Halide perovskites: current issues and new strategies to push material and device stability

Abstract

This short review aims at summarizing the current challenges related to poor Perovskite Solar Cells (PSCs) stability which nowadays puts severe constrains on near future device commercialization. As a game changer in the field of photovoltaics (PVs), PSCs are highly efficient and cheap to fabricate. However, they suffer from poor long-term stability upon exposure to heat, moisture, oxygen and light, and combinations thereof. Poor device stability originates from intrinsic instability issues of the perovskite active layer itself, as well as extrinsic factors due to partial degradation of the layers composing the device stack. Here we briefly review the chemical and physical processes responsible for intrinsic material instability, and we highlight possible solutions to overcome it; we then consider the whole device, discussing properties and interactions of the stacked layers. Finally, particular emphasis is placed on the need of shared standards for stability tests, which should include detailed report on experimental conditions over a statistically significant number of samples, allowing for a direct comparison of results across different groups and fostering a rapid advance of our understanding of degradation mechanisms and of the solutions to overcome them.

Accelerated Thermal Aging Effects on Carbon‐Based Perovskite Solar Cells: A Joint Experimental and Theoretical Analysis

“…At a given illumination, the current/voltage relationship is given by Equation () derived from the Shockley equationwhere I L , I 0 , R S , R SH , q , n , k B , and T are the photocurrent, the saturation current of the diode, the series resistance, the shunt resistance, the electron charge, the ideality factor, the Boltzmann constant, and the temperature, respectively. It is worth recalling that the R SH is usually related to the leakage current across the surfaces involving pinholes, grain boundaries, and charge recombination processes, [ 3 ] and the R S is reflected in the voltage drops and related to the conductivity of the layers and interfaces. [ 22,23 ] The ideality factor is related to interfacial layers, transport, and recombination processes, directly affecting the R SH and V OC .…”

Organic Inorganic Perovskites: A Low-Cost-Efficient Photovoltaic Material

“…Therefore, stability issues must be reasonably dealt with before its actual use and commercialization [62]. Poor stability of PSCs is due to several affiliated factors resulting from exposure to moisture, oxygen, light, and heat [63,64].…”

“…In detail, perovskite forms hydrate complexes with water such as (CH 3 NH 3 ) 4 PbI 6 •2H 2 O and leaves out PbI 2 , which tend to crystallize, forcing the forward reaction. Moreover, MA + is slightly acidic and reacts with water to form volatile methylamine (CH 3 NH 3 ) and hydroiodic acid (HI), according to the following reaction (1): [63].…”

“…MAPbI 3 is basically unstable upon thermal stress which produces a discharge of I 2 and the presence of metallic Pb at 40°C in the dark [63]. This is produced by the decomposition reactions (2) and (3): Although reaction ( 3) is reversible at just 80-85°C, methylammonium iodide decomposes into more volatile compounds as represented by reactions (4) and (5): It was found that HI(g) and CH 3 NH 2(g) were dominant products during the decomposition of MAPbI 3 and only trace amounts of CH 3 I and NH 3 were found.…”

All‐Inorganic Cesium‐Based Hybrid Perovskites for Efficient and Stable Solar Cells and Modules

“…[2][3][4][5][6][7] However, hybrid perovskites face severe degradation issues under operative conditions, which stem from the (photo) chemical instability when exposed to moisture, oxygen, UV light, and heat. [8][9][10][11][12] Among other reasons, the presence of the hydrophobic organic cation, e.g., methylammonium, can accelerate the degradation path. [12][13][14] For this reason, a greater focus has been devoted to exploring inorganic elements to replace the organic cations, for instance, using cesium to form CsPbX 3 all-inorganic perovskites.…”