PEDOT:PSS Grades Explained: AI 4083, PH 1000, HTL Solar and How to Choose

PEDOT:PSS is the most widely used conductive polymer in organic electronics research. It comes as a water-based dispersion, so it is easy to spin coat without organic solvents. But "PEDOT:PSS" is not a single material: there are several grades whose conductivity differs by a factor of a million or more, each designed for a different job. Using the wrong grade is a common reason for devices that do not work.

This article explains what PEDOT:PSS is, how the AI 4083, PH 1000 and HTL Solar grades differ, and how to store, coat and choose them.

What PEDOT:PSS is

PEDOT (poly(3,4-ethylenedioxythiophene)) is a conjugated polymer that conducts electricity but is insoluble in water. PSS (polystyrene sulfonate) acts as the counter-ion and keeps PEDOT stably dispersed in water. The PEDOT to PSS ratio, particle size and additives determine the final properties: conductivity, work function and how well it wets a surface.

The three most used grades

The grades below are Clevios™ formulations available from Ossila, all with CAS 155090-83-8:

• AI 4083: hole transport layer. PEDOT:PSS 1:6 (w/w), deliberately low conductivity (0.0002 – 0.002 S/cm), with a deep work function of 5.0 – 5.2 eV and fine particles (D50 80 nm). Used as the hole transport layer in OPV, OLEDs and organic and inverted perovskite cells. The low conductivity is intentional: the layer carries holes vertically without shorting neighbouring pixels.
• PH 1000: transparent electrode. PEDOT:PSS 1:2.5 (w/w) with a work function of 4.8 – 5.0 eV. With 5% dimethyl sulfoxide (DMSO), dried coatings reach 850 S/cm, and with additives such as DMSO or ethylene glycol sheet resistance can fall to around 300 Ω/sq. Used to replace ITO, as semi-transparent top electrodes, FET top gates, or planarization layers over rough surfaces such as FTO.
• HTL Solar: for surfaces that are hard to wet. PEDOT:PSS 1:2.5 (w/w) with conductivity of 0.1 – 1.0 S/cm and a work function of 4.8 – 5.0 eV. Its main advantage is better wetting, which suits inverted OPV cells where PEDOT:PSS must be coated on top of a hydrophobic active layer.

Choosing quickly

• Need a hole transport layer on ITO for OPV, OLEDs or p-i-n perovskites? Choose AI 4083.
• Need a transparent electrode or a highly conductive layer? Choose PH 1000 with a conductivity-enhancing additive.
• PEDOT:PSS will not cover evenly because the layer below is hydrophobic? Choose HTL Solar.

Storage and handling

• Store at 3 – 5 °C and do not freeze; freezing damages the dispersion. Ossila bottles are light-resistant and fitted with a temperature indicator.
• It is acidic (pH around 1 – 2.5 depending on grade). Wear gloves and read the SDS. The acidity can also slowly etch ITO if the layer is left for long periods.
• Bring to room temperature and mix gently before use. Avoid vigorous shaking, which creates bubbles.

Spin coating PEDOT:PSS

1. Filter the dispersion with a syringe filter before dispensing to remove aggregates that cause film defects.
2. Prepare the substrate by sequential cleaning and UV ozone so that the water-based dispersion wets evenly.
3. Spin coat at a speed calibrated for the thickness you need. Check thickness with a profilometer and conductivity with a four point probe.
4. Anneal on a hotplate to drive off residual water before the next layer. Water left behind can damage the layers above.

Spin coating is covered in more detail in our spin coater guide, and perovskite stacks that use PEDOT:PSS in our perovskite solar cell guide.

PEDOT:PSS at AMI Scientific

Ossila PEDOT:PSS AI 4083, PH 1000 and HTL Solar in 100 ml packs, plus larger packs of AI 4083 and PH 1000, are listed in our PEDOT:PSS collection. For substrates and equipment, see ITO and FTO glass, spin coaters and OLED materials.

Tell us about your device and the function of the layer via WhatsApp and our team will help you pick the right grade and prepare a formal quotation for your institution.