Liao’s work focuses on the development of a new experimental platform that transforms scanning ultrafast electron microscopy from a purely imaging technique into a tool for controlling quantum interactions. By combining the nanoscale spatial resolution of a scanning electron microscope with the picosecond-scale time resolution of an ultrafast laser, Liao and his team have developed one of the few scanning ultrafast electron microscopes (SUEM) in the United States. This technology allows researchers to capture dynamic processes in quantum materials, effectively taking “movies” of energy transport that was previously understood only through theoretical calculations and simulations.

The central goal of Liao’s upcoming project is to study polaritons, which are light-induced excitations that form when photons interact with matter. In this specific context, the matter consists of atomically thin materials, often referred to as two-dimensional materials, whose electrons are free to interact with incoming light. Generally, electrons and photons do not interact directly in a vacuum, despite being among the most common particles encountered in the universe. However, Liao proposes that by strategically introducing quantum materials as an intermediate, it is possible to break this barrier and induce various kinds of interactions between these particles.

“We’re going to look at how electrons talk to photons in a vacuum,” Liao explained. He noted that while these particles are ubiquitous, their direct interaction in a vacuum is typically absent. The introduction of quantum materials serves as a bridge, allowing for the design of systems where electrons and photons can communicate. Liao expressed that he is very excited about this opportunity, describing it as one of the projects he is most proud of. The support from the Moore Foundation will enable him to take the technology to the next level, moving beyond observation to active control of these quantum phenomena.

The research has the potential to study moiré systems, which are configurations of two-dimensional layers of material that can generate new and promising electronic properties. According to the Moore Foundation, Liao’s work will also explore other nonequilibrium phenomena. These studies aim to lay a foundation for advances in nanoscale electron optics, quantum coherent measurement, and electron beam control. By understanding how to manipulate these interactions, researchers may gain deeper insights into the behavior of quantum materials, which are essential for cutting-edge technologies in semiconductor research and quantum computing.

Liao joins twenty other investigators who have been selected for this 2026 cohort. Each investigator will receive $1.35 million over five years to accelerate their research breakthroughs. This funding model is designed to provide the flexibility necessary for scientists to follow ideas when research results lead them down new pathways. Theodore Holdapp, program director for the Experimental Physics Investigators Initiative, stated that the foundation aims to give brilliant mid-career scientists the kind of sustained support that allows them to take on risky experiments. With nearly 100 investigators now at work under this initiative, the foundation is seeing a range of bold and original science that it hoped would be possible.

The significance of Liao’s work lies in its ability to witness, study, and eventually control interactions between atomic and subatomic particles. Although these behaviors are rapid and fleeting, they underlie some of the most advanced technologies in various fields. By directly observing these phenomena, Liao’s team has already made strides in visualizing processes such as photoexcited charges traveling across materials. The new platform will extend these capabilities, allowing for a more comprehensive understanding of how light and matter interact in complex quantum systems. This shift from passive imaging to active control represents a significant leap in experimental quantum and materials sciences.

The use of scanning ultrafast electron microscopy in this context is particularly innovative because it bridges the gap between spatial and temporal resolution. Traditional microscopes may offer high spatial resolution but lack the time resolution to capture fast-moving quantum events, while ultrafast lasers provide time resolution but often lack the spatial precision needed to observe atomic-scale phenomena. Liao’s SUEM overcomes these limitations, enabling the capture of dynamic processes in real time. This capability is crucial for understanding the fundamental mechanisms that govern quantum materials, which are increasingly important in the development of next-generation electronic and photonic devices.

As Liao prepares to begin this new phase of research, the focus will be on designing materials that can properly induce interactions between electrons and photons. The strategic introduction of quantum materials as an intermediate is key to this approach. By carefully engineering these materials, researchers can create conditions where light and matter interact in novel ways. This work not only has fundamental scientific implications but also has the potential to lead to practical applications in quantum computing and other advanced technologies. The Moore Foundation’s support will be instrumental in bringing this vision to fruition, providing the resources needed to develop and test these new experimental platforms.

In summary, Bolin Liao’s selection as a 2026 Experimental Physics Investigator marks a significant milestone in the field of quantum materials science. His work to develop a platform for imaging and controlling quantum interactions with 2D materials represents a bold step forward in our ability to understand and manipulate the fundamental forces that govern the quantum world. With the support of the Gordon and Betty Moore Foundation, Liao is poised to make groundbreaking discoveries that could have far-reaching implications for both basic science and technological innovation. The project highlights the importance of sustained, flexible funding in enabling scientists to pursue high-risk, high-reward research that pushes the boundaries of what is possible in experimental physics.

