In Situ Observation of Crystallization Dynamics and Grain Orientation in Sequential Deposition of Metal Halide Perovskites

Meng, Ke; Wang, Xiao; Xu, Qiaofei; Li, Zhimin; Liu, Zhou; Wu, Luhua; Hu, Youdi; Liu, Ning; Chen, Gang

doi:10.1002/adfm.201902319

Cited by 62 publications

(70 citation statements)

References 47 publications

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“…The X-ray incident angle is set to 0.05° and 1° to probe the shallow surface and full-depth structures of the perovskite films, respectively. [39,40] The 2D GI-XRD patterns of the perovskite film taken at 1° are shown in Figure 1e-g. The GI-XRD pattern of the reference film exhibits the diffraction arcs corresponding to α-FAPbI 3 (at wavevector transfer q = 1.00, 1.41, and 1.73 Å −1 ) and a secondary phase (at q = 0.72 Å −1 ), consistent with the previous report.…”

Section: Resultsmentioning

confidence: 99%

“…When the X-ray incident angle is set to 0.05°, the crystallographic details of the perovskite films at shallow surface can be obtained. [39,40] Figure S2 (Supporting Information) shows the 2D GI-XRD patterns of the perovskite film taken at 0.05°. Apparently, the diffraction intensities of (PA) 2 FAPb 2 I 7 and (PDA) 3 Pb 2 I 10 are higher than those of α-FAPbI 3 .…”

Section: Resultsmentioning

confidence: 99%

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Interfacial Structure and Composition Managements for High‐Performance Methylammonium‐Free Perovskite Solar Cells

Qiao

Wang

et al. 2020

Adv Funct Materials

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The methylammonium (MA)-free perovskite solar cells (PSCs) have drawn broad attention due to their excellent thermostability. However, the efficiency of these devices is inferior to most state-of-the-art PSCs. Herein, the photovoltaic performance of the MA-free PSCs is enhanced by constructing interfacial capping layers with a pair of alkylammonium halides, n-propylammonium (PA) iodide and propane-1,3-diammonium (PDA) iodide. The structure and composition of the interfacial layers are comprehensively investigated and their correlation with the device performance is presented in terms of defect passivation efficacy, energy level alignment, and hydrophobicity for moisture resistance. The PSC devices based on the PAI and PDAI 2 treated MA-free perovskite films demonstrate better power conversion efficiencies (PCEs) and stabilities than the reference devices without the interfacial layers. Although the PAI-treated devices exhibit the highest PCE of 21.1%, the PDAI 2-treated PSCs demonstrate the exceptional thermal and humidity stabilities.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Interfacial Structure and Composition Managements for High‐Performance Methylammonium‐Free Perovskite Solar Cells

Qiao

Wang

et al. 2020

Adv Funct Materials

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“…and generally mixed compositions opens a wide field for formation studies. [27][28][29][30][31][32][33] Greco et al…”

Section: Shifting From Mapbi 3 To Other Compositions Such As Fapbi 3 mentioning

confidence: 99%

“…[33] A recent study of the FAPbI 3 formation during two-step deposition by Meng et al clearly identified the photo inactive δ-FAPbI 3 as an intermediate phase in the conversion of the PbI 2 and FAI precursor to the α-phase of FAPbI 3 , as can be seen from Figure 2 (a) for the in situ XRD data and (b) for the trends in the different phases. [31] One interesting finding in the analysis of processing conditions for mixed perovskite compositions is the correlation between composition and the processing window: Qin et al found that Cs-containing compositions are less sensitive to the timing of the antisolvent deposition and therefore allow for a broader time frame for optimal deposition time. [27] As aforementioned, the antisolvent method requires delicate timing for achieving high-quality MAPbI 3 films.…”

