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Fapbi3 Cif File
Formamidinium lead iodide ( FAPbI3FAPbI sub 3 ) is a cornerstone of modern perovskite photovoltaics, primarily due to its narrow bandgap (
) which allows for broad absorption of the solar spectrum into the near-infrared. For researchers, the Crystallographic Information File (CIF) is the vital blueprint that translates these macroscopic properties into atomic-level spatial coordinates. The Role of the CIF in FAPbI3FAPbI sub 3 A CIF file for FAPbI3FAPbI sub 3 defines the spatial arrangement of the formamidinium ( ) cation, the lead ( Pb2+Pb raised to the 2 plus power ) cation, and the iodide ( I−I raised to the negative power ) anions. It provides critical parameters such as: Space Group: Identifies the symmetry (e.g., for the cubic Lattice Constants: Typically for the room-temperature cubic cell.
Atomic Coordinates: Specific x, y, z positions for each element within the unit cell. Structural Phases and Their Signatures
The usefulness of a specific CIF depends on the "phase" it represents. FAPbI3FAPbI sub 3
is notoriously polymorphic, transitioning between several states based on temperature and environment: Common Name Crystal System Space Group Significance -phase Black phase
The "photoactive" phase used in high-efficiency solar cells. -phase Yellow phase P63mccap P 6 sub 3 m c
The thermodynamically stable "non-perovskite" phase at room temperature. -phase Intermediate Tetragonal Occurs as the material cools below -phase Orthorhombic/Trigonal Emerges below with restricted cation motion. Challenges in Modeling: The FA Cation
Unlike the simpler cesium cation, the formamidinium (FA) molecule is a large, non-spherical organic cation. In a standard cubic CIF, the FA molecule often appears disordered because it rotates rapidly within the lead-iodide "cage". This requires researchers to choose between a "time-averaged" CIF (useful for standard XRD refinement) and a "frozen" or relaxed structure (often derived from DFT calculations) for modeling electronic band structures. Strategic Importance FAPbI3.cif - WMD-group/hybrid-perovskites - GitHub
Formamidinium lead iodide ( FAPbI3FAPbI sub 3 ) exists in two primary phases at room temperature: the photoactive cubic -phase and the non-perovskite hexagonal
-phase. A Crystallographic Information File (CIF) for this material must accurately define its unit cell parameters, space group, and atomic coordinates. 1. Identify the Phase and Space Group The first step is determining which phase of FAPbI3FAPbI sub 3 you need for your model.
-Phase (Black Phase): This is the high-temperature cubic phase, typically assigned to the (No. 221) space group.
-Phase (Yellow Phase): This is the thermodynamically stable hexagonal phase at room temperature, often assigned to the (No. 194) space group. 2. Set Lattice Parameters
The unit cell dimensions vary significantly between phases and temperatures: Cubic ( ): Single cell length and angles Hexagonal ( ): Lattice parameters are roughly 3. Define Atomic Coordinates Short Guide to CIFs - CCDC
For a solid feature in a FAPbI3 (Formamidinium Lead Iodide) CIF file, the
structure is the most critical for high-efficiency solar applications. 1. Key Structural Parameters (
The cubic phase is characterized by its high symmetry and corner-sharing octahedra. A standard CIF for this phase typically includes these parameters: Space Group (No. 221). Lattice Constant ( : Approximately Cell Angles Crystal System 2. Common CIF Data Entry
Below is a representative snippet of the atom site coordinates for a perfectly cubic cap F cap A cap P b cap I sub 3
structure at room temperature. Note that in refined CIFs, the organic cap F cap A raised to the positive power cation (Formamidinium) is often modeled as disordered due to its rapid rotation within the lead-iodide cage. Site Occupancy Source: Adapted from GitHub - WMD-group/hybrid-perovskites 3. Stability Considerations is the goal for performance, cap F cap A cap P b cap I sub 3 fapbi3 cif file
is metastable at room temperature and tends to transition to the (hexagonal, yellow, non-perovskite). ResearchGate FAPbI3.cif - WMD-group/hybrid-perovskites - GitHub
#====================================================================== # CRYSTAL DATA #------------------------------------------
A Crystallographic Information File (CIF) for Formamidinium Lead Iodide ( cap F cap A cap P b cap I sub 3
