X-ray stability and degradation mechanism of lead halide perovskites and lead halides

Svanström, Sebastian; García‐Fernández, Alberto; Sloboda, Tamara; Jacobsson, T. Jesper; Rensmo, Håkan; Cappel, Ute B.

doi:10.1039/d1cp01443a

Cited by 41 publications

(65 citation statements)

References 53 publications

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“…Therefore, such high carrier concentrations can promote degradation of the perovskite in ways distinct from those encountered under illumination at 1 sun (10 14 to 10 16 carriers cm -3 , mostly generated at band edge), likely aiding in the radiolysis of the organic cations in the perovskite. [50] The radiation hardness described here suggests good resilience of these materials to degradation from electron radiation in space. Assuming radiation damage of hybrid perovskite being dependent on the total dose rather than on the dose rate, [11,12] the critical fluence for electrons would be accumulated after around ≈2000 years in the Earth orbit or ≈200 years at harsher orbits like Jupiter (see Figure S21, Supporting Information).…”

Section: Resultsmentioning

confidence: 71%

“…In fact, the presence of the organic cation species at the A position has been proposed to trigger degradation processes toward PbI 2 as opposed to the Pb 0 , mostly only seen from inorganic compositions, as the organics can undergo radiolysis more easily than the Pb 2+ cation upon electron and X‐ray illumination. [ 22,50 ] Future work should focus on combining the microscopy techniques used here with the passivation strategies that have been successfully employed in halide perovskite semiconductors (passivation by coordinate bonding, ionic bonding, or chemical conversion), [ 51 ] to gain better understanding of the chemistry of passivation in hybrid halide perovskites. In fact, SED was recently used to understand the effect of surface‐bound passivation agents on the crystallinity of halide perovskites by means of octahedral tilting stabilization.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Unveiling the Interaction Mechanisms of Electron and X‐ray Radiation with Halide Perovskite Semiconductors using Scanning Nanoprobe Diffraction

et al. 2022

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The interaction of high‐energy electrons and X‐ray photons with beam‐sensitive semiconductors such as halide perovskites is essential for the characterization and understanding of these optoelectronic materials. Using nanoprobe diffraction techniques, which can investigate physical properties on the nanoscale, studies of the interaction of electron and X‐ray radiation with state‐of‐the‐art (FA0.79MA0.16Cs0.05)Pb(I0.83Br0.17)3 hybrid halide perovskite films (FA, formamidinium; MA, methylammonium) are performed, tracking the changes in the local crystal structure as a function of fluence using scanning electron diffraction and synchrotron nano X‐ray diffraction techniques. Perovskite grains are identified, from which additional reflections, corresponding to PbBr2, appear as a crystalline degradation phase after fluences of 200 e− Å−2. These changes are concomitant with the formation of small PbI2 crystallites at the adjacent high‐angle grain boundaries, with the formation of pinholes, and with a phase transition from tetragonal to cubic. A similar degradation pathway is caused by photon irradiation in nano‐X‐ray diffraction, suggesting common underlying mechanisms. This approach explores the radiation limits of these materials and provides a description of the degradation pathways on the nanoscale. Addressing high‐angle grain boundaries will be critical for the further improvement of halide polycrystalline film stability, especially for applications vulnerable to high‐energy radiation such as space photovoltaics.

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 99%

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Unveiling the Interaction Mechanisms of Electron and X‐ray Radiation with Halide Perovskite Semiconductors using Scanning Nanoprobe Diffraction

et al. 2022

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“…Early studies using x-ray diffraction on thin films and synchrotron x-ray powder diffraction showed conflicting results on whether CH 3 NH 3 Pb(I 1-x Br x ) 3 exhibits full miscibility or not [27]. While the conflicting evidence may be related to the different excitation intensity of the light source [28], the question of whether these systems exhibit full miscibility in the dark at room temperature is still open. The additional uncertainty on the structural reversibility of these systems upon photo de-mixing and dark re-mixing complicates the matter.…”

