectroscopy measurements, we show that the effective activation energy for the degradation of MAPbI in N is ∼120 kJ/mol. The decomposition of MAPbI is greatly accelerated by exposure to O in the dark. As a result of the synergistic effect between O and a HeNe laser (633 nm), the degradation rate is further increased with photon flux. This synergistic effect reduces the effective activation energy of degradation of MAPbI to ∼50 kJ/mol. The solid decomposition products after annealing in N and O at 150 °C or below do not have absorbance between 650 and 4000 cm.

Toward Highly Thermal Stable Perovskite Solar Cells by Rational Design of Interfacial Layer

“…Assuming that there are two parallel reactions during the decomposition process, we could fit the lnk-(1/T) data according to the Arrhenius equation:k=A1e−Ea1badbreak/RT+A2e−Ea2badbreak/RTwhere A and Ea are the pre-exponential factor and apparent activation energy for each decomposition process, R = 8.314 J/(mol∗K) is the gas constant, and T is the absolute temperature. Shown in Figure 2B and Table 1, an identical Ea 2 (169.7 kJ/mol) for MO-based and P-based perovskites was observed at high temperature region, which could be related to the bulk-dominated decomposition of perovskite (Smecca et al., 2016, Yu et al., 2017, Deretzis et al., 2015). This value is also consistent with the previous reported values obtained by different methods (Smecca et al., 2016, Yu et al., 2017, Deretzis et al., 2015).…”

“…Shown in Figure 2B and Table 1, an identical Ea 2 (169.7 kJ/mol) for MO-based and P-based perovskites was observed at high temperature region, which could be related to the bulk-dominated decomposition of perovskite (Smecca et al., 2016, Yu et al., 2017, Deretzis et al., 2015). This value is also consistent with the previous reported values obtained by different methods (Smecca et al., 2016, Yu et al., 2017, Deretzis et al., 2015). More importantly, the A 1 of MO-based perovskite (0.0595) is ∼6.8 folds higher than that of the P-based perovskite (0.0088), indicating significant enhancement in lower Ea (Ea 1 = 16.6 kJ/mol) process at lower temperature region for MO-based perovskite.…”

Chemical Analysis of the Interface between Hybrid Organic–Inorganic Perovskite and Atomic Layer Deposited Al2O3

“…The observed vibrational modes (summarized in Table 1) are in good agreement with those reported in literature. 34,41,43−45 The most intense vibrational mode is marked by the symmetric and asymmetric N–H stretching modes (associated with NH 3 + ) at 3132 and 3179 cm –1 , respectively. The absence of O–H stretching vibrations in the region of 3400–3700 cm –1 indicates the absence of hydroxyl species (water, hydrates and hydroxide) in our pristine perovskite films.…”

Influence of Electrical Traps on the Current Density Degradation of Inverted Perovskite Solar Cells

“…Many papers have reported on the stability of PSCs, especially the degradation sources and their effects on the device degradation [6,7,8]. Under exposure to ambient conditions (light, oxygen, moisture), by-products such as methylamine (CH 3 NH 2 ), lead iodide (PbI 2 ), and iodine (I 2 ) are formed as a result of perovskite decomposition [9,10,11,12]. These by-products have undesirable effects (e.g., ionic diffusion from the perovskite layer to other interlayers) on the device performance [13,14,15].…”