Combined AFM, XPS, and contact angle studies on treated indium–tin-oxide films for organic light-emitting devices

In the present work, surface modifications were performed on the indium–tin-oxide (ITO) substrates and the treated ITO surface properties were investigated by different characterization techniques. AFM and XPS methods were applied to measure surface roughness and chemical composition, respectively. Standard goniometry was used to determine contact angle and to calculate surface energy. Experimental results show that the ITO surface properties are subjected to the treatment methods which lead the surface to a certain degree of changes. Wettability of the modified surfaces was then monitored as a function of time elapsed after treatment and quantified. Furthermore, the polymer light-emitting electrochemical cells (LECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized. We observe that the electrical and optical performances of the polymer LECs are affected by the treatment methods on the ITO surface which result in the modification of interface formation and electrical contact of the ITO substrate with the polymer blend in the polymer LECs.