provides the digital blueprint of its atomic structure, which is essential for X-ray diffraction (XRD) analysis and density functional theory (DFT) simulations Common Crystal Phases of cap F cap A cap P b cap I sub 3 cap F cap A cap P b cap I sub 3
is highly polymorphic, meaning it can exist in several structural arrangements depending on temperature and stability: ) Phase (Black Phase): Structure: High-temperature cubic perovskite ResearchGate Space Group: Commonly assigned to Duke University Lattice Parameter: Approximately ResearchGate
This is the photoactive "champion" phase used in high-efficiency solar cells due to its ideal bandgap AIP Publishing ) Phase (Yellow Phase): Structure: Non-perovskite hexagonal ResearchGate Space Group: cap P 6 sub 3 m c Technische Universität Berlin - TU Berlin Characteristics:
Thermodynamically stable at room temperature but photo-inactive, often appearing as a degradation product of the AIP Publishing Where to Find/Download CIF Files You can obtain verified cap F cap A cap P b cap I sub 3 CIF files from these research databases:
How to run DFT calculations on lower-end PCs? (Free and Fast)
In this case, I downloaded the . cif file for FAPbI3 from here. STEP 2. Open Materials Cloud's QE input Generator and upload the . Saif Ahmed FAPbI3_tetragonal&cubic
Formamidinium lead iodide ( cap F cap A cap P b cap I sub 3 ) is a widely studied hybrid halide perovskite for high-efficiency solar cells. A CIF (Crystallographic Information File) for cap F cap A cap P b cap I sub 3
contains the essential geometric data to describe its crystal structure, including lattice parameters, space group, and atomic coordinates. cap F cap A cap P b cap I sub 3 Phases in CIF Data -Phase (Cubic): The photoactive "black phase" used in solar cells. Space Group: in some computational models). Lattice Constant: at room temperature. Characteristics: High symmetry with the cap F cap A raised to the positive power cation at the center of cap P b cap I sub 6 octahedra. -Phase (Hexagonal): The non-photoactive "yellow phase" that cap F cap A cap P b cap I sub 3 often degrades into at room temperature. Space Group: Structure: Non-perovskite arrangement where cap P b cap I sub 6 octahedra share faces instead of corners. ACS Publications Key Components of an cap F cap A cap P b cap I sub 3 A standard CIF for the cubic phase typically includes: Lattice Parameters: Defining the unit cell dimensions ( ) and angles ( Symmetry Information:
Specifies the space group to define how atoms are repeated throughout the crystal. Atomic Coordinates: Fractional positions for: Typically at Located at face-centered positions like Formamidinium ( cap F cap A Often represented by individual atoms at the center of the unit cell cap F cap A cap P b cap I sub 3
You can find and download established CIF files from repositories like: The Materials Project Provides computed structures and predicted properties. GitHub (Hybrid Perovskites)
Contains specific research-grade CIFs for cubic and tetragonal phases used in DFT simulations. Crystallography Open Database (COD) A standard resource for experimental crystal structures. specific atomic coordinates or visualizing a particular phase in software like VESTA? FAPbI3.cif - WMD-group/hybrid-perovskites - GitHub
Formamidinium lead iodide (FAPbI₃) is a highly prized hybrid organic-inorganic perovskite material used in high-efficiency solar cells. A CIF file (Crystallographic Information File) for FAPbI3FAPbI sub 3
is the standardized digital text file that contains its exact 3D crystal structure, atomic coordinates, and symmetry. FAPbI3FAPbI sub 3
has multiple structures depending on temperature, a "full text" or complete overview of its CIF data requires understanding its distinct polymorphic phases. 🔬 Core Crystallographic Phases of FAPbI3FAPbI sub 3 To work with a FAPbI3FAPbI sub 3 Formamidinium lead iodide ( FAPbI3FAPbI sub 3 )
CIF file, you must first determine which phase or polymorph you need for your simulation or X-ray diffraction (XRD) matching:
To get a high-quality CIF file for Formamidinium Lead Iodide (FAPbI3), the most reliable method is to pull from established crystallographic databases or community-shared repositories. Top Sources for FAPbI3 CIF Files
The Materials Project: This is the gold standard for DFT-calculated structures. You can find various phases of FAPbI3 (alpha, delta, etc.) by searching for the chemical formula on the Materials Project Explorer.
