<i>In situ</i> simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation

Alsari, Mejd; Bikondoa, Oier; Bishop, James; Abdi‐Jalebi, Mojtaba; Ozer, Lütfiye Yıldız; Hampton, Mark; Thompson, Paul; Hörantner, Maximilian T.; Mahesh, Suhas; Greenland, Claire; MacDonald, John Emyr; Palmisano, Giovanni; Snaith, Henry J.; Lidzey, David G.; Stranks, Samuel D.; Friend, Richard H.; Lilliu, Samuele

doi:10.1039/c7ee03013d

Cited by 80 publications

(92 citation statements)

References 51 publications

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“…In this regard, in situ techniques play a critical role in providing time‐resolved information on the evolution of halide perovskites under various synthetic conditions. Recent reported in situ studies making use of diffraction measurements, terahertz spectroscopy, Fourier transform infrared spectroscopy, UV–vis spectroscopy, simultaneous X‐ray scattering and device performance, transmission electron microscopy, and spectrally ambiguous photoluminescence (PL) correlated with ex situ device performance gradually shed light on halide perovskite formation and its evolving material properties as well as on device performance. Despite these advancements, critical insights into phase formation and evolution of film properties occurring during spin‐coating and immediately after deposition go unobserved during the ≈2–5 min wet film transfer time prior to commencing subsequent in situ studies.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Dynamics of Hybrid Metal Halide Perovskite Formation via Multimodal In Situ Probes

Song

Yuan

Mori

et al. 2019

Adv Funct Materials

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The exploration of the synthetic space of halide perovskites hinges on an enormous number of parameters requiring time-consuming experimentation to decouple and optimize. Here, the formation of the prototype material CH 3 NH 3 PbI 3 (MAPbI 3 ) is investigated at different time and length scales using multimodal in situ measurements to monitor the evolution of crystalline phases, morphology, and photoluminescence as a function of the lead precursors. Kinetically fast formation of crystalline precursor phases already during the spin-coat deposition is observed using lead iodide (PbI 2 ) or lead chloride (PbCl 2 ) routes. These precursor phases most likely template final MAPbI 3 film morphology. In particular, the emergence of the "needle-like" structure is shown to appear before film annealing. In situ photoluminescence measurements suggest nanoscale nucleation followed by rapid nuclei densification and growth. Using this multimodal in situ approach, different formation pathways can be identified either via precursor phases in the PbI 2 and PbCl 2 routes or direct perovskite formation from molecular building blocks as observed in the lead acetate (PbAc 2 ) route. Correlation of in situ results with photovoltaic device performance demonstrates the power of in situ multimodal techniques, paves the way to a fast screening of synthetic parameters, and ultimately leads to controlled synthetic procedures that yield high-efficiency devices.

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Section: Introductionmentioning

confidence: 99%

Revealing the Dynamics of Hybrid Metal Halide Perovskite Formation via Multimodal In Situ Probes

Song

Yuan

Mori

et al. 2019

Adv Funct Materials

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“…However, the precise solution‐to‐solid conversion of these advanced formulations is yet to be revealed, and their improved processability in the context of anti‐solvent dripping is yet to be quantified, let alone understood. Such knowledge potentially holds important clues to further progress in formulation engineering . To accurately describe the intermediate phases during spin‐coating, we adopt the Ramsdell notation, employed by Gratia et al For example, the well‐known yellow δ phase, called here the 2H phase, is a nonperovskite phase composed of pure hexagonal closed‐packed AX 3 layers, resulting in a 1D array of BX 6 face‐sharing octahedra.…”

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confidence: 99%

Kinetic Stabilization of the Sol–Gel State in Perovskites Enables Facile Processing of High‐Efficiency Solar Cells

