From lab to fab: how must the polymer solar cell materials design change? - an industrial perspective

Organic photovoltaic (OPV) devices, in particular polymer solar cells, made by solution processed organic materials have shown great promise as a disruptive technology for affordable electricity. Even though recent advances look impressive on paper, until now the commercialization of OPV has been hampered by the difficulty of converting lab produced "champion" cell figures into reliable industrial-scale product performances. A key factor to achieve this condition is to develop OPV materials (polymer donors, acceptors, buffer materials, electrodes materials and encapsulants) exhibiting the required technical and economic characteristics to be conveniently used in an industrial environment. The well established strategies for the design of materials for efficient lab-scale OPV devices are not sufficient when largearea printed panels are concerned. A number of additional requirements, normally not addressed in the laboratory context, must be met: the materials must be easily accessible as pure compounds in few synthetic steps from cheap starting compounds, need to be stable and soluble enough to afford ink formulations processable with roll-to-roll compatible equipment; solvent and solvent additives should be easily removable after printing, and possibly should be environmentally friendly compounds; the layers should achieve a stable morphology under mild conditions (low temperatures and short times); the above mentioned materials can be screened on glass substrates, but should be finally tested on plastic films, protected through a scalable encapsulation technique. The more researchers adhere to these guidelines, the greater the possibility for OPV to demonstrate at last its enormous potential on the industrial scale.