Structural Evolution During Perovskite Crystal Formation and Degradation: In Situ and Operando X‐Ray Diffraction Studies

Mundt, Laura E.; Schelhas, Laura T.

doi:10.1002/aenm.201903074

Cited by 40 publications

(31 citation statements)

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“…While there are several reports on phase transformations and identification 20,21,28,60 , detailed insights into the phenomena occurring at critical synthesis and phase transition stages are desirable. Importantly, the kinetic processes occurring during nucleation and dissolution-recrystallization have not been revealed in detail so far, and are the focus of the present study (Fig.…”

Section: Discussionmentioning

confidence: 99%

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

et al. 2021

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Complex phenomena are prevalent during the formation of materials, which affect their processing-structure-function relationships. Thin films of methylammonium lead iodide (CH3NH3PbI3, MAPI) are processed by spin coating, antisolvent drop, and annealing of colloidal precursors. The structure and properties of transient and stable phases formed during the process are reported, and the mechanistic insights of the underlying transitions are revealed by combining in situ data from grazing-incidence wide-angle X-ray scattering and photoluminescence spectroscopy. Here, we report the detailed insights on the embryonic stages of organic-inorganic perovskite formation. The physicochemical evolution during the conversion proceeds in four steps: i) An instant nucleation of polydisperse MAPI nanocrystals on antisolvent drop, ii) the instantaneous partial conversion of metastable nanocrystals into orthorhombic solvent-complex by cluster coalescence, iii) the thermal decomposition (dissolution) of the stable solvent-complex into plumboiodide fragments upon evaporation of solvent from the complex and iv) the formation (recrystallization) of cubic MAPI crystals in thin film.

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Section: Discussionmentioning

confidence: 99%

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

et al. 2021

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“…[8,11,12] Thus, numerous works investigated the perovskite formation process using in situ characterization methods. [6,[13][14][15][16][17][18] Besides scattering techniques, [19][20][21][22][23][24] also optical spectroscopy, [25][26][27][28] with, e.g., absorption…”

Section: Introductionmentioning

confidence: 99%

Understanding Differences in the Crystallization Kinetics between One‐Step Slot‐Die Coating and Spin Coating of MAPbI₃ Using Multimodal In Situ Optical Spectroscopy

Schötz

Greve

Langen

et al. 2021

Advanced Optical Materials

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To develop a detailed understanding about halide perovskite processing from solution, the crystallization processes are investigated during spin coating and slot‐die coating of MAPbI3 at different evaporation rates by simultaneous in situ photoluminescence, light scattering, and absorption measurements. Based on the time evolution of the optical parameters it is found that for both processing methods initially solvent‐complex‐structures form, followed by perovskite crystallization. The latter proceeds in two stages for spin coating, while for slot‐die coating only one perovskite crystallization phase occurs. For both processing methods, it is found that with increasing evaporation rates, the crystallization kinetics of the solvent‐complex structure and the perovskite crystallization remain constant on a relative time scale, whereas the duration of the second perovskite crystallization in spin coating increases. This second perovskite crystallization appears restricted due to differences in solvent‐complex phase morphologies from which the perovskite forms. The work emphasizes the importance of the exact precursor state properties on the perovskite formation. It further demonstrates that detailed analyses of multimodal optical in situ spectroscopy allows gaining a fundamental understanding of the crystallization processes that take place during solution processing of halide perovskites, independent from the specific processing method.

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“…Many in situ XRD measurements have been performed recently to provide mechanistic insights in synthesis and degradation processes of halide perovskites. [24][25][26][27][28][29][30] Beyond synchrotron-assisted characterization, light, including monochromatic or certain parts of the spectrum, has been successfully used to probe optical properties, such as absorption and photoluminescence (PL) during synthesis. [31][32][33][34][35] To this end, in situ measurements have proven powerful for example, in revealing crystallization pathways, unveiling metastable phases, formation kinetics, and optimized annealing conditions.…”

Section: Introductionmentioning

confidence: 99%

The Value of Watching How Materials Grow: A Multimodal Case Study on Halide Perovskites

Sutter‐Fella

2021

Advanced Energy Materials

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natorial parameter spaces and real time control can change the way we are used to do material synthesis. Realizing this paradigm would not only speed up new materials discovery, shorten the development and optimization time of deploying new materials in commercial products by 10 times, [5] but also make better use of research resources. Toward this goal, further developments spanning new computational tools, materials databases, and synthesis and characterization techniques, need to converge. One approach to rationally synthesize materials, is to leverage in depth understanding of how complex materials assemble, how their properties evolve over time, and how this affects the overall physiochemical macroscopic properties. In fact, the mission innovation report recently identified the lack of structure-property relationships as one significant gap toward accelerated materials discovery using data-driven approaches. [6] Much of today's experiments are conducted by measuring single properties one by one ex situ, mostly near equilibrium. Ex situ measurements (referred to as "black box" synthesis) describe materials or device characterization post fabrication and do for example not allow for insights into crystallization pathways, chemical transformations, as well as the evolution or reciprocal correlation of functional properties that are happening dynamically over time during synthesis and device operation (Figure 1). Some experiments are conducted as break-off experiments where the synthesis is interrupted at different points during the reaction to conduct ex situ measurements and to capture snapshots of the reaction. More recently, in situ measurements are performed in real time as the material is synthesized, i.e., measurements are conducted during synthesis and one can monitor the possibly intricate interplay between thermodynamic and kinetically driven formation pathways. As an example, in situ diffraction measurements during synthesis that span several processing steps can reveal metastable crystalline phases that form as intermediates and then disappear at the end of the reaction. [7][8][9] With the beginning of modern science there has been a relationship between scientific discovery and innovative tools. Fast data collection was enabled by detector developments with integration times on the order of ≈ms and increasing X-ray fluxes available at synchrotron facilities. [10] These developments allow now to follow growth kinetics, structural transformations, and Material synthesis is one of the most important aspects in humankinds' endeavor to discover and create new materials for energy applications. One strategy to tailor materials with desired functions in a rational way is by knowing how functions relate to structure, synthetic variables, arrangement of atoms and molecules, and how functions evolve during synthesis. In order to accelerate materials synthesis, discovery, and optimization by 10 times it is the right time now to integrate computational tools, synthesis, and characterization. One particular barr...

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Structural Evolution During Perovskite Crystal Formation and Degradation: In Situ and Operando X‐Ray Diffraction Studies

Cited by 40 publications

References 93 publications

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

Understanding Differences in the Crystallization Kinetics between One‐Step Slot‐Die Coating and Spin Coating of MAPbI₃ Using Multimodal In Situ Optical Spectroscopy

The Value of Watching How Materials Grow: A Multimodal Case Study on Halide Perovskites

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Structural Evolution During Perovskite Crystal Formation and Degradation: In Situ and Operando X‐Ray Diffraction Studies

Cited by 40 publications

References 93 publications

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

Understanding Differences in the Crystallization Kinetics between One‐Step Slot‐Die Coating and Spin Coating of MAPbI3 Using Multimodal In Situ Optical Spectroscopy

The Value of Watching How Materials Grow: A Multimodal Case Study on Halide Perovskites

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Understanding Differences in the Crystallization Kinetics between One‐Step Slot‐Die Coating and Spin Coating of MAPbI₃ Using Multimodal In Situ Optical Spectroscopy