Clevios™ dispersions and formulations can be coated or printed by various methods, e.g. spin-, slot-die-, spray-, dip-, gravure-coating, or screen-, and inkjet-printing etc. While ready-to-use ink or paste formulations are available for some methods, a product modification might be necessary for others, which our technical service group can support.
Spin-coating is a very common and versatile method to deposit thin layers of Clevios in the laboratory. The spin-coating process for Clevios is described here in more details:
The thickness of the Clevios™ P layer after spin-coating onto (ITO) glass is determined by several parameters:
- spin speed
- spin time
- design of the spin-coater
- substrate size and surface
- quality of the pre-conditioning of the substrate surface.
The pre-conditioning of the (ITO) glass strongly affects the ability to uniformly disperse Clevios™ P onto the substrate surface. Therefore, no general rule can be given to determine at what spin speeds specific layer thicknesses will result. To exemplify typically spin-curves various Clevios™ P types are spin-coated on ITO-coated glass substrates. The results are obtained on a spin-coater (Carl Süss® RC 8, equipped with a 3’’ gyrset-lid). The ITO-coated glass substrates of size 50 mm x 50 mm are first wet-cleaned and then surface activated for 15 min in a UV/ozone-chamber. About 1-2 ml of Clevios™ P is deposited onto the substrate by using a Pasteur pipette. The polymer dispersion is distributed manually across the entire substrate’s surface prior to spin-coating.
After spin-coating the wet films are baked on a hot-plate in air. Recommended baking temperatures and times: 200 °C for 5 min for the electronic grades, e.g. Clevios™ P AI4083, Clevios™ P CH8000 and other Clevios™ HIL types; 130 °C for 15 min for the high conductive grades, e.g. Clevios™ PH 1000, Clevios™ HIL-E, Clevios™ F ET or Clevios™ HIL 8.
- If wetting problems occur during application of the Clevios™ P dispersions, a maximum of 10 % w/w of isopropanol may be added. Alternatively, the addition of surfactants might improve wetting especially on hydrophobic surfaces.
- In OLEDs, Clevios™ P layers are typically 50-80 nm thick. Layer thickness should be optimized experimentally to achieve best light out-coupling and planarization. N and k data are available for most of the HIL types on request.
- All remaining/unused dispersion should be removed from the equipment after use to avoid corrosion and further particle contamination by dried dispersion.