Organometallic Approaches to Conjugated Polymers for Plastic Solar Cells: From Laboratory Synthesis to Industrial Production

An overview of the organometallic synthetic approaches to low-band-gap polymers for organic solar cells from 2008 to the present is reported. The key role of the synthetic methods in development of materials with increasing performances is outlined, with consideration not only of research laboratory criteria, but also of parameters relevant to mass production: synthetic complexity, amount and toxicity of reactants and by-products, and purification steps. The review is organized into sections covering the different organometallic polymerization reactions, also including olefin metathesis and the most recent results on direct arylation processes that appear particularly promising in terms of reduced synthetic complexity, costs, and byproducts. In the last section of the review, the discussed synthetic methods are reconsidered from the perspective of industrial scalability, which is one of the most critical issues for making OPV technology an effective route to solar energy exploitation. Interesting considerations are drawn on these basis, and directions for future developments in terms of requirements of the synthetic protocols are outlined.