A new multi-institutional study has found that twisting polymer chains in a controlled manner can significantly change how well they conduct electricity once they are doped. The discovery, led by University of Illinois Urbana-Champaign researchers Ying Diao and Joaquín Rodríguez López, provides fresh insight into how synthetic polymers might eventually replace costlier mineral-based semiconductors in certain types of electronic devices.
Xu, Z., Saiev, S., Qian, P., Nabei, Y., Wang, Z., Rinehart, J. M., Österholm, A. M., Jones, A. L., Lee, J.-H., Hwang, C., Wang, S., Sun, R., Shin, D., Jeon, S., Elangovan, K. E., Vura-Weis, J., Coropceanu, V., Rodríguez-López, J., Reynolds, J. R., … Diao, Y. (2025). Supramolecular chirality largely modulates chemical doping of conjugated polymers. Nature Communications, 16(1), 8381. https://doi.org/10.1038/s41467-025-62915-3
The work, brings together contributions from several research teams. Alongside the Illinois group, collaborators included theorist Jean-Luc Brédas at the University of Arizona, polymer chemist John Reynolds at Georgia Tech, and spectroscopist Dali Sun at North Carolina State University. Their combined efforts centered on understanding how chirality — a persistent twist in a molecule’s backbone — interacts with chemical doping, which is traditionally used to increase conductivity in semiconductor materials.
Ying Diao and Joaquín Rodríguez López from University of Illinois Urbana-Champaign stated,
“In our previous research, increased chirality was found to be harmful for charge mobility. This is because such twisting caused charges to become more localized, reducing their ability to move freely through the material, which lowered mobility and overall conductivity.”
Chirality is already recognized as a fundamental feature in biological and chemical systems, but it has not been widely explored as a design parameter for improving polymer conductivity. In earlier work, Diao’s group observed that increasing chirality made charge transport worse. The twist tended to trap charges instead of allowing them to move freely, reducing mobility and lowering overall conductivity. Because of this, chirality was not considered a helpful factor when designing doped polymer systems.
The new experiments challenge that assumption. Working with a class of conjugated polymers processed in different solvents, the researchers were able to induce varying degrees of twist in the chains. They then doped the materials and measured how the changes in structure influenced conductivity. Surprisingly, once the polymer was doped, the more twisted samples showed higher conductivity rather than lower.
This reversal was unexpected and remains unexplained. One proposed explanation is that chirality may influence the spin of electrons in a way that enhances the doping reaction, but the team emphasized that this idea is still a hypothesis. The exact mechanism behind the improved conductivity is not yet clear, and several competing explanations remain possible.
The study also highlighted how the solvent used during processing affects the way polymers assemble in solution and, ultimately, how much chirality appears in the final film. These assembly pathways appear to influence not only the polymer’s structure but also how effectively the doping reaction takes place. Understanding this solvent-dependent behavior may provide new levers for tuning polymer semiconductors in the future.
Although the findings open an intriguing direction for polymer design, the researchers caution that more work is required before the phenomenon can be translated into commercial technologies. Future experiments will focus on isolating the mechanism, determining whether the effect is general across different polymer families, and assessing how stable the conductivity improvements are under realistic operating conditions.
If these questions can be answered, chiral polymer systems may offer a path toward semiconductor materials that are more sustainable, easier to manufacture and adaptable for emerging device architectures. For now, the results point to a property that has long existed in polymer structures but whose role in doping is only beginning to be understood.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