Crystallography Open Database (COD): A massive collection of experimental crystal structures. Search for "FAPbI3" or the elements to find entries like the cubic -phase or hexagonal -phase at the COD Search Page.
Materials Cloud: Often used by researchers to host specific simulation inputs. For example, some tutorials on Materials Cloud allow you to upload and visualize FAPbI3 structures for Quantum Espresso runs.
ResearchGate/GitHub: Many computational materials science groups host their specific optimized CIFs on GitHub or share them in response to ResearchGate threads regarding perovskite solar cells. Which Phase Do You Need?
When downloading, ensure you select the correct polymorph for your research:
-FAPbI3 (Black phase): The cubic perovskite structure (space group ) used for high-efficiency solar cells.
-FAPbI3 (Yellow phase): The hexagonal non-perovskite phase (space group P63mccap P 6 sub 3 m c
) that is thermodynamically stable at room temperature but photo-inactive.
Pro-Tip: Once you have the file, use VESTA or the Materials Cloud Visualizer to verify the bond lengths and octahedral tilting before running your simulations.
Do you need a specific lattice parameter or a version optimized for a particular DFT functional?
How to run DFT calculations on lower-end PCs? (Free and Fast)
A Crystallographic Information Framework (CIF) file for FAPbI₃ (Formamidinium Lead Iodide) contains the essential structural data—such as lattice parameters, space groups, and atomic coordinates—needed to model this solar cell material in software like VESTA or Materials Project. Key Phases and Their Structural Parameters
FAPbI₃ is polymorphic, meaning it exists in different crystal structures depending on temperature and stability conditions. Common Name Crystal System Space Group Lattice Constant ( -phase Black Perovskite ≈6.36is approximately equal to 6.36
>150∘is greater than 150 raised to the composed with power -phase Black Perovskite Tetragonal Intermediate -phase Yellow Non-Perovskite P63mccap P 6 sub 3 m c Stable at room temp Critical Information in the CIF A-Site Cation: The formamidinium ion is organic and planar. In the -phase, it is orientationally disordered within the octahedral cages.
Inorganic Framework: The framework consists of corner-sharing lead iodide octahedra. The bond lengths are typically around Phase Transition: The "yellow" URL: perovskite
-phase is the most common room-temperature form, but it is not photoactive for solar cells. Research often focuses on stabilizing the "black" -perovskite phase. Where to Find FAPbI₃ CIFs
You can download verified structural files from these major databases:
Materials Project: Provides computed and experimental data for the cubic and hexagonal phases.
Crystallography Open Database (COD): Contains experimental CIFs derived from published X-ray diffraction (XRD) studies.
GitHub Repository (WMD-group): Hosts specific refined CIF files for hybrid perovskites, including "perfect" cubic models for computational use.
