The consortium includes Kindai University, Ibaraki University, Osaka Metropolitan University, National Yang Ming Chiao Tung University, and National Central University. Its central objective is to establish foundational technologies for semiconductor light-emitting devices that generate circularly polarized luminescence directly from electrical energy. Unlike conventional displays, which typically emit unpolarized light and require additional optical components to manipulate polarization, CP-OLEDs are designed to produce light whose electric field rotates in a defined direction as the wave travels. This additional property could allow light to carry information through intensity, color, and rotational direction simultaneously, opening possibilities in displays, optical communications, three-dimensional imaging, sensing, information security, and emerging spin-based technologies.

Circularly polarized light exists in two forms, commonly described as left- or right-handed, depending on the direction in which the electric field vector rotates. The degree of circular polarization is often evaluated using the dissymmetry factor, a parameter that compares the intensity of left- and right-circularly polarized emission. In practical devices, however, achieving a high dissymmetry factor is only part of the problem. A material may emit strongly polarized light but perform poorly as a light source, while another may offer excellent luminous efficiency but almost no polarization. The Japan–Taiwan project will therefore focus on the difficult balance between polarization density, electrical efficiency, brightness, operating stability, wavelength range, and manufacturability.

The researchers plan to move beyond the standard strategy of embedding chiral light-emitting molecules in an organic electroluminescent device. Chiral molecules possess structures that cannot be perfectly superimposed on their mirror images, and this asymmetry can influence how they interact with light. Although such molecules have enabled important advances in circularly polarized luminescence, they can impose limitations on material selection, device architecture, emission wavelength, and large-scale fabrication. The new collaboration will investigate whether magnetic fields, electric fields, electron spins, and hierarchical material structures can create or control optical asymmetry during the emission process, potentially enabling CP-OLED designs that are less dependent on conventional molecular chirality.

One major research direction is magnetic-field-induced circularly polarized luminescence, or MCPL. When luminescent molecules or electronic states interact with an external magnetic field, their energy levels and spin-related populations can be altered. These changes may affect the balance between left- and right-handed emission, allowing the polarization state of the light to be controlled externally. The Japanese team will contribute expertise in measuring circularly polarized luminescence and evaluating photoluminescence under magnetic fields. Such measurements can reveal how excited states, magnetic interactions, and molecular environments influence the final polarization of emitted light, providing design rules for materials and devices.

The project will also examine electric-field-induced circularly polarized luminescence, known as ECPL. Electric fields can modify charge distribution, energy-level alignment, carrier transport, and the recombination processes that produce light in an organic semiconductor. In an OLED, electrons and holes are injected from opposite electrodes and meet within an emissive layer, where they form excited states before releasing energy as photons. By controlling these processes with electric fields, researchers hope to influence the spin and symmetry of the excited states and produce circularly polarized emission on demand. This approach could provide a route toward electrically tunable polarization, an important capability for compact optical systems and information technologies.

A further component involves the chiral-induced spin selectivity effect, or CISS, in which electrons moving through chiral molecular structures can experience spin-dependent transport. In principle, a chiral pathway may favor the transmission of one electron-spin orientation over the other, linking molecular structure to spin-polarized electronic behavior. The consortium will investigate whether CISS can be integrated with organic semiconductor materials and device structures to control the spin populations involved in light emission. Combining CISS with magnetic and electric field effects could allow the team to manipulate the relationships among charge, spin, and light without relying exclusively on chiral emitters. The research will span visible and near-infrared wavelengths, broadening its potential relevance to both displays and optical sensing.

The Japanese and Taiwanese teams bring complementary capabilities to this challenge. Researchers in Japan specialize in circularly polarized light spectroscopy, magnetic-field-dependent photoluminescence, organic electroluminescent device fabrication, and electrical and optical evaluation. Their Taiwanese partners contribute expertise in circularly polarized luminescent materials, polymers, semiconductor materials, molecular self-assembly, structural characterization, simulation, and semiconductor manufacturing. By combining these areas, the project aims to connect microscopic electronic and spin behavior with macroscopic device performance. The researchers will study how molecular and supramolecular structures organize, how carriers move through complex materials, and how external fields alter emission during device operation.

