New nanoscale research reveals how molecular stiffness could cap the performance of flexible wearable tech.
Researchers at University of Cambridge have taken a first experimental step toward understanding how the molecular mechanics of flexible semiconductors might constrain the performance of future wearable electronics suggesting there could be inherent limits to how fast and efficient bendable devices can be.
At the heart of the investigation is a long-standing but poorly quantified question in flexible electronics: what does “flexibility” actually mean at the atomic level, and does it compromise electrical performance? Traditional rigid silicon electronics are fast in part because their crystal structures provide orderly, stiff pathways for charges to move. Organic semiconductors, the building blocks of rollable screens, soft sensors, and wearable gadgets are instead composed of carbon-based molecules that form softer, bendable solids.
A research team led by scientists at the University of Cambridge used ultra-sensitive atomic force microscopy (AFM) to measure mechanical stiffness down to just a few molecules across thin films of organic semiconductors. Their findings, published in Nature Communications, offer the first direct evidence that the intrinsic stiffness of individual molecules contributes to the total mechanical response of flexible electronic materials.
In the study, the researchers focused on versions of an organic semiconductor known as DNTT, widely used in flexible transistors, altering the length of “side chains” attached to the molecule’s core. Longer, more flexible side chains spaced molecules further apart, producing softer materials when probed with the AFM tip. Shorter side chains yielded stiffer films. This molecular influence on stiffness was confirmed by computer simulations, which matched the experimental observations.
The implications reach beyond mechanical curiosity. If molecular softness affects charge transport and thus electrical speed and efficiency there may be a trade-off between mechanical flexibility and electronic performance in wearable devices. Right now, that link remains unproven, but the tools developed in this work give researchers a way to quantify and design around it.
Looking ahead, insights from this nanoscale stiffness mapping could guide the design of flexible electronic materials that balance bendability with performance, possibly identifying thresholds where softness begins to slow devices. Such knowledge is vital for next-generation wearables that must be both mechanically resilient and electrically fast.