Section: Shifting From Mapbi 3 To Other Compositions Such As Fapbi 3 mentioning

confidence: 99%

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

Mundt

Schelhas

2019

Advanced Energy Materials

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This review provides an update on the progress in understanding formation and degradation mechanisms in halide perovskites for photovoltaic applications, as supported by in situ and operando X‐ray scattering techniques. The value of these real‐time analyses is particularly high for gaining insights into the structural evolution during crystal formation and decomposition upon exposure to external stress factors. This type of analysis reveals the pathways between starting and end points of a process rather than being limited to comparing states before and after the process. Special attention is put on the successful efforts toward upscaling including deposition techniques that are compatible to roll‐to‐roll processing. These processes are realized using fast annealing procedures. The development of these processes strongly benefited from in situ studies exploring the direct transition from precursor to perovskite without going through observable crystalline intermediate phases. A particular focus of this review is the benefit of using in situ and operando X‐ray scattering techniques to better understand and ultimately improve device stability. The difference between structural stability of thin films and structural stability under device operation is highlighted, convincingly demonstrating the indispensability of operando studies.

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“…[26] Meng et al employed in situ GIWAXS measurements to investigate the annealing process of the PbI 2 and the perovskite, and found that adding ions of Br − , Cl − and MA + could accelerate the perovskite crystallization speed and modulate crystal grain orientations. [27] However, in situ study of the whole two-step process, especially during the two spin-coating steps, has not been reported.…”

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confidence: 99%

Precise Control of Perovskite Crystallization Kinetics via Sequential A‐Site Doping

et al. 2020

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film deposition process to achieve desired morphology and microstructure. [2-6] Most of the high-efficiency PSCs were produced by either one-step or two-step fabrication methods. The very first MAPbI 3-based PSC was fabricated via a one-step spincoating process developed by Kojima et al. in 2009. [7] However, the one-step fabricated perovskite film typically exhibited a dendritic morphology with poor coverage. To address the morphology issue, a two-step spin-coating process was developed by Xiao et al. [8] and Im et al. [9] in 2014, which consisted of sequential depositions of an inorganic PbI 2 layer and an organic salt MAI. This two-step method gave rise to compact and pinhole-free MAPbI 3 perovskite films, significantly increasing the efficiency of MA-based PSCs to ≈17%. [9] In 2015, the record PCE received another boost through the development of a simpler antisolvent-assisted one-step method, which could form a very uniform perovskite thin film by promoting the crystallization process. [4,10] Meanwhile, MA cations were replaced by CH(NH 2) 2 + (FA) cations to improve the light Two-step-fabricated FAPbI 3-based perovskites have attracted increasing attention because of their excellent film quality and reproducibility. However, the underlying film formation mechanism remains mysterious. Here, the crystallization kinetics of a benchmark FAPbI 3-based perovskite film with sequential A-site doping of Cs + and GA + is revealed by in situ X-ray scattering and first-principles calculations. Incorporating Cs + in the first step induces an alternative pathway from δ-CsPbI 3 to perovskite α-phase, which is energetically more favorable than the conventional pathways from PbI 2. However, pinholes are formed due to the nonuniform nucleation with sparse δ-CsPbI 3 crystals. Fortunately, incorporating GA + in the second step can not only promote the phase transition from δ-CsPbI 3 to the perovskite α-phase, but also eliminate pinholes via Ostwald ripening and enhanced grain boundary migration, thus boosting efficiencies of perovskite solar cells over 23%. This work demonstrates the unprecedented advantage of the two-step process over the one-step process, allowing a precise control of the perovskite crystallization kinetics by decoupling the crystal nucleation and growth process.

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In Situ Observation of Crystallization Dynamics and Grain Orientation in Sequential Deposition of Metal Halide Perovskites

Cited by 62 publications

References 47 publications

Interfacial Structure and Composition Managements for High‐Performance Methylammonium‐Free Perovskite Solar Cells

Interfacial Structure and Composition Managements for High‐Performance Methylammonium‐Free Perovskite Solar Cells

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

Precise Control of Perovskite Crystallization Kinetics via Sequential A‐Site Doping

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