The collaboration will officially begin with the 2026 Taiwan–Japan Joint Symposium on Next-Generation Circularly Polarized Luminescence Technology, scheduled for September 1 and 2, 2026, in Taiwan. The first day will be held at the Bo-Ai Campus of National Yang Ming Chiao Tung University in Hsinchu, followed by a second day at National Central University in Taoyuan. Thirteen faculty members and students from the five participating universities are expected to attend, along with auditors from Taiwanese universities. The two-day program will include scientific presentations, dedicated sessions for early-career researchers, laboratory tours, and planning meetings intended to coordinate the three-year research program. Graduate students and young scientists will be central participants, reflecting the consortium’s goal of building a lasting scientific network rather than a short-term exchange.

During the project’s planned period from fiscal year 2026 through fiscal year 2028, the researchers hope to establish quantitative design benchmarks for future circularly polarized light-emitting materials and devices. These benchmarks will need to define how polarization strength can be improved while maintaining high luminous efficiency, stable operation, and compatibility with practical fabrication processes. The team also expects to investigate interactions among magnetic fields, electric fields, light, and electron spins, an area that could connect organic electronics with spintronics and quantum-enabled communication. Although the consortium is still at the research and development stage, its approach could influence how optical information is generated, transmitted, secured, and detected. If successful, the work may help transform circular polarization from an additional optical feature into an active control parameter for next-generation optoelectronic devices.

Subject of Research: Development of next-generation circularly polarized organic light-emitting diodes and semiconductor optoelectronic technologies.

Article Title: Japan–Taiwan Consortium Targets Field-Controlled Circularly Polarized OLEDs

Web References: https://mediasvc.eurekalert.org/Api/v1/Multimedia/c9bc560e-f2df-4630-94f8-e000d4a5ef53/Rendition/low-res/Content/Public

Image Credits: Kindai University

Keywords

Circularly polarized light, CP-OLEDs, organic light-emitting diodes, circularly polarized luminescence, magnetic-field-induced luminescence, electric-field-induced luminescence, chiral-induced spin selectivity, organic semiconductors, spintronics, Japan–Taiwan research collaboration

The materials studied by the team exist in two structural forms known as enantiomers. Like a left hand and a right hand, the R and S forms contain the same chemical components but are arranged as mirror images that cannot be perfectly superimposed. Under ordinary, unpolarized light, the two materials can appear nearly identical. Circularly polarized light, however, has an electric field that rotates either clockwise or counterclockwise as the light travels. That twist gives the material an opportunity to distinguish between the two directions, revealing its underlying chiral structure.

The researchers, led by Dr. Joanna Dehnel and Dr. Igal Levine, wanted to determine whether this structural handedness could influence not only how much light the material absorbs, but also what happens to the electrons generated after absorption. In conventional experiments, scientists typically attach metal electrodes to a sample so they can measure electrical currents or voltages. Yet contacts can introduce defects, alter charge movement or create signals that are difficult to separate from the material’s intrinsic behavior. The device itself may therefore become part of the experiment.

To avoid that problem, the team introduced circularly polarized time-resolved surface photovoltage, or CP-TRSPV. The approach uses pulses of circularly polarized light to create electron–hole pairs in the material and then monitors the resulting surface photovoltage without requiring a top electrical contact. A surface photovoltage develops when photoexcited charges separate, producing an imbalance of electrical potential near the surface. By recording how that signal changes over time, researchers can follow charge separation and recombination from nanoseconds through milliseconds.

This broad time window is crucial because the processes involved occur on very different scales. The initial interaction between light and the electronic structure takes place extremely rapidly. Electrons and holes can be created and separated almost immediately, while trapping, release and recombination processes continue for much longer. CP-TRSPV allows these stages to be distinguished without the complications introduced by a fabricated device, offering what the researchers describe as a direct way to listen to the material’s electrical response before it is wired into a circuit.

When the team illuminated the R and S forms with opposite helicities of circularly polarized light, the mirror-image samples responded in opposite ways. The R-form produced a stronger response under right-circularly polarized light, whereas the S-form responded more strongly under left-circularly polarized light. A racemic sample, containing a mixture of the two mirror-image forms and therefore lacking an overall chiral preference, showed no significant difference between the two light helicities. This control result strongly connected the effect to the handedness of the crystal rather than to an accidental difference in sample composition or measurement conditions.

