Preparation, deposition and characterization of TiOx layers for organic PLEDs, solar cells and PTFTs

Wide band gap materials like LiF are being used as electron/injection layers (EIL/ETL) in PLEDs, to improve their efficiency. Recently, another wide gap material, TiOx, is being studied as an alternative for these EIL/ETL layers. TiOx layers are also studied as optical spacer for PSCs. In this work, TiOx layers of different thickness were deposited by spin coating from a solution of titanium oxide gel using titanium isopropoxide as precursor. The preparation was adjusted to the local conditions of the laboratory and requirements to control film thickness. Films were characterized optically and electrically, being observed that in dependence on the preparation conditions and further dilution in ethanol, films of thickness in the range between 60 nm to more than 200 nm can be prepared. Thinner films show high current density, which in combination with the high energy gap and index of refraction of the material, can be used as electron injection/transport layer and as optical spacers. MIS capacitors using thicker films, greater than 200 nm, showed a dielectric constant greater than 12 and a critical electric field greater than 10⁵ V/cm, which indicates than the spin coated TiOx films prepared using the described sol-gel procedure can be used also as the dielectric material in MIS structures for PTFTs.