How to run DFT calculations on lower-end PCs? (Free and Fast)
This is a complete structural definition for FAPbI3FAPbI sub 3
(Formamidinium Lead Iodide) in its most common high-temperature Alpha ( ) phase (Cubic,
This "feature" is formatted as a standard Crystallographic Information File (CIF) that you can copy into software like VESTA, CrystalMaker, or PyMaw. CIF File Content: FAPbI3FAPbI sub 3 (Cubic Phase)
data_FAPbI3_cubic _audit_creation_method 'Hand-generated for Cubic Alpha-Phase' _cell_length_a 6.3620 _cell_length_b 6.3620 _cell_length_c 6.3620 _cell_angle_alpha 90.00 _cell_angle_beta 90.00 _cell_angle_gamma 90.00 _cell_volume 257.49 _symmetry_space_group_name_H-M 'P m -3 m' _symmetry_Int_Tables_number 221 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Pb1 Pb 0.50000 0.50000 0.50000 1.0 I1 I 0.50000 0.50000 0.00000 1.0 C1 C 0.00000 0.00000 0.00000 1.0 N1 N 0.00000 0.00000 0.18000 0.5 Use code with caution. Copied to clipboard Key Technical Specs Structure: Perovskite ( ABX3cap A cap B cap X sub 3 Lattice Parameter: Å (varies slightly by temperature).
The "Organic" Challenge: In a standard CIF, the FA molecule is often represented by its central Carbon at the origin
. Because the molecule rotates rapidly at room temperature, it is often modeled with disordered Nitrogen sites or as a spherical density. Bandgap: Typically ∼1.48tilde 1.48
eV, making it the "Goldilocks" material for single-junction solar cells. Quick Usage Tips
Visualization: If you open this in VESTA, the FA molecule may look like a single atom at the corners. To see the full molecule, you often have to manually add the Hydrogen positions or use a lower-symmetry space group ( ) if you are running DFT simulations.
Phase Note: If your sample is yellow rather than black, you are likely looking for the Delta ( ) phase (Hexagonal, P63mccap P 6 sub 3 m c ), which is photo-inactive.
3. NREL’s Perovskite Database
- URL: perovskite.nrel.gov
- Use: Excellent for experimental lattice parameters extracted from literature.
Method C: Literature Extraction
The most accurate structural parameters often come directly from the seminal papers. The definitive structure was elucidated by researchers like M. Grätzel and colleagues.
- Key Reference: W. S. Yang et al., "High-performance photovoltaic perovskite layers fabricated through intramolecular exchange", Science (2015).
- Supplementary Materials: Always check the Supplementary Information (SI) of high-impact papers. They almost always contain the experimental CIF as a downloadable attachment.
Article: FAPBI3 CIF — Overview, Structure, and Usage
Example (simplified) CIF snippet for α-FAPbI3
data_FAPbI3_alpha
_chemical_name_common 'formamidinium lead iodide'
_chemical_formula_sum 'C H6 N2 Pb I3'
_cell_length_a 6.35
_cell_length_b 6.35
_cell_length_c 6.35
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_symmetry_space_group_name_H-M 'Pm-3m'
_symmetry_Int_Tables_number 221
loop_
_atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z
Pb1 Pb 0.0 0.0 0.0
I1 I 0.5 0.5 0.0
I2 I 0.5 0.0 0.5
I3 I 0.0 0.5 0.5
C1 C 0.5 0.5 0.5
N1 N 0.45 0.55 0.5
N2 N 0.55 0.45 0.5
Note: FA+ is often modeled with partial occupancy or split positions to reflect orientational disorder.
Part 8: Advanced Topics – Beyond the Basic CIF
The δ-Phase (Yellow, Non-Photoactive)
- Space Group: P6₃mc – Hexagonal.
- Lattice Parameters:
a ≈ 8.98 Å,c ≈ 11.41 Å. - Note: If you accidentally use the δ-phase CIF file for a simulation of an efficient solar cell, your bandgap calculation will be wrong. Always verify the phase.
Important Considerations
- Phase stability: Many CIFs available online are for the metastable α-phase at elevated temperatures. For RT simulations, you may need to use a tetragonal or experimentally stabilized structure.
- Disorder: FA cations often exhibit dynamic disorder, so some CIFs may show split atomic positions or partial occupancies.
- Validation: Always check the R-factors and data quality if the CIF comes from a published study.