MAI (Methylammonium Iodide)

Order Code: M272
MSDS sheet

Price

(excluding Taxes)

£68.00


Methylammonium iodide (MAI) is a precursor for the synthesis of organic-inorganic hybrid perovskites for use in FETs, LEDs and PVs.

 Grade Order Code Quantity Price
98% purity M272 5 g £68
98% purity M272 10 g £113
98% purity M272 25 g £212
>99.9% purity M271 5 g £111
>99.9% purity M271 10 g £179
>99.9% purity M271 25 g £356

 Note: Looking for a bulk order (100 g or above of 98% or greater purity)? Please contact us for a quote.

 Applications

Due to the high purity of the methylammonium iodide (99.99%) it should be noted that there is a reduced solubility within dimethyl formamide and dimethyl sulfoxide. The reduced solubility is due to the removal of trace amounts of residual hydroiodic acid (HI) used during the synthesis and purification of the material. This reduced solubility can impact upon the performance of solar cells leading to a reduction in maximum power conversion efficiency achievable. The addition of fixed concentrations of hydroiodic acid to perovskite solutions can allow for the improvement of device metrics[1-3]. Using high purity precursor materials allows for accurate addition of amounts of hydroiodic acid giving higher reproducibility to experiments. It is recommended between 1% and 10% hydroiodic acid is used with high purity methylammonium iodide to achieve optimal device performance, the amount required is dependent upon the precursors used, solution concentration, solvent used, and processing environment therefore it will need to be tuned for each individual laboratory and process.

For simpler ink fabrication it is recommended that the lower purity methylammonium iodide (>98%) is used.

  1. Hysteresis-less inverted CH3NH3PbI3 planar perovskite hybrid solar cells with 18.1% power conversion efficiency, J. H. Heo et al., Energ. Environ. Sci., 8, 602-1608 (2015); DOI: 10.1039/C5EE00120J.
  2. A [2,2]paracyclophane triarylamine-based hole-transporting material for high performance perovskite solar cells, S Park et al., J. Mater. Chem. A., 3, 24215-24220 (2015); DOI: 10.1039/C5TA08417B.
  3. Enhanced optopelectronic quality of perovskite thin films with hydrophosphorous acid for planar heterojunction solar cells, W. Zhang et al., Nat. Commun.,  6,  10030 (2015);  doi:10.1038/ncomms10030.

Methyl-ammonium iodide (MAI) chemical structure
MAI chemical structure

 

Methylammonium iodide (MAI) photo
MAI powder

 

Specifications

Chemical formula CH6IN
CAS No. 14965-49-2
Chemical name Methylammonium iodide
Physical appearance White, crystalline solid
Purification method Recrystallisation (ethanol)
Purity >99.9% (as measured by elemental analysis)
Molecular weight 158.97 g/mol
Recommended solvents for perovskite synthesis DMF, DMSO

NMR spectrum

MAI 1H-NMR spectrum
1H NMR spectrum of methylammonium iodide in DMSO (500 MHz). The peaks centred around 2.5 and 3.3 ppm are residual DMSO and water impurities respectively from the deuterated NMR solvent. Click the image for a larger version.

 

Usage details

Reference devices - perovskite PVs

Reference devices were made to assess the performance of perovskite (MAI:PbCl2) based devices with the below structure. These were fabricated in air prior to spincasting the fullerene layer in a N2 glovebox. Substrates were then transferred to a vacuum chamber where a composite metal cathode was thermally evaporated. Finally, substrates were encapsulated inside the glovebox before measurements were taken under ambient conditions.

Glass / ITO (100 nm) / PEDOT:PSS (30 nm) / MAI:PbCl2 / PC70BM / Ca (5 nm) / Al (100 nm)

For generic details please see the fabrication guide and video. For specific details please see the below condensed fabrication report which details the optical modelling and optimisation of the multilayer stack.

The perovskite solution (MAI:PbCl2 at a molar ratio of 3:1) was made in dimethylformamide (DMF) at a concentration of 664 mg/ml. It was found to be critical that both materials were mixed dry prior to adding the solvent in order to achieve such high concentration.

