Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

Bai, Yang; Zhang, Xiao; Shang, Yuequn; Wang, Chenyue; Wang, Hao; Zhu, Cheng; Hu, Chen; Wu, Jiafeng; Zhou, Huanping; Li, Yujing; Yang, Shihe; Ning, Zhijun; Chen, Qi

doi:10.1002/ange.201914183

Cited by 27 publications

(6 citation statements)

References 50 publications

(37 reference statements)

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“…23 Recent work on the classical synthesis method has demonstrated the existence of an intermediate gel phase during growth. 42 This gel phase was identified as one of the processes that hinders the formation of homogenous 2D perovskite thin films. For film growths using the phase-selective method, the targeted n=3 2D perovskite phase formed relatively more quickly and continued growing over time as the amount of excess solution is consumed (Fig.…”

Section: Resultsmentioning

confidence: 99%

Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High‐Efficiency Devices

Sidhik

Samani

et al. 2021

Advanced Materials

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Two-dimensional (2D) perovskites are a class of halide perovskites offering a pathway for realizing efficient and durable optoelectronic devices. However, the broad chemical phase space and lack of understanding of film formation have led to quasi-2D perovskite films with polydispersity in perovskite layer thicknesses, which have hindered devices performance and stability. Here, we demonstrate a scalable approach involving dissolution of single-phase crystalline powders with homogeneous perovskite layer thickness in desired solvents, to fabricate 2D perovskite thin-films with high phase purity. In-situ characterizations reveal the presence of sub-micron-sized seeds in solution that preserve the memory of the dissolved single-crystals and dictate the nucleation and growth of grains with identical thickness of the perovskite layers in thin-films. Photovoltaic devices fabricated with such films, yields an efficiency of 17.1% and 1.20V open-circuit voltage, while preserving 97.5% of their peakperformance after 800 hours under illumination without any external thermal management.

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Section: Resultsmentioning

confidence: 99%

Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High‐Efficiency Devices

Sidhik

Samani

et al. 2021

Advanced Materials

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“…[ 39 ] The intensity distribution plots along the q z direction in Figure 3e reflects stronger detection of the PbI 2 phase in the target film than the control film, which may be due to secondary grain growth (induced by CF 3 BZAI passivators) or more severe out‐diffusion of the organic cations from the perovskite frameworks during high‐temperature (150 °C) annealing. [ 40,41 ] Overall, the GIWAXS results are well correlated to the XRD results.…”

Section: Resultsmentioning

confidence: 59%

Intercalation of Ammonium Cationic Ligands Enabled Grain Surface Passivation in Sequential‐Deposited Perovskite Solar Cells

Lee

Kumar

Cho

et al. 2022

Adv Energy and Sustain Res

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Solution‐processed formamidinium lead iodide (FAPbI3) perovskite typically contains a high number of ionic defects that are intrinsically formed during film formation. To reduce the defects, postsynthetic surface passivation treatment is widely practiced. However, the practicality of the surface passivation approach is limited by the poor coverage and incomplete adsorption of passivators into the defective sites. Unprecedentedly, the use of 4‐(trifluoromethyl)benzylammonium iodide (CF3BZAI) is demonstrated as a novel passivator additive for sequentially deposited perovskite films. Due to its unique molecular structure and trifluoromethyl (–CF3) moiety, CF3BZAI is expected to have enhanced adsorption with defect sites during the film formation. Owing to grain surface passivation, the CF3BZAI‐intercalated FAPbI3 (target) film has enhanced morphology and crystallinity as well as significantly fewer defects than the normal FAPbI3 film. Interestingly, the intercalation of CF3BZAI passivators does not lead to the formation of a low‐dimensional perovskite phase in FAPbI3 films. The best perovskite solar cell (PSC) device based on the target film achieves a maximum efficiency of ≈22.4%, which is much higher than the efficiency (≈20.7%) of the normal device. CF3BZAI‐assisted grain surface passivation is a facile yet effective strategy to enhance the performance and stability of FAPbI3‐based PSCs.

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“…The phase distribution is related to the crystallization process. After spin-coating, the precursor solution deposited on the substrate becomes a sol–gel intermediate state. , Upon postannealing, crystallization is initiated at the air–liquid interface where 3D domains crystallize first. − After that, the 3D nuclei serve as a template to guide the crystallization process downward into the bulk of the film, and the competition between consumption by large spacers and small cations leads to a phase distribution inside the film. The agglomeration of the large organic spacer at the bottom of the intermediate liquid due to its relatively heavier mass/lower mobility leads to the 2D low- n domains formation only toward the end of the crystallization process .…”

Section: Resultsmentioning

confidence: 99%

Manipulation of Crystal Orientation and Phase Distribution of Quasi-2D Perovskite through Synergistic Effect of Additive Doping and Spacer Engineering

Zhang,

Einhaus,

Huijser

et al. 2024

Inorg. Chem.

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The diammonium precursor 1,4-phenylenedimethanammonium (PDMA) was used as a large organic spacer for the preparation of Dion−Jacobson-type quasi-2D perovskites (PDMA)(MA) n−1 Pb n I 3n+1 (MA = methylammonium). Films with composition ⟨n⟩ = 5 comprised randomly orientated grains and multiple microstructural domains with locally differing n values. However, by mixing the Dion−Jacobson-type spacer PDMA and the Ruddlesden−Popper-type spacer propylammonium (PA), the crystal orientation in both the vertical and the horizonal directions became regulated. High crystallinity owing to well-matched interlayer distances was observed. Combining this spacer-engineering approach with the addition of methylammonium chloride (MACl) led to full vertical alignment of the crystal orientation. Moreover, the microstructural domains at the substrate interface changed from low-n (n = 1, 2, 3) to high-n (n = 4, 5), which may be beneficial for hole extraction at the interface between perovskite and hole transport layer due to a more finely tuned band alignment. Our work sheds light on manipulating the crystallization behavior of quasi-2D perovskite and further paves the way for highly stable and efficient perovskite devices.

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Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage

Cited by 27 publications

References 50 publications

Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High‐Efficiency Devices

Memory Seeds Enable High Structural Phase Purity in 2D Perovskite Films for High‐Efficiency Devices

Intercalation of Ammonium Cationic Ligands Enabled Grain Surface Passivation in Sequential‐Deposited Perovskite Solar Cells

Manipulation of Crystal Orientation and Phase Distribution of Quasi-2D Perovskite through Synergistic Effect of Additive Doping and Spacer Engineering

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