et al. 2019

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With record power conversion efficiencies (PCE) close to 24%, perovskite solar cells (PSCs) hold great promise to combine high photovoltaic performance with low processing cost. [1][2][3][4] This combination can be ascribed to several factors, such as the remarkable optoelectronic properties of perovskites-evidenced by a sharp absorption onset, a small Urbach energy, and a low exciton binding energy-as well as the fact that perovskites use earth-abundant elements. [5][6][7] The organic-inorganic metal halide perovskites used in such devices feature the characteristic AMX 3 structure, where A is an organic or inorganic cation, most often methylammonium (CH 3 NH 3 + , MA + ), formamidinium (HC(NH 2 ) 2 + , FA + ), or cesium (Cs + ), M is a metal cation, such as Pb 2+ or Sn 2+ , and X is a monovalent anion (halide ion Cl, Br, or I). [8][9][10] Various deposition techniques have been developed to obtain polycrystalline perovskite films, including spin-, dip-, and blade-coating, as well as vacuumbased processes. [11,12] To date, one-step spin coating remains the most popular and facile implementation to fabricate high-quality hybrid perovskite thin films from solution. The device efficiency and stability are strongly dictated by the electronic properties and trap state densities in the perovskite film. These, in turn, are influenced by the film crystallization, its morphology, and the presence of defects and imperfections. [13,14] However, despite the simplicity of the one-step deposition, the exact mechanisms underlying the growth process, from precursor solution to solid-state film, and the crystallization mechanism within the sol-gel state, are still poorly understood. This lack of information is partially caused by the heavy reliance on post-deposition ex situ characterization methods to date. [15,16] Recently, in situ time-resolved grazing-incidence wide-angle X-ray scattering (GIWAXS) has emerged as a powerful technique to study the microstructural evolution from the solution-precursor to the solid state, revealing the crystallization behavior and formation of crystalline intermediates and byproducts. [17,18] Using in situ GIWAXS methods, the classic MAPbI 3 perovskite material has already been investigated; Gong and coworkers identified the Perovskite solar cells increasingly feature mixed-halide mixed-cation compounds (FA 1−x−y MA x Cs y PbI 3−z Br z ) as photovoltaic absorbers, as they enable easier processing and improved stability. Here, the underlying reasons for ease of processing are revealed. It is found that halide and cation engineering leads to a systematic widening of the anti-solvent processing window for the fabrication of high-quality films and efficient solar cells. This window widens from seconds, in the case of single cation/ halide systems (e.g., MAPbI 3 , FAPbI 3 , and FAPbBr 3 ), to several minutes for mixed systems. In situ X-ray diffraction studies reveal that the processing window is closely related to the crystallization of the disordered sol-gel and to the number of crystalline byprodu...

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“…16,17 Several studies have confirmed the presence of transient crystalline precursor species. [18][19][20][21][22][23] The structure of mixed halide precursors has not been clearly determined and their formation kinetics depend on the lead counterion in the precursor. 20,21,24,25 Furthermore, previous studies have established that the film formation is a kinetically trapped process, indicating that the reaction coordinates depend on the film processing route (e.g., drop casting, spin coating, blade coating).…”

Section: Context and Scalementioning

confidence: 99%

Scalable Fabrication of Perovskite Solar Cells to Meet Climate Targets

Bruening

Dou

Simonaitis

et al. 2018

Joule

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HIGHLIGHTSOur cost model shows competitive perovskite PV requires high-throughput processingWe replace conventional annealing with rapid thermal processing without PCE lossThe combination of RTA and blade coating establishes a scalable processing routeIn situ XRD reveals a perovskite conversion mechanism and role of intermediates Bruening et al., Joule SUMMARYCost modeling shows that high-throughput processing of perovskite solar cells is required not only to compete with incumbent technologies in terms of levelized cost of energy, but more importantly, it is the major enabling factor facilitating sustainable growth rates of solar cell manufacturing capacity commensurate with global climate targets. We performed rapid thermal annealing at bladecoating speed to quickly deposit and convert perovskite thin films for scalable manufacturing of perovskite solar cells. In situ X-ray diffraction during film deposition and thermal conversion gave insight into the formation of crystalline intermediates, essential for high-quality films. Parameters were optimized based on the in situ study, allowing perovskite films to be annealed within 3 s with a champion power conversion efficiency of 16.8%. This opens up a clear pathway toward industrial-scale high-throughput manufacturing, which is required to fulfill the projected photovoltaic installation rates needed to reach climate goals.

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In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation

Abstract: Simultaneous GI-WAXS diffraction patterns and JV measurement of IBC solar cells during in situ anneal.

Cited by 80 publications

References 51 publications

Revealing the Dynamics of Hybrid Metal Halide Perovskite Formation via Multimodal In Situ Probes

Revealing the Dynamics of Hybrid Metal Halide Perovskite Formation via Multimodal In Situ Probes

Kinetic Stabilization of the Sol–Gel State in Perovskites Enables Facile Processing of High‐Efficiency Solar Cells

Scalable Fabrication of Perovskite Solar Cells to Meet Climate Targets

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