Water-processable nanoparticle assemblies based on amphiphilic low band gap rod-coil block copolymers: a tool for active layers

Water-processable organic nanoparticles (NPs) of semiconducting polymers received wide attention for optoelectronic applications due to their simple fabrication and tunable properties. The NP-based approach is appealing to control the morphology of the active layer in optoelectronic devices, such as organic photovoltaics (OPVs), organic light-emitting diodes, and organic field-effect transistors. The miniemulsion method ensures the stability of the water-suspended NPs using insulating surfactants, lowering the chlorinated solvent use for the active layer fabrication. To gain good performances, the surfactant excess has to be removed at the end of the process. [Mater Today 2016, 19, 533] Here we will present a series of amphiphilic low band gap rod-coil block copolymers (BCPs), constituted by a low band-gap polymer, PCPDTBT as electron donor material, and different poly-4-vinylpyridine (P4VP)-based flexible blocks. We studied the capability of these BCPs, neat or in blend with electron acceptor materials, to assembly NP dispersions in aqueous medium through miniemulsion without surfactants, exploiting the hydrophilic coil behavior and avoiding costly purification steps. The coil block features address the assembly in the obtained NPs, neat and blended with fullerene derivatives, leading to the nano-aggregation in the active layers. The relationship between the nano-aggregation of the NPs and the device performances will be discussed. [Adv Sustain Sys DOI:10.1002/adsu.201700155]