Formamidinium Iodide (FAI)

Order Code: M552
MSDS sheet

Price

(excluding Taxes)

£99.00


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. 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.

98% purity M552 5 g £99
98% purity M552 10 g £169
98% purity M552 25 g £299
>99.5% purity M551 5 g £156
>99.5% purity M551 10 g £249

General Information

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

98%

>99.5% (further purified by double recrystalisation from 98% grade in ethanol)

Melting point

242 °C

Colour White powder/crystals

Chemical Structure

chemical structure of formamidinium iodide (fai)

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

 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]

JSC (mA cm-2) 23.3
VOC (V) 0.94
FF (%) 65
PCE (%) 14.2
Device structure FTO/TiO2/(FAPbI3)0.85(MAPbBr3)0.15/PTAA/Au [4]
JSC (mA cm-2) 22.5
VOC (V) 1.11
FF (%) 73.2
PCE (%) 18.4
Device structure FTO/bl-TiO2/mp-TiO2/FAPbI3 (DMSO)/PTAA/Au [5]
JSC (mA cm-2) 24.7
VOC (V) 1.06
FF (%) 77.5
PCE (%) 20.2

 

Literature and reviews

  1. 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. 
  2. 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.
  3. 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.
  4. Compositional engineering of perovskite materials for high-performance solar cells, N. Jeon et al., Nature 517, 476–480 (2015), doi:10.1038/nature14133.
  5. 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.
  6. 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.
  7. 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.
  8. 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.