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The targeted assembly of a wealth of functional architectures for soft photonics and electronics relies on a rigorous understanding of semiconducting polymer phase behavior. While many useful correlations have been established in the field of commodity plastics, unifying theories for their semiconducting counterparts are, however, more challenging to develop because of the rich phase behavior frequently displayed by these macromolecules, due in part to their complex chemical structures typically based on relatively rigid backbones and elaborate side-chain motifs. Solid-state structure formation and resulting properties are therefore especially sensitive to thermal and temporal parameters during processing, rendering device fabrication a challenging task that too often relies on time-consuming trial-and-error procedures. To understand the thermodynamic and kinetic factors of plastic semiconductor solidification and, for example, thin-film growth relevant for device fabrication, detailed knowledge of the intricacies of macromolecular semiconductors’ phase behavior must be gained and ideally combined with temperature/composition, temperature/confinement, and/or time/temperature/transformation- phase diagrams. This will open pathways toward a knowledge and methodology platform for the controlled materials assembly of soft electronics/photonics systems very much in analogy to the approaches used in metallurgy and the inorganic electronic materials field. In turn, a step change in how we design and process soft electronic products might be achieved, with impact on the broader soft matter area.

The vivid iridescent response from particular butterflies is as an excellent example of how micro-engineered hierarchical architectures that combine physical structures and pigmentary inclusions create unique colouration. To date, however, detailed knowledge is missing to replicate such sophisticated structures in a robust, reliable manner. Here, we deliver spheres-in-grating assemblies with colouration effects as found in nature, exploiting embossed polymer gratings and self-assembled light-absorbing micro-spheres.

All-conjugated block copolymers, which can self-assemble into well-ordered morphologies, provide exciting opportunities to rationally design and control the nanoscale organization of electron–donor and electron–acceptor moieties in optoelectronic active layers. Here we report on the steady-state and time-resolved optical characterization of block copolymer films and solutions containing poly(3-hexylthiophene) as the donor block and poly(9,9-dioctylfluorene) with and without copolymerization with benzothiadiazole as the acceptor block. Transient absorption measurements suggest rapid charge transfer occurs in both systems, with higher efficiency observed in the latter composition. These results indicate that this class of materials has promise in preparing highly ordered bulk heterojunction all-polymer organic photovoltaic devices.

We show here that treatment of thin films of conjugated polymers by illumination with light leads to an increase of the intensity of their photoluminescence by up to 42%. The corresponding enhancement of absorbance was much less pronounced. We explain this significant enhancement of photoluminescence by a planarization of the conjugated polymer chains induced by photoexcitations even below the glass transition temperature, possibly due to an increased conjugation length. Interestingly, the photoluminescence remains at the enhanced level for more than 71 h after treatment of the films by illumination with light, likely due to the fact that below the glass transition temperature no restoring force could return the conjugated chains into their initial conformational state.

Due to the rather low efficiencies of conjugated polymers in solid films, their successful applications are scarce. However, recently several experiments indicated that a proper control of molecular conformations and stresses acting on the polymers may provide constructive ways to boost efficiency. Here, we report an amazingly large enhancement of photoluminescence as a consequence of strong shear forces acting on the polymer chains during nanofilm dewetting. Such sheared chains exhibited an emission probability many times higher than the nonsheared chains within a nondewetted film. This increase in emission probability was accompanied by the emergence of an additional blue-shifted emission peak, suggesting reductions in conjugation length induced by the dewetting-driven mass redistribution. Intriguingly, exciton quenching on narrow-band-gap substrates was also reduced, indicating suppression of vibronic interactions of excitons. Dewetting and related shearing processes resulting in enhanced photoluminescence efficiency are compatible with existing fabrication methods of polymer-based diodes and solar cells.