How to Make Efficient Perovskites Solar Cells in a Glove Box
This video details how to make highly efficient perovskite solar cells using the Ossila I301 ink with the following device stack:
ITO-coated glass / SnO2 / I301 / Spiro-OMeTAD / Au
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.
Specifically, this guide details how to:
- Wash and prepare substrates for fabricating devices
- Create SnO2 ETL in air
- Deposit an I301 perovskite layer in the Ossila Glove Box
- Deposit a uniform Spiro-OMeTAD layer in the Ossila Glove Box
- Finish and test devices
Ossila products used in this video:
- UV Ozone Cleaner
- ITO Patterned Glass Substrates
- I301 perovskite precursor
- Glove Box
- Spin Coater
- Measurement Aperture Mask
- Busbar Deposition Mask
- Solar Cell IV Test System
The video transcript is contained below:
- Substrate cleaning:
- Rub ITO between (gloved) fingers with Hellmanex then thoroughly rinse with water to remove all trace of hellmanex from the substrates.
- Sonicate for a period of time (we reccommend 10+ minutes) in deionised water/hellmanex combination, then rinse with a lot of boiling DI water.
- Sonicate briefly or dunk rinse in DI water.
- Rinse and sonicate ITO for 15 minutes in isopropyl alcohol (IPA).
- For best device performance, rinse and sonicate for 15 minutes in Acetone and subsequently rinse and sonicate as above in IPA.
- Then, dry substrates using filtered compressed gas and place the ITO into the UV Ozone cleaner and clean for at least 15 minutes.
- SnO2 ETL deposition:
- Create a 3% dilution of SnO2 nanoparticles in DI water.
- Take substrate straight from UV Ozone to the spin coater and statically spin coat 50μl of SnO2 at 3000rpm for 30s.
- Using a cotton bud and DI water, pattern devices as necessary. (Details for patterning the 8 pixel devices used in this video can be found here)
- Anneal for 20-40 mins at 150°C.
- Perovskite deposition (in glove box):
- Transfer the substrates into an inert environment glove box.
- Filter perovksite precursor using a 0.2μl filter.
- Place substrates inside the spin coater and dispense 35 μl of I301 ink all accross the substrate.
- This deposition requires a 2 step spin programme. Firstly, 1000 rpm for 10s, then an secoond step of 3000 rpm for 28s.
- 18 seconds into the second spin step, dispense 100μl of antisolvent to quench the perovskite and leave to spin for a further 15s (the quenching should be done using a slow, continuous stream of solvent over at least 1 second).
- Place substrate back onto the hotplate at 130°C for 10 minutes.
- Spiro-OMeTAD deposition (in glove box):
- Prepare the following solutions:
- Spiro-OMeTAD at a concentration of 85-86 mg/ml in chlorobenzene
- Li-TFSI at a concentration of 500 mg/ml in acetonitrile
- TBP at a volumetric percentage of 98%.
- FK209 Co (III) TFSI at a concentration of 300 mg/ml in acetonitrile
- For 1ml of solution, dissolve 85mg of Spiro-OMeTAD (unsublimed) in 1ml of chlorobenzene and leave to sit for a couple of hours. (For reference 1ml will coat ~20 [2.0 x 1.5cm] substrates.)
- Add dopants to this solution in this order and dissolve for a full minute after each addition:
11μl of FK209 Co (III) TFSI.
- Filter solution using a 0.2μm filter.
- Place perovskite-coated substrate in the spin coater and start spinning at 4000 rpm for 30 seconds.
- During this, dynamically dispense 25 µl of the Spiro-OMeTAD solution onto the substrate to create a uniform layer with minimal pinholes or comets.
- Spiro-OMeTAD oxidation and anode deposition:
- Remove devices from the glove box and store in a dry place away from UV light overnight. This gives the spiro-OMeTAD layer to oxidise fully, improving device performance.
- Using tweezers or a razor, scratch away the perovskite and spiro-OMeTAD layer as before (see 8-pixel patterning guide for more information)
- Using thermal evaporation, deposit at least 75nm layer of gold through the appropriate aperture mask to define an active area for your device (we recommend the use of our 8-pixel busbar maskk for optimal device performance)
- Devices can be measured immediately after being taken out of the glove box, but a performance improvement of up to 3% has been seen if devices are left to rest in air for another 12 hours after gold deposition.
- Testing Devices + Tracking Performance
- Current-Voltage sweeps can be performed on a PSC to measure PCE, VOC, JSC and fill factor. In this video we use an automatic IV tester which cycles through different pixels, sweeps voltage and measures current automatically, and a Newport 92251A-1000 solar simulator. It is very important that this is regularly calibrated to ensure accurate measurement.
- Device area can be defined with a aperture mask of known area, such as our 8-pixel aperture mask. This is your "active area" so it is worth regularly measuring this area with an optical microscope to ensure this value is correct.
- To confirm that device hysteresis is not creating false efficiencies, fixed-power-point tracking can confirm a "stabilised" PCE of a device. Here, a device is held at it's maximum-power point voltage, and the PCE is tracked over periods of time (usually 1 minute)
- It is possible that device performance may improve over a number of days. We recommend storing these in a dry, dark place while testing every day for 3 or 4 days to find optimum performance.