The most striking observation was the scale of the electrical asymmetry. The researchers measured a photovoltage anisotropy factor, known as gSPV, reaching approximately −0.7 for the R material and 0.17 for the S material. The photovoltage difference was roughly 1,000 times larger than the corresponding difference in optical absorption. In other words, the mirror-image materials were not merely absorbing slightly different amounts of light. They were converting that light into separated electrical charges with a far greater handedness-dependent contrast.

The findings are consistent with chiral-induced spin selectivity, or CISS, a phenomenon in which a chiral structure preferentially transmits or separates electrons according to their spin orientation. Spin is a quantum property of electrons that can be thought of, in simplified terms, as an intrinsic form of angular momentum. In a chiral crystal, the combination of molecular arrangement, electronic motion and spin–orbit interactions may favor one spin direction over another as charges move through the material. The result is a structure that behaves somewhat like a microscopic spin filter, potentially separating charges more efficiently when the light’s helicity matches the material’s handedness.

The researchers emphasize that the long-lived photovoltage does not mean that electron spins remain coherent for milliseconds. Instead, the initial spin-selective process occurs rapidly and creates unequal populations of separated charges. Those populations can persist as charges become trapped, released or gradually recombine, leaving behind a measurable electrical signal long after the original spin-dependent event has ended. This distinction is important because it links an ultrafast quantum process to a macroscopic voltage that can be tracked with laboratory instruments.

The new method could change how researchers screen chiral materials. Rather than fabricating a complete device for every new chemical composition, scientists could first use CP-TRSPV to test whether a material produces a strong helicity-dependent response, how quickly charges separate and how long the resulting signal survives. Chiral two-dimensional perovskites are especially attractive because their layered structures can combine strong light absorption with tunable electronic properties, while their handedness may enable control of charge and spin without an external magnetic field. Possible future applications include detectors for circularly polarized light, spin-based electronics and optoelectronic systems that distinguish between different light helicities. By turning a difficult-to-observe quantum effect into a time-resolved electrical signal, the Hebrew University team has provided a potentially high-throughput route toward discovering materials whose hidden microscopic asymmetries could power future technologies.

Subject of Research: Chiral 2D perovskites and helicity-dependent photovoltage

Article Title: Contactless Detection of Giant Helicity-Dependent Photovoltage in Chiral 2D Perovskites

News Publication Date: 8-Aug-2026

Web References: https://doi.org/10.1002/smll.74908

References: Small, DOI: 10.1002/smll.74908

Keywords

Chiral perovskites, circularly polarized light, surface photovoltage, CP-TRSPV, chiral-induced spin selectivity, CISS, electron spin, spintronics, optoelectronics, nanotechnology, materials science, photovoltage anisotropy

The essence of this novel semiconductor lies in its ability to emit circularly polarized light, a trait that enables the transfer of information regarding the "handedness" of electrons. In contrast to traditional inorganic semiconductors, such as silicon, which exhibit symmetrical properties leading to non-directional electron movement, this innovative semiconductor harnesses the chiral characteristics of molecules. Chiral molecules, which can be thought of as mirror images, are prevalent in nature and play crucial roles in biological processes like DNA synthesis. Yet, leveraging this chirality within electronics has historically posed a challenge.

Through the integration of biophilic design principles into molecular architecture, the researchers succeeded in crafting a chiral semiconductor. This was accomplished by guiding stacks of semiconducting molecules to organize into either right-handed or left-handed spiral configurations. The findings from their research have been published in the prestigious journal Science, showcasing not just a notable academic achievement but also an important milestone for future technology.

One of the most promising applications for these chiral semiconductors is their use in display technology. Current display screens are notorious for wasting energy due to inefficiencies in light filtering processes. The chiral semiconductor introduced by these researchers naturally generates light in an orientation that could significantly mitigate such losses, thereby enhancing screen brightness and energy efficiency. This leap forward has profound implications, particularly as the demand for more sustainable technologies continues to grow.

Professor Sir Richard Friend, who collaborated in leading this innovative research from Cambridge’s Cavendish Laboratory, recounted, “When I began my journey with organic semiconductors, many remained skeptical about their potential. However, it is undeniable that they now form the backbone of display technology.” Highlighting the versatility of molecular materials, he likened the freedom to design unique structures to working with a limitless set of building blocks—a stark contrast to the constraints often imposed by rigid inorganic counterparts.

