Video: How to Filter PEDOT:PSS with a Rubber-Free Syringe and PVDF Filter
This video demonstrates how to filter PEDOT:PSS with an Ossila rubber-free syringe and a PES filter in preparation for spin coating onto a substrate.
The PEDOT:PSS layer performs three functions:
- Planerisation of the ITO surface
- Matching of the ITO interface energy with the active layer
- Acts as a hole only (electron blocking) transport layer.
Getting a high quality PEDOT:PSS film is critical for effective device performance and is often the most difficult part of device fabrication. PEDOT:PSS requires a pristine and hydrophilic surface in order to coat properly, which should have been achieved with the cleaning routine above. It is also critical to ensure that the active areas have not come into contact with any other surfaces as this will affect how well the ITO will spin.
The grade and composition of PEDOT:PSS is also very important. We use Heraeus CleviosTM P AI 4083 which is filtered prior to use through a 0.45 μm PES filter. Note that it is very important to use a rubber-free syringe as many rubbers are attacked by the acidic nature of the PEDOT:PSS.
PEDOT:PSS is typically used in perovskite, OPVs and OLEDs and is spin coated to produce a film thickness of around 40 nm. To minimise material use this can be done by pipetting 20 to 30 μl into the middle of a spinning substrate. After spinning has completed visually inspect the PEDOT:PSS films for defects and for best performance discard any substrates with imperfections near the active pixels.