Formamidinium Iodide (FAI)

CAS Number 879643-71-7

Materials, Perovskite Materials, Perovskite Precursor Materials

Formamidinium Iodide (FAI) CAS 879643-71-7

Formamidinium iodide, precursor for optimum solar conversion efficiencies

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Formamidinium lead iodide (CAS number 879643-71-7) shows a narrower bandgap than the commonly used methylammonium lead iodide (1.48 eV compared to ~1.57 eV), and hence lies closer to that favourable for optimum solar conversion efficiencies. With an approach of FAPbI₃ crystallisation by the direct intramolecular exchange of dimethylsulfoxide (DMSO) molecules intercalated in PbI₂ with formamidinium iodide, device with performance over 20% has been fabricated.

Formamidinium Iodide (FAI) from Ossila was used in the high-impact paper (IF 9.229), Using Soft Polymer Template Engineering of Mesoporous TiO2 Scaffolds to Increase Perovskite Grain Size and Solar Cell Efficiency, Q. Lian et al., ACS Appl. Mater. Interfaces 12, 18578–18589 (2020); DOI: 10.1021/acsami.0c02248.

Specifications

CAS number	879643-71-7
Chemical formula	CH₅IN₂
Molecular weight	171.97 g/mol
Synonyms	FAI, Formamidine hydroiodide
Classification / Family	Perovskite precursor materials, Perovskite solar cells, OLEDs

Product Details

Purity

M552: 99.9% (ICP-OES)

M551: >99.9% (further purified by double recrystallisation from 99.9% grade in ethanol)

Melting point

242 °C

Colour

White powder/crystals

Chemical Structure

formamidinium iodide, fai — Chemical structure of formamidinium iodide (FAI); CAS No. 879643-71-7; chemical fomula CH₅IN₂.

MSDS Documentation

Formamidinium iodide MSDS sheet

Applications

Formamidinium lead iodide shows a narrower bandgap than the commonly used methylammonium lead iodide (1.48 eV compared to ~1.57 eV), and hence lies closer to that favourable for optimum solar conversion efficiencies [1]. Spin-coating the formamidinium iodide (FAI) plus PbI₂ precursor solution in N,N-dimethylformamide (DMF) initially resulted in discontinuous perovskite films. However, by adding a small amount of hydroiodic acid (HI) to the stoichiometric FAI, extremely uniform and continuous films were formed.

Controlled humidity is another deciding factor that affects the film morphology, crystallinity, and optical and electrical properties of FAPbI₃ [2]. 16.6% PCE was achieved with low relative humidity of 2%, with the device efficiency dropped to about half (8.6%) when the humidity was 40%.

Low-volatility additives such as FACl and MACl are good candidates for assisting in the crystallisation of phase pure α-FAPbI₃ via the formation of intermediate mixtures, which prohibits the crystallisation of the δ-FAPbI₃ phase [3]. It also has been observed that the black perovskite-type polymorph (α-phase), which is stable at relatively high temperatures (above 160 ^oC), turned into the yellow FAPbI₃ polymorph (δ-phase) in an ambient humid atmosphere. Results show that incorporation of MAPbBr₃ into FAPbI₃ stabilises the perovskite phase of FAPbI₃ and improves the power conversion efficiency of the solar cell to more than 18% under a standard illumination of 100 mW/cm² [4].

With an approach of FAPbI₃ crystallisation by the direct intramolecular exchange of dimethylsulfoxide (DMSO) molecules intercalated in PbI₂ with formamidinium iodide, device with performance over 20% has been fabricated [5].

Device structure	FTO/TiO₂/FAPbIBr₂/spiro-OMeTAD/Au [1]
J_SC (mA cm^-2)	23.3
V_OC (V)	0.94
FF (%)	65
PCE (%)	14.2

Device structure	FTO/TiO₂/(FAPbI₃)_0.85(MAPbBr₃)_0.15/PTAA/Au [4]
J_SC (mA cm^-2)	22.5
V_OC (V)	1.11
FF (%)	73.2
PCE (%)	18.4

Device structure	FTO/bl-TiO₂/mp-TiO₂/FAPbI₃(DMSO)/PTAA/Au [5]
J_SC (mA cm^-2)	24.7
V_OC (V)	1.06
FF (%)	77.5
PCE (%)	20.2

Pricing

Grade	Order Code	Quantity	Price
98% purity	M552	5 g	£130
98% purity	M552	10 g	£220
98% purity	M552	25 g	£300
>99.5% purity	M551	5 g	£200
>99.5% purity	M551	10 g	£330

Literature and reviews

Formamidinium lead trihalide: a broadly tunable perovskite for efficient planar heterojunction solar cells, G. E. Eperon et al., Energy Environ. Sci., 7, 982-988 (2014), DOI: 10.1039/C3EE43822H.
Controlled Humidity Study on the Formation of Higher Efficiency Formamidinium Lead Triiodide-Based Solar Cells, S. Wozny et al., Chem. Mater., 27 (13), 4814–4820 (2015), DOI: 10.1021/acs.chemmater.5b01691.
Additive-Modulated Evolution of HC(NH2)2PbI3 Black Polymorph for Mesoscopic Perovskite Solar Cells, Z. Wang et al., Chem. Mater., 27 (20), 7149–7155 (2015), DOI: 10.1021/acs.chemmater.5b03169.

Compositional engineering of perovskite materials for high-performance solar cells, N. Jeon et al., Nature 517, 476–480 (2015), doi:10.1038/nature14133.
High-performance photovoltaic perovskite layers fabricated through intramolecular exchange,
W-S. Yang et al., Science, 348 (6240), 1234-1237 (2015). DOI: 10.1126/science.aaa9272.
Temperature dependence of hole conductor free formamidinium lead iodide perovskite based solar cells, S. Aharon et al., J. Mater. Chem. A., 3, 9171-9178 (2015), DOI: 10.1039/C4TA05149A.
High-Efficiency Perovskite Solar Cells Based on the Black Polymorph of HC(NH2)2PbI3, J-W. Lee et al., Adv. Mater., 26: 4991–4998 (2014). doi:10.1002/adma.201401137.
Efficient hole-conductor-free, fully printable mesoscopic perovskite solar cells with a broad light harvester NH2CH=NH2PbI3, M. Hu et al., J. Mater. Chem. A, 2, 17115-17121 (2014), DOI: 10.1039/C4TA03741C.

Resources and Support

How to Make Efficient Perovskite Solar Cells in a Glove Box

Various other perovksites and transport materials, along with references and examples of their uses, can be found on our "Ultimate Guide to Perovskites" page - but we thought it would be useful to demonstrate an example of how to make a PSC (that can acheive over 19% PCE), from start to finish. We've also tried to include some helpful tips to perfect your technique.

Learn more...