At the heart of this new semiconductor lies a material called triazatruxene (TAT), which self-assembles into a helical configuration, subsequently allowing electrons to spiral effectively along its structure. When stimulated by blue or ultraviolet light, this arrangement causes TAT to emit bright green light, characterized by strong circular polarization. Achieving such an effect in semiconductors had been a formidable challenge until this recent breakthrough, as articulated by Marco Preuss, co-first author from the Eindhoven University of Technology.

Through innovative adaptations in OLED fabrication techniques, the research team successfully integrated TAT into functional circularly polarized OLEDs (CP-OLEDs). These cutting-edge devices exhibited record levels of efficiency, brightness, and polarization, setting a new benchmark in the field. Co-first author Rituparno Chowdhury remarked, “By reengineering the conventional process for manufacturing OLEDs as we employ in smartphones, we’ve discovered a practical method for trapping a stable chiral structure within a non-crystallizing matrix.”

This research is culminative of a prolonged partnership between Sir Richard Friend’s research group and the team of Professor Bert Meijer from the Eindhoven University of Technology. Meijer commented on the significance of their collaboration by stating, “This breakthrough in developing a chiral semiconductor illustrates our meticulous approach to molecular design. We have successfully linked the chirality of our molecular structure to the electrons’ movement—a feat never previously accomplished on this scale.”

The implications of these chiral semiconductors extend far beyond display technologies. Envisioning a future driven by efficient quantum computing and advanced spintronics, these organic materials represent a crucial step forward in evolving electronic mechanisms. Within the growing $60 billion industry of organic semiconductors, this development signifies a turning point that may enhance not only the way we interact with technologies but also how we harness and process information.

Moreover, the work received substantial support from initiatives including the European Union’s Marie Curie Training Network and the European Research Council. Aided by this backing, the researchers are optimistic about tackling the forthcoming challenges and barriers that lie ahead in this rapidly advancing field.

This remarkable research, encapsulating years of collaboration and dedicated inquiry, has not only contributed to a burgeoning field of study but has also provided the scientific community with fresh insights into organic electronics. As the quest for optimizing performance and sustainability in electronic devices continues, this chiral semiconductor promises to be at the forefront of innovation, rooting its significance deeply in the evolution of future technologies.

In summary, this innovative leap in the domain of organic semiconductors enriches our understanding of electronics, presenting exciting potential for the future. By leveraging the intricate properties of molecular chirality, researchers are setting the stage for advanced applications that could redefine our approach to electronics and information technology, heralding in a new era characterized by efficiency and effectiveness.

Subject of Research: Chiral Semiconductors
Article Title: Circularly polarized electroluminescence from chiral supramolecular semiconductor thin films
News Publication Date: 14-Mar-2025
Web References: DOI Link
References: Science Journal
Image Credits: Samarpita Sen/Rituparno Chowdhury

Keywords

Organic semiconductors, display technology, light emitting diodes, molecular electronics, quantum computing, spintronics, semiconductors.

A recent study helmed by Professor Fahad Mahmood of the University of Illinois has unveiled significant findings regarding magnetically intrinsic topological insulators, particularly focusing on manganese bismuth telluride (MnBi₂Te₄). This research not only sheds light on the band structure and electronic properties of MnBi₂Te₄ but also contests previous assertions regarding its electronic band gap, a contentious issue in the scientific community. The team’s findings mark the first demonstration of how external factors, specifically circularly polarized light, can manipulate the material’s properties in meaningful ways.

Diving deeper into the quantum characteristics of materials, this study elucidates the concept of a hidden gap in the electronic band structure of MnBi₂Te₄ under specific light conditions. While previous studies laid the groundwork, experimental evidence remained elusive, until now. The research clearly illustrates that MnBi₂Te₄ exhibits a gapless condition at equilibrium—an observation consistent with some prior studies—yet intriguingly develops a gap when subjected to different orientations of circularly polarized light.

Through rigorous experimentation, the research team employed angle-resolved photoemission spectroscopy (ARPES) to meticulously examine the band structure of MnBi₂Te₄. This technique detects the electron energies emitted when light shines upon a material’s surface and reveals how these energy levels shift under various external conditions. The intricacies of examining the electronic structure facilitate a comprehensive understanding of a material’s behavior, which is pivotal in describing its physical properties.

