03 Sep Energy transport in ultrathin materials
Understanding how energy is transported in ultrathin materials is an important step towards developing new photonic devices. Researchers at Kiel University (CAU) have now observed a previously unknown transport mechanism in a hybrid structure consisting of a perovskite and hexagonal boron nitride (hBN). Atomic defects play a crucial role in this process.
Atomic defects as transport pathways
In the system investigated, the perovskite initially absorbs energy, which is stored in excited states known as excitons. According to the researchers’ findings, the energy is transferred from these states to atomic defects in the boron nitride. The defects can absorb the energy and pass it on through a network.
The team was able to detect a signal up to 150 µm from the original excitation site. The measured energy transport length was approximately 142 µm. According to the researchers, these distances cannot be explained by exciton motion alone or by optical waveguiding. Instead, they attribute the observed transport primarily to interactions between the defects and to the repeated absorption and emission of light within the defect network.
Optical fiber tracks the light signal
For their investigations, the team used a cathodoluminescence measurement technique developed at Kiel University. The researchers locally excited the material with an electron beam and collected the resulting light using an optical fiber. While the excitation site remained fixed, the fiber was moved progressively farther away. This allowed the team to demonstrate that the light signal remained detectable even at a considerable distance from the excitation site.
Professor Nahid Talebi leads the Kiel research team that investigated the new energy transport mechanism. Image: Julia Siekmann / Kiel University
Potential for quantum photonics
Of particular interest for potential applications is the fact that the effect occurs at room temperature. The team sees potential for devices in which energy or information is transported via optical excitations. Possible applications identified by the researchers include quantum transducers for transferring quantum information between different systems and optoelectronic interconnects for high-speed data transmission.
In further studies, the researchers aim to determine how the energy exchange within the material can be controlled. The findings could provide a basis for the further development of hybrid quantum materials and photonic devices based on them.
Original publication:
[S. Darbari, P. Bittorf et al.: Exciton Energy Routing via Defect Networks in hBN/2D Perovskite Hybrids; ACS Nano 20 (31), 2026, 21739–21751; DOI: 10.1021/acsnano.6c03445]
Source: www.uni-kiel.de
Image: Nahid Talebi / Kiel University
Caption: Illustration of the measurement method: An electron beam excites the material while an optical fiber collects the emitted light at different positions.