In-Line Quality Control of Organic Thin Film Fabrication on Rigid and Flexible Substrates

Abstract

A major factor for the achievement of the required performance, efficiency and lifetime of organic electronic (OE) devices (Organic Photovoltaics—OPVs, Organic Light Emitting Diodes—OLEDs, etc.) is the quality control of the substrates, active layers, barrier materials and transparent electrode nanolayers that are used for the fabrication of these devices. The in-line optical characterization and modeling of the optical and electrical properties of the above nanolayers can give valuable information of the growth mechanisms and the structure-property relationships that can play a major role towards the optimization of the nanolayers performance. Also, the capability for in-line monitoring, at every single step, of the optical properties and the quality of the fabricated nanolayers, e.g. by roll-to-roll (r2r) process, will improve the process yield opening the way for the low cost fabrication of OE devices. In this chapter, we will discuss in detail the latest advances on the combination of optical sensing by Spectroscopic Ellipsometry with the processes (vacuum deposition, r2r printing) for fabrication of OE nanolayers and devices. These advances include the results of the determination of the optical constants, composition, refractive index, thickness with nm precision, stability and the uniformity of the OE nanolayers onto rigid (e.g. c-Si, glass) and flexible (as Polyethylene Terephthalate—PET) substrates.