A defining characteristic of non-magnetic topological insulators is the adherence to time-reversal symmetry (TRS), a principle asserting that the fundamental laws of physics remain unchanged when time is reversed. For non-magnetic TIs, the electron currents exhibit this symmetry, which grants them their remarkable surface conduction properties. However, in breaking TRS, magnetic topological insulators introduce new quantum phases—one that could potentially yield transformative results for modern technology.

Magnetic topological insulators challenge the conventional understanding of TIs. Unlike their non-magnetic counterparts, the introduction of intrinsic magnetism allows for novel phenomena, such as the quantum anomalous Hall effect (QAHE), which appears when TRS is disrupted. The QAHE facilitates specific energy states that permit currents to flow with minimal resistance—an invaluable property for creating energy-efficient electronic devices. Yet, the inherent challenge is that these magnetic states are typically achieved through external magnetic fields, complicating their practicality for widespread adoption.

Professor Mahmood and his team grappled with the longstanding debate surrounding the existence of a band gap in MnBi₂Te₄. While some experimental research indicated observable gaps, conflicting studies cast doubt on these findings. In their endeavor to clarify this scientific ambiguity, the team utilized Floquet-Bloch manipulation—a state of the art technique that harnesses light to alter material properties and induce new quantum behaviors. By meticulously applying circularly polarized light to MnBi₂Te₄, the researchers successfully induced a band gap, delivering compelling evidence that aligns with theoretical predictions.

The results indicated a striking asymmetry between the responses of the material under right-circularly polarized (RCP) and left-circularly polarized (LCP) light. In the antiferromagnetic low-temperature phase, RCP light opened a gap that was nearly double the size induced by LCP light. This discrepancy in gap sizes robustly signifies the breaking of TRS. The research effectively establishes that altering the direction of light not only influences electron behavior but also has practical implications for the manipulation of quantum states.

Key to these findings is the ability to explore the electronic structure of materials through manipulation techniques such as Floquet-Bloch engineering. By applying these advanced methodologies, scientists now have a tangible way to influence the electronic properties of TIs without relying on cumbersome external fields, leading to more manageable experimental conditions. This breakthrough opens doors to further studies on varied materials and promises an expanded understanding of the mechanisms underlying quantum matter.

As the research progresses, there remains a wealth of uncharted territory awaiting exploration, particularly regarding the broader implications of manipulating magnetic TIs using advanced light techniques. The variations in band gaps identified by the research team not only highlight the interplay between magnetism and electronic states but also raise questions about the underlying mechanisms driving these behaviors.

In the pursuit of deeper insights into MnBi₂Te₄ and similar materials, the potential for real-world applications in electronic devices and quantum computing remains tantalizingly close. By deciphering the complex interactions within these systems, researchers hope to design and develop innovative technologies that could meet the growing demands of modern electronic systems.

The implications of this work extend far beyond the immediate study, as magnetic TIs like MnBi₂Te₄ promise to revolutionize the landscape of condensed matter physics and materials science. Understanding the roles of intrinsic properties like magnetism in determining material behavior sets the stage for potential breakthroughs that could lead to the next generation of electronics, emphasizing the significance of continued exploration in this exciting field.

Lastly, the findings are supported by significant federal grants and institutional support, highlighting the importance of collaborative efforts in driving forward scientific inquiry. As researchers continue to delve into the mysteries of topological insulators, the promise of uncovering further revolutionary discoveries in the physics of condensed matter remains vibrant.

Subject of Research: The hidden gap in the electronic band structure of manganese bismuth telluride (MnBi₂Te₄)
Article Title: Floquet–Bloch manipulation of the Dirac gap in a topological antiferromagnet
News Publication Date: 21-Jan-2025
Web References: https://doi.org/10.1038/s41567-024-02769-6
References: Nature Physics journal
Image Credits: Photo by Heather Coit, Illinois Grainger Engineering

Keywords

1. Topological insulators
2. Quantum anomalous Hall effect
3. Circularly polarized light
4. Manganese bismuth telluride
5. Floquet-Bloch manipulation
6. Electron band structure
7. Time-reversal symmetry