Physicists at the Cavendish Laboratory have unveiled innovative methods to enhance the performance of organic semiconductors, potentially revolutionising electronic devices and energy conversion technologies
Dr. Dionisius Tjhe, a Postdoctoral Research Associate leading the study, along with his colleagues, has identified new techniques to significantly increase the conductivity of doped polymer semiconductors.
Their findings, published in Nature Materials, show the ability to extract electrons from organic semiconductors at outstanding levels.
Sustainable energy solutions
Traditionally, only a fraction of electrons in the valence band could be removed, but in their experiments, Tjhe and his team managed to empty the valence band in certain polymers. They managed to remove electrons from even deeper energy levels, a first in semiconductor research.
Thermoelectric devices convert waste heat into electricity, and improving their efficiency could pave the way for more sustainable energy solutions.
Understanding polymers
The key to these advancements lies in understanding the unique properties of organic polymers. Unlike traditional semiconductors such as silicon, which are less conducive to emptying the valence band due to their crystalline structure, polymers offer a more disordered arrangement that facilitates these groundbreaking effects.
The researchers discovered another method to boost thermoelectric performance using a field-effect gate. This technique allows precise control over the number of charge carriers (holes) in the semiconductor without affecting the number of ions, overcoming a common limitation in previous approaches.
One of the most intriguing findings of the study involves exploiting a non-equilibrium state known as the Coulomb gap. This phenomenon, typically observed in disordered semiconductors at low temperatures, unexpectedly enhances both thermoelectric power output and conductivity simultaneously—a rare feat in semiconductor physics.
“Coulomb gaps are notoriously hard to observe in electrical measurements because they only become visible when the material is unable to find its most stable configuration,” remarks Dr. Ian Jacobs, Royal Society University Research Fellow at Cavendish Laboratory.
Despite these developments, the researchers acknowledge that further work is needed to scale these improvements across bulk materials rather than just surface layers. Their research sets a clear trajectory for future investigations into enhancing organic semiconductor performance.
With potential applications ranging from energy harvesting to electronic devices, the implications of this research are far-reaching. As Dr. Tjhe concludes, “Transport in these non-equilibrium states has once again proved to be a promising route for better organic thermoelectric devices”
