4.17 - Polymer solar cell fabrication using spray coating

Abstract

Although polymer solar cells are inexpensive, lightweight, easily assembled, scalable, and environmentally benign, their efficiency is significantly lower than that of other solar cells now on the market. The capacity to produce polymer solar cells (PSC) at a reasonable cost and on a large scale remains a fundamental challenge. Because PSC manufacture mostly requires a vacuum atmosphere, which is an expensive endeavor, the facility for this procedure is currently somewhat remote. However, for a type of thin film solar cells where the components of the solar cell can be generated in a solution, more scalable and vacuum-free fabrication techniques are being developed. Examples of materials that could be handled in solutions are thin-film solar cells that contain all or some layers of polymer, dye-sensitized, quantum dot, and copper indium gallium selenide. After the solvent has evaporated, a thin layer will form on the substrate from the components that have undergone solution processing. This can be achieved by atomizing the solution and transferring the spray droplets to the substrate. Spray coating is a challenging fabrication approach, if it is possible to achieve reasonably uniform layers with high charge carrier separation and transport capabilities. This is because the coating is applied at atmospheric pressure using moderately priced equipment that can process rolls to rolls. Large scale production is possible by spray coating and few techniques are briefly discussed in this chapter.