Because of both its easy processability and
compatibility with roll-to-roll processes, polymer electronics is
considered to be the most promising technology for the future
generation of low-cost electronic devices such as light-emitting
diodes and solar cells. However, the state-of-the-art deposition
technique for polymer electronics (spin-coating) generates a
high volume of chlorinated solution wastes during the active
layer fabrication. Here, we demonstrate that devices with
similar or higher performances can be manufactured using the
push-coating technique in which a poly(dimethylsiloxane)
(PDMS) layer is simply laid over a very small amount of solution (less than 1?L/covered cm2
), which is then left for drying.
Using mm thick PDMS provides a means to control the solvent diffusion kinetics (sorption/retention) and removes the necessity
for additional applied pressure to generate the desired active layer thickness. Unlike spin-coating, push-coating is a slow drying
process that induces a higher degree of crystallinity in the polymer thin film without the necessity for a post-annealing step. The
polymer light-emitting diodes and solar cells prepared by push-coating exhibit slightly higher performances with respect to the
reference spin-coated devices, whereas at the same time reduce the amounts of active layer materials and chlorinated solvents by
50 and 20 times, respectively. These increased performances can be correlated to the higher polymer crystallinities obtained
without applying a post-annealing treatment. As push-coating is a roll-to-roll compatible method, the results presented here open
the path to low-cost and eco-friendly fabrication of a wide range of emerging devices based on conjugated polymer materials.