A research team from the University of Chicago and Argonne National Laboratory has developed a new type of ultrathin transistor, constructed with a layer of atomically thin semiconductor topped by a molecular crystal sheet. Unlike traditional transistors that use larger three-dimensional layers of semiconductors, this device measures only four atoms in thickness.
The new transistor operates on the principle of charge localization—a phenomenon previously observed only in materials cooled to extremely low temperatures—but this device functions at room temperature. The researchers reported that its performance is comparable to high-quality conventional silicon transistors.
“This transistor behaves very differently from a conventional transistor, and it gives rise to a lot of interesting properties that conventional transistors do not have,” said Mengyu Gao, postdoctoral fellow at the University of Chicago and first author on the study published October 23 in Science.
The scientists hope these findings could lead to advances in microelectronics and computing, as well as further basic scientific discoveries. The material used consists of an atom-thick layer of perylene diimide molecules placed atop a three-atom-thick semiconductor layer. During testing, the team found that while the hybrid bilayer conducted electricity efficiently under increasing electron concentrations, it abruptly became an insulator at a certain threshold—an effect not explained by standard transistor theory.
“Right away I saw this dip and knew that we had something interesting,” Gao said. “But when we tried digging down to explain what we saw, we started to realize this was something no one had seen before.”
Professor Jiwoong Park’s laboratory specializes in ultra-thin layered materials and contributed techniques for creating highly pure single-atom crystalline films. When used as transistors, these new materials performed nearly as well as today’s top silicon devices.
Explaining the mechanism, Park stated: “What was striking was that once any electrons can go to the molecule layer, they all will.”
The design eliminates the need for combining different types of semiconductor layers (n-type and p-type), which are essential in standard silicon transistors. It also requires less voltage overall—a benefit for reducing power consumption and addressing heat management challenges prevalent in electronics development.
Another key advantage is that all these effects occur at room temperature. According to Gao: “We have seen other systems that exhibit this charge localization phenomenon, but they all must be cooled down cryogenically to observe this effect.” This makes studying charge localization more practical and accessible.
The research team plans further studies into tuning material properties for potential applications such as creating electron crystals—structures previously achieved only under specific conditions.
“What you see from this is that molecules can be used to design remarkable new electronic materials,” said Park. “We think this could really open new horizons.”
Additional co-authors include graduate students Hanyu Hong, Sicheng Fan, Zehra Naqvi, Ce Liang, Yu Han, Jingyuan Ge; postdoctoral fellows Tomojit Chowdhury, Yuqing Qiu, Dong Hyup Kim; Nathan Guisinger from Argonne; UChicago professors Suriyanarayanan Vaikuntanathan and Chong Liu.
Funding sources for the study include the U.S. Air Force Office of Scientific Research, National Science Foundation, U.S. Department of Energy, Office of Naval Research. Research resources were provided by UChicago MRSEC, Pritzker Nanofabrication Facility and DOE Center for Nanoscale Materials. Park also serves as co-principal investigator for Purdue University's Quantum Probes for Information, Discovery and Control (QuPIDC) Energy Frontier Research Center—which partially supported this work—and aims to develop quantum-enabled probes for information technologies.
Efforts are underway with UChicago Polsky Center for Entrepreneurship and Innovation to explore commercial opportunities stemming from this research.