For maximum efficiency, the active layer thickness was achieved from spincasting the heated solution (70°C) onto a hot PEDOT:PSS substrate (90°C) at a spin speed of 5000 rpm for 30s. The films were then placed back onto the hotplate (90°C) for 2 hrs. The data below shows the maximum performance achieved from non-optimised conditions.

Overall, the average efficiency after 5 mins light soaking was 8.89% (9.57% maximum) from MAI:PbCl2 based devices. Hysteresis was observed to be quite significant, with sweeps running from positive to negative bias presenting the best efficiencies (hereby referred to as reverse sweeps).

I101 perovskite ink J-V curve
Figure 1: JV curve under AM1.5 irradiation for a PV device based on MAI perovskite ink. Device characteristics were recorded on a reverse sweep.

 

I101 perovskite ink efficiency histogram
Figure 2: distribution in device efficiencies recorded for a typical process run. Data taken from 5 substrates containing 30 pixels. 10 pixels having low operational efficiency resulting from their proximity to the edge of the device substrate were removed from this analysis.

 

Fabrication

Substrates and cleaning

  • Pixelated Cathode substrates (S171) or Photovoltaic (8 Pixel) Substrates
  • 5 minutes sonication in hot 1% Hellmanex III
  • 1x boiling DI dump rinse, 1x cold dump rinse
  • 5 minutes sonication in warm IPA
  • 2x DI cold dump rinse
  • Stored in DI for 1hr
  • 5 minutes sonication in hot 10% NaOH solution
  • 2x DI dump rinse
  • N2 blow dry

PEDOT:PSS

  • PEDOT:PSS (Ossila M121 AI4083) filtered through a 0.45 µm PVDF filter
  • Spin on heated substrates at 6000 rpm for 30s
  • Bake at 130°C after spincast
  • Note that the cathode strip was not wiped clean, this is to allow a consistent perovskite layer on top
  • Substrates held at a temperature of 90°C for spincasting

Active layer solution

  • Old stock solution (2 weeks old) of MAI:PbCl2 (3:1 molar ratio) made at a concentration 664 mg/ml in DMF
    • Heated for approx. 3 hrs at 70°C
  • Old stock solution of PC70BM, 50 mg/ml in CB
    • Heated for approx. 4 hrs at 70°C with stirbar

Active layers

  • Devices spun onto hot substrate at 5000 rpm using 25 µl dynamic dispense for 30s
  • Placed immediately onto hotplate at 90°C for 2 hrs
  • Cathode wipe with dry cotton bud once all substrates were spun
  • Films started with a bright yellow colour
  • Changed to a dark grey colour during thermal annealing process
  • Transferred to a N2 glovebox
  • PCBM layer was spun at 1000 rpm for 30s, 20 µl dynamic dispense
  • CB cathode wipe

Evaporation

Left in vacuum chamber overnight and evaporated with the below parameters.

  • 5 nm Ca at 0.2 Å/s
  • 100 nm Al at 1.5 Å/s
  • Deposition pressure <1e-6 mbar="" li="">

Encapsulation

  • As standard using Ossila EE1, 30 mins UV in MEGA LV101

Measurements

  • JV sweeps taken with Keithley 237 source-meter
  • Illumination by Newport Oriel 9225-1000 solar simulator with 100 mW/cm2 AM1.5 output
  • NREL certified silicon reference cell used to calibrate
  • Lamp current: 7.8 A
  • Solar output at start of testing: 1.00 suns at 23°C
  • Solar output at end of testing: 1.00 suns at 25°C
  • Air cooled substrates
  • Room temperature at start of testing : 25°C
  • Room temperature at end of testing: 25°C
  • Calibrated aperture mask size: 0.256 mm2

We are continuously studying MAI and perovskites and expect to provide you with further information and optimised fabrication guides as we do so. Check back regularly or subscribe to our email newsletter for updates. In the meantime, please contact us if you have any further questions.

 

To the best of our knowledge the technical information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch