Spray Coating for Polymer Solar Cells: An Up-to-Date Overview

Solution processing is the most appealing aspect of organic photovoltaic (OPV) devices. The possibility of printing low-cost, lightweight, and efficient polymer solar cells (PSC) is the commonly accepted paradigm associated with printable materials deposited as inks using solution-processing techniques. In addition to slot-die, serigraphy, and flexo/gravure printing, spray coating can be used for photo-active polymer blends, interface materials for hole and electron extraction, and electrodes. This technique is widely accepted in the industrial world as one of the most suitable for coating thin layers onto virtually any kind of substrate (e.g., glass, metal, plastic) with a degree of conformability insuperable by any other high-speed coating technique. We present the basic principles governing the mechanisms of atomization, the main techniques adopted for PSCs, the state of the art applications of spray coating for building up each layer of a PSC, and an overview of the perspectives for industrialization.