A review of polytypism in lead iodide

Beckmann, Peter A.

doi:10.1002/crat.201000066

Cited by 107 publications

(121 citation statements)

References 37 publications

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“…Peak (1) is assigned to a different PbI 2 variant, whose identifi cation is beyond the scope of this report in view of the large number of polytypes that have been reported for PbI 2 . [ 7,25 ] We then study the surface and cross-sectional morphology of C-PbI 2 and SAP-PbI 2 fi lms. As shown in Figure 2 , the conventional PbI 2 forms layered, dense, and non-uniform crystals.…”

Section: Resultsmentioning

confidence: 99%

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Zhang

Mao

et al. 2015

Advanced Energy Materials

244

137

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to 20.1% [ 2,3 ] within fi ve years. The theoretical limit of the PVSC effi ciency has been estimated to be 31%, which is very close to the Shockley-Queisser limit (33%). [ 4 ] Perovskite deposition is crucial to produce high-effi ciency PVSCs. Generally, there are mainly three methods, including onestep solution spin-coating, vacuum vapor deposition, and two-step sequential deposition to prepare the hybrid perovskite fi lm. [5][6][7][8][9][10][11][12][13] Two-step sequential deposition has recently been reported, [ 7 ] which provides an effi cient and low-cost route to high-performance PVSCs.In a typical two-step sequential deposition of perovskites such as MAPbI 3 (MA = CH 3 NH 3 + ), PbI 2 is fi rst deposited on the substrate (mesoporous or planar scaffold) by spin-coating or vacuum evaporation, subsequently transformed into the perovskite (MAPbI 3 ) by exposing it to an anhydrous isopropanol (IPA) solution of MAI. For the two-step sequential deposition, the conversion and fi lm morphology of the fi nal perovskite fi lm strongly depend on the initial PbI 2 fi lm during the fi rst step of the process. [ 7,14,15 ] Conventionally, PbI 2 from dimethyl formamide (DMF) solution tends to form a layered and dense crystalline fi lm on a fl at substrate. However, the complete conversion of PbI 2 to perovskite on exposure to the MAI solution usually requires several hours. [ 7 ] However, this long reaction time in MAI solution could lead to the dissolution of perovskite fi lms. These drawbacks make it diffi cult to fabricate planar-structured PVSCs by sequential deposition method.Several strategies have been developed to solve this problem, including using elevated reaction temperature, [ 16,17 ] controlling the crystallization of PbI 2 by employing strong coordinative solvent of dimethyl sulfoxide [ 14 ] or using MAI vapor instead of MAI solution. [ 18 ] Recently, a cloudy PbI 2 fi lm prepared by gas-quenching treatment has been reported by Vak and co-workers, [ 19 ] which also enhances the conversion of PbI 2 to perovskites in the process of roll-to-roll fabrication. Zhao & Zhu [ 14 ] developed a new three-step sequential deposition process, where a unstable PbI 2 ·CH 3 NH 3 Cl precursor fi lm is fi rst deposited on the mesoporous TiO 2 substrate and followed by thermal decomposition to form PbI 2 fi lm; the PbI 2 fi lm The photovoltaic performance of perovskite solar cells (PVSCs) is extremely dependent on the morphology and crystallization of the perovskite fi lm, which is affected by the deposition method. In this work, a new approach is demonstrated for forming the PbI 2 nanostructure and the use of high CH 3 NH 3 I concentration which are adopted to form high-quality (smooth and PbI 2 residue-free) perovskite fi lm with better photovoltaic performances. On the one hand, self-assembled porous PbI 2 is formed by incorporating small amount of rationally chosen additives into the PbI 2 precursor solutions, which signifi cantly facilitate the conversion of perovskite without any PbI 2 residue. On the other hand, by...

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Section: Resultsmentioning

confidence: 99%

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Zhang

Mao

et al. 2015

Advanced Energy Materials

244

137

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“…The basic building block of the crystal structure is a near-octahedral [PbI 6 ] 4− unit, in which each Pb atom is surrounded by 6 I atoms. Interactions between the layers are of weak Van der Waals type; so, there are many ways of stacking the layers and hence many polytypes exist for this compound [7].…”

Section: Introductionmentioning

confidence: 99%

Growth and properties of lead iodide thin films by spin coating

et al. 2016

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Abstract. In this study, lead iodide (PbI 2 ) thin films were deposited on glass substrates by spin coating a solution of 0.2 M PbI 2 dissolved in dimethylformamide, varying the deposition time and the spin speed. The thickness of the thin films decreased with increase in spin speed and deposition time, as examined by profilometry measurements. The structure, morphology, optical and electrical properties of the thin films were analysed using various techniques. X-ray diffraction patterns revealed that the thin films possessed hexagonal structures. The thin films were grown highly oriented to [001] direction of the hexagonal lattice. Raman peaks detected at 96 and 136 cm −1 were corresponding to the characteristic vibration modes of PbI 2 . The X-ray photoelectron spectroscopy detected the presence of Pb and I with core level binding energies corresponding to that in PbI 2 . Atomic force microcopy showed smooth and compact morphology of the thin films. From UV-Vis transmittance and reflectance spectral analysis, the bandgap of the thin films ∼2.3 eV was evaluated. The dark conductivity of the thin films was computed and the value decreased as the deposition time and spin speed increased.

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“…23 PbI 2 films were prepared by vacuum deposition without a mesoporous TiO 2 layer and by spin coating with mesoporous TiO 2 . In the case of the PbI 2 films prepared by vacuum deposition, a spot pattern was observed (Figure 2a), indicating a crystal with its [0 0 1] axis along the normal direction.…”

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confidence: 99%

Crystallization Dynamics of Organolead Halide Perovskite by Real-Time X-ray Diffraction

et al. 2015

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We analyzed the crystallization process of the CH3NH3PbI3 perovskite by observing real-time X-ray diffraction immediately after combining a PbI2 thin film with a CH3NH3I solution. A detailed analysis of the transformation kinetics demonstrated the fractal diffusion of the CH3NH3I solution into the PbI2 film. Moreover, the perovskite crystal was found to be initially oriented based on the PbI2 crystal orientation but to gradually transition to a random orientation. The fluctuating characteristics of the crystallization process of perovskites, such as fractal penetration and orientational transformation, should be controlled to allow the fabrication of high-quality perovskite crystals. The characteristic reaction dynamics observed in this study should assist in establishing reproducible fabrication processes for perovskite solar cells.

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A review of polytypism in lead iodide

Cited by 107 publications

References 37 publications

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Growth and properties of lead iodide thin films by spin coating

Crystallization Dynamics of Organolead Halide Perovskite by Real-Time X-ray Diffraction

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A review of polytypism in lead iodide

Cited by 107 publications

References 37 publications

A Smooth CH3NH3PbI3 Film via a New Approach for Forming the PbI2 Nanostructure Together with Strategically High CH3NH3I Concentration for High Efficient Planar‐Heterojunction Solar Cells

A Smooth CH3NH3PbI3 Film via a New Approach for Forming the PbI2 Nanostructure Together with Strategically High CH3NH3I Concentration for High Efficient Planar‐Heterojunction Solar Cells

Growth and properties of lead iodide thin films by spin coating

Crystallization Dynamics of Organolead Halide Perovskite by Real-Time X-ray Diffraction

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Product

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A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells

A Smooth CH₃NH₃PbI₃ Film via a New Approach for Forming the PbI₂ Nanostructure Together with Strategically High CH₃NH₃I Concentration for High Efficient Planar‐Heterojunction Solar Cells