Section: Photo De-mixing In Mixed Halide Perovskitesmentioning

confidence: 99%

Photo de-mixing in mixed halide perovskites: the roles of ions and electrons

et al. 2022

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Mixed halide perovskites have attracted great interest for applications in solar cells, light emitting diodes and other optoelectronic devices due to their tunability of optical properties. However, these mixtures tend to undergo de-mixing into separate phases when exposed to light, which compromises their operational reliability in devices (photo de-mixing). Several models have been proposed to elucidate the origin of the photo de-mixing process, including the contribution of strain, electronic carrier stabilization due to composition dependent electronic energies, and light induced ionic defect formation. In this perspective we discuss these hypotheses and focus on the importance of investigating defect chemical and ion transport aspects in these systems. We discuss possible optoionic effects that can contribute to the driving force of de-mixing and should therefore be considered in the overall energy balance of the process. These effects include the selective self-trapping of photo-generated holes as well as scenarios involving multiple defects. This perspective provides new insights into the origin of photo de-mixing from a defect chemistry point of view, raising open questions and opportunities related to the phase behavior of mixed halide perovskites.

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“…Exposure to intense X-rays typically accelerates the decomposition of hybrid perovskites into Pb(0), I 2 , and organic degradation products. [51,52] This decomposition is characterized by a general but not immediate decrease of the overall intensity as well as broadening of the perovskite Bragg peaks. Stuckelberger et al have shown that the interaction of MAPbI 3 with 8 keV photons induces ionic diffusion, [53] which is most probably at the origin of the observed degradation upon increasing the radiation dose.…”

Section: Texture In Mapbi 3 Thin Layersmentioning

confidence: 99%

Microstructure of Methylammonium Lead iodide Perovskite Thin Films: A Comprehensive Study of the Strain and Texture

Medjahed

Zhou

Quiceno

et al. 2022

Advanced Energy Materials

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Controlling the microstructure of hybrid halide perovskite thin films is essential for optimizing their performance in optoelectronic devices. It is well established that the strain state of the perovskite layer affects its stability. Likewise, the orientation of the perovskite lattice is a determining parameter as these materials have shown pronounced anisotropies in their physical and mechanical properties. In this work, the authors focus on the understanding of the mechanisms that govern the strain and texture observed in MAPbI3 thin films deposited on various oxide substrates. A thorough study of the evolution of the strain of the perovskite layer upon cooling down to room temperature from the crystallization temperature (100 °C) shows an essentially relaxed behavior of the perovskite layers. This result contradicts the commonly accepted hypothesis according to which MAPbI3 layers synthesized above ambient temperature are strained due to the large mismatch in the thermal expansion coefficients of the perovskite and its substrate. The texture in MAPbI3 layers is investigated by means of synchrotron full‐field diffraction X‐ray microscopy. This technique allows the direct observation of the [hh0] and [00l]‐oriented domains at the origin of the observed textures, demonstrating both their twin and ferroelastic nature. The stability of the different domain orientations is investigated by DFT calculations, illustrating the determining role of the chemical environment at the film‐substrate interface. PbI2‐ terminated surfaces are found to favor the [hh0] orientations while for MAI‐terminated ones, both [hh0] and [00l] domains are equally stabilized. The different results constitute an important step of clarification and understanding from the perspective of controlling the microstructure of perovskite layers.

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X-ray stability and degradation mechanism of lead halide perovskites and lead halides

Abstract: Lead halide perovskites have become a leading material in the field of emerging photovoltaics and optoelectronics. Significant progress has been achieved in improving the intrinsic properties and environmental stability of...

Cited by 41 publications

References 53 publications

Unveiling the Interaction Mechanisms of Electron and X‐ray Radiation with Halide Perovskite Semiconductors using Scanning Nanoprobe Diffraction

Unveiling the Interaction Mechanisms of Electron and X‐ray Radiation with Halide Perovskite Semiconductors using Scanning Nanoprobe Diffraction

Photo de-mixing in mixed halide perovskites: the roles of ions and electrons

Microstructure of Methylammonium Lead iodide Perovskite Thin Films: A Comprehensive Study of the Strain and Texture

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