In Situ Study of Molecular Aggregation in Conjugated Polymer/Elastomer Blends toward Stretchable Electronics

Abstract

Conjugated polymers exhibit potential for the development of next-generation stretchable electronics. However, an understanding of molecular aggregation during solution processing and its influence on thin-film morphology is still underexplored. Here, the influences of molecular aggregation on the film morphology, phase purity and phase separation, and mechanical and electrical properties of a partially compatible blend of conjugated polymer poly(indacenodithiophene-co-benzothiadiazole) (IDTBT) and elastomer polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) were systematically examined. When using high-boiling-point (b.p.) solvents, namely, toluene and chlorobenzene, large-scale liquid−liquid phase separation predominates IDTBT aggregation in blend films, leading to isolated IDTBT domains and, thus, poor electrical performance. In contrast, fast solvent evaporation from low-b.p. chloroform suppresses large-scale phase separation and enhances IDTBT aggregation via nanoconfinement effect. The nanoconfinement effect enables us to achieve a stretchable film with a low elastic modulus of 72 MPa, a respectable crack-onset strain of 326% (ca. 3−14 times larger than the neat IDTBT films), and a negligible loss of mobility (ca. 0.7 cm 2 V −1 s −1 ) at 100% strain. These results provide insight into molecular aggregation and thin-film morphology in conjugated polymer/elastomer blends for high-performance stretchable electronics.

Controlling Solution‐State Aggregation and Solid‐State Microstructures of Conjugated Polymers by Tuning Backbone Conformation

“…[14][15][16][17][18][19][20][21][22] Factors affecting solution-state aggregation have been extensively investigated, and various methods aimed at fine-tuning solution-state aggregation have been developed, such as controlling the solution temperature and solvent used for device fabrication, etc. [23][24][25][26][27][28][29] Moreover, the effect of intrinsic properties of conjugated polymers, e.g., regioregularity, on solution-state aggregation was also explored. [30] The backbone conformation, interunit torsion angles in particular, is also of great importance in improving the performances of conjugated polymers.…”

Increasing H-Aggregates via Sequential Aggregation to Enhance the Hole Mobility of Printed Conjugated Polymer Films

“…The absorption spectrum of PDPP-TVT in pure CF exhibited a noticeable change in the first 3 s, before becoming almost constant. On the other hand, the absorption spectrum of PDPP-TVT in CF with 5% BrN exhibited a smooth evolution then changed between 1000 and 2000 s. These results demonstrate that a small amount of BrN can significantly prolong the film formation dynamics of PDPP-TVT . The absorption spectra of the resulting thin films are shown in Figure b.…”

From stretchable and healable to self-healing semiconducting polymers: design and their TFT devices

“…10b). 136 When solvent with high-b.p. was utilized as the processing solvent (Tol and CB), there was a phase separation of IDTBT:SEBS blend that resulted in large isolated IDTBT domains, deterring the charge transport efficiency and mechanical deformation of the films.…”

“…10b). 136 When a solvent with high-bp was utilized as the processing solvent (Tol and CB), phase separation of the IDTBT:SEBS blend occurred, which resulted in large isolated IDTBT domains, deterring the charge transport efficiency and mechanical deformation of the films. In contrast, the utilization of low-bp such as CF could effectively prevent the large-scale phase separation and promote the formation of a fiber network through the nanoconfinement effect in blend films.…”

“…(b) Molecular structures of the conjugated polymer IDTBT, elastomer SEBS, and the effect of different deposition treatments on the electrical and mechanical properties of IDTBT and IDTBT:SEBS blend. 136 Copyright: 2022, the American Chemical Society. (c) Representative structural morphologies of SP:IP blend and the DFT-optimized molecular models.…”