Japanese Scientists Discover “Dark Excitons” in Electronic Devices

Published on 10/23/2025 Last updated: 16:27 (Mecca Time)

Using advanced spectroscopic analysis technology, a team of physicists at the Okinawa Institute of Science and Technology in Japan has achieved a groundbreaking accomplishment. They were able to track the mysterious “dark excitons” within thin atomic materials, according to a study published in the journal “Nature Communications.”

The discovery of the path of these quantum particles is expected to contribute to a qualitative shift in information technology and enhance our understanding of quantum computing, data storage, and energy-efficient electronics. It also paves the way for new innovations and developments in classical and quantum information technologies.

In addition, this discovery opens up broader prospects for studying and analyzing semiconductors at the atomic level, which may contribute in the future to improving the capabilities of these materials, which are a fundamental element in modern technical industries.

Strange Particles

Excitons are quasiparticles made up of electron-hole pairs. These particles exist in extremely thin semiconductors and are electrically neutral, causing them to behave differently from other particles such as negatively charged electrons.

: Dr. David Bacon, a researcher at the Okinawa Institute of Science and Technology and one of the lead authors of the study, explains: “Excitons are electron-hole particles, bound together by Coulomb forces.”

He adds: “Excitons are a class of materials that are used in many modern technological devices, including optoelectronic devices, such as photovoltaic cells, solar cells, and light-emitting devices such as LEDs, as well as lasers and smartphones.”

Dr. Bacon points out that “excitons are generally formed from the electronic transition process that takes place in semiconductors, when semiconductors absorb photons of light, which causes negatively charged electrons to move from a lower energy level to a higher level. This transition leaves behind positively charged vacant spaces called holes in the low energy level, where electrons and holes with opposite charges attract each other and begin to rotate around each other, which results in the formation of excitons.”

Dark and Bright Excitons

Dr. Bacon explains that excitons are classified according to the rotation of their electrons into two types: bright excitons and dark excitons.

He explains that “bright excitons consist of electrons and holes that have the same rotation, which takes a spin form, and are formed when the material is optically excited. Because they interact with light, they appear in all forms of optical spectroscopy.”

As for dark excitons, they do not interact with light directly, and therefore cannot be easily seen in ordinary optical experiments.

Bacon adds that “the results of our recent study show that after the formation of bright excitons, a series of dark excitons are formed, the arrangement and rate of formation of which depends on the temperature of the sample, in addition to the power of the excitation pump.”

: Professor Keshav Dani, the lead author of the study, emphasizes the importance of this achievement, saying: “Dark excitons have enormous potential as carriers of information because they are inherently less susceptible to interaction with light, and therefore less susceptible to degradation of their quantum properties.”

He adds: “This disappearance makes studying and manipulating them very difficult, but we have already paved the way for creating, monitoring, and manipulating dark excitons, in a previous achievement at the Okinawa Institute of Science and Technology in 2020.”

Accessing Dark Excitons

Using the advanced “Time- and Angle-Resolved Photoemission Spectroscopy” system at the Okinawa Institute of Advanced Technology, the team was able to track the properties of all excitons after creating bright excitons in semiconductors. Over time, the amount of momentum, spin state, and electron and hole levels were determined simultaneously.

: Xing Zhu, the first co-author and doctoral student in the unit, explains: “In the field of electronics in general, the charge of the electron is manipulated to process information.”

He adds: “In the field of spin electronics, we exploit the rotation of electrons to transmit information. In another type of electronics in dark excitons, known as valleytronics, the crystal structure of unique materials enables us to encode information in distinct momentum states of electrons.”

Zhu explains that the ability to use valley electrons for dark excitons to transmit information makes them a promising candidate for quantum technologies.

The discovery of the path of these quantum particles is expected to revolutionize information technology and our understanding of quantum computing, data storage, and energy-efficient electronics.

It also paves the way for new innovations and developments in classical and quantum information technologies, in addition to opening the door to studying semiconductors more broadly, and seeing them at the atomic level in a better way, which will contribute in the future to improving the capabilities of this class of materials, which are one of the main components in modern technical industries.