Marangoni-Coupled Alignment in a Semiconductor-Elastomer Blend for Stretchable Electronics

Semiconducting polymer-elastomer blends are a promising material class for flexible and stretchable electronics due to their superior mechanical performance and ability to maintain charge transport at large strains. The semiconducting polymer phase segregates into nanofibrils upon spin- or blade-coating and under certain conditions these fibrils can be aligned for anisotropic charge transport. Here, we report on a long-wavelength Marangoni instability in the coating process that leads to significant variation in the local semiconducting polymer fibril alignment. AFM, resonant soft x-ray scattering (RSoXS) and near-edge x-ray absorption fine structure (NEXAFS) quantify the morphology and these measurements are correlated to thin-film transistor data to characterize the impact on charge transport. Quantifying and potentially controlling coating instabilities is important for device optimization, especially in the scale-up process.