Subject of Research: Tech & Engineering

Article Title: Mechanical engineer Bolin Liao to develop platform for imaging and controlling quantum interactions with 2D materials

Article References: Mechanical engineer Bolin Liao to develop platform for imaging and controlling quantum interactions with 2D materials. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Quantum Materials, Scanning Ultrafast Electron Microscopy, UC Santa Barbara, Gordon and Betty Moore Foundation, 2D Materials, Polaritons, Experimental Physics, Nanoscale Electron Optics, Mechanical, engineer, Bolin, Liao

The central idea behind the new work is the polariton, a hybrid quasiparticle formed when the excited state of an organic molecule couples strongly enough to a confined optical mode that the two lose their separate identities. In this regime, the energy levels split into upper and lower polariton branches, and emission can be funneled toward the lowest energy state of the system. Because the optical mode imposes its own dispersion and density of states on the hybrid excitation, the emitted spectrum can be dramatically narrowed compared with the broad fluorescence band of the bare molecule. For display applications, where each subpixel must produce a saturated primary color, this spectral compression is enormously valuable, since narrow emitters translate directly into wider color gamuts as defined by standards such as Rec. 2020.

Historically, however, polariton light emitting devices have struggled to convert this spectral elegance into practical performance. Many early demonstrations relied on phosphorescent emitters containing iridium or platinum, materials that are expensive, supply constrained, and increasingly undesirable from a sustainability standpoint. Moreover, the strong coupling cavity structures used to form polaritons often introduce their own problems. The angular dispersion of the cavity mode means that the emission wavelength can shift substantially as the viewer moves off axis, producing the familiar color drift that plagues conventional OLEDs at large viewing angles. And the process of relaxing from high energy states down to the emissive ground state of the polariton landscape can be inefficient, throttling the maximum achievable external quantum efficiency.

The research team behind the new device addressed these challenges by building their polariton OLED around thermally activated delayed fluorescence, or TADF, a mechanism that has emerged over the past decade as a metal free route to harvesting both singlet and triplet excitons in organic emitters. In a TADF molecule, the energy gap between the lowest singlet and triplet states is made small through careful molecular design, so that triplet excitons can be thermally upconverted back to emissive singlet states at room temperature. In principle this allows every electrically generated exciton to contribute to light emission, matching the internal efficiency of phosphorescent systems without any rare metal content. Combining this exciton harvesting machinery with a strong coupling microcavity, the researchers created a device in which delayed fluorescence feeds the polariton modes rather than simply radiating through the usual broad molecular transition.

The resulting emission characteristics are striking. The devices produce spectrally narrow output with linewidths far below those of standard fluorescent and TADF OLEDs, which typically emit over tens of nanometers. The polariton mediated emission concentrates the radiated light into a tight spectral band whose position is set primarily by the cavity design rather than by the full molecular vibronic envelope. Equally important, the emission remains stable as a function of viewing angle. In conventional microcavity OLEDs, the resonance wavelength blue shifts as the observation angle increases because the optical path length through the cavity effectively shortens. The polariton architecture reported in the new study suppresses this angular dependence, so the color a viewer sees remains essentially unchanged across a wide range of angles, a property that is critical for large panel displays viewed by multiple people at once.

Efficiency is the third pillar of the demonstration. The researchers report highly efficient device operation, with external quantum efficiency figures that place the polariton OLED among the best performing narrowband organic emitters, while retaining the metal free character of the TADF emitter. Achieving this required careful balancing of the optical and electrical design. The cavity must be strong enough to reach the regime of genuine strong coupling, where the energy exchange between exciton and photon outpaces all loss processes, yet the device must still inject charge carriers efficiently and allow excitons to form and relax into the polariton states without excessive nonradiative loss. The team optimized the layer stack, the emitter concentration, and the mirror structures to satisfy these competing requirements simultaneously.

The physics underlying the angular stability deserves a closer look. In a planar microcavity, photon modes obey a parabolic dispersion, with energy increasing as the in plane wavevector grows. Excitons, by contrast, are essentially dispersionless because molecules are fixed in place. When the two hybridize, the resulting polariton branches inherit a mixture of both characters. Near the crossing point of the bare exciton and photon energies, the lower polariton branch flattens relative to the pure photon dispersion, reducing the rate at which its energy changes with angle. By engineering the detuning, that is, the energy offset between the exciton resonance and the cavity resonance, the researchers positioned their emission on a portion of the polariton dispersion where this flattening is pronounced, locking the output color in place for off axis viewers.

The narrowband character arises from a complementary mechanism. The density of optical states in the cavity is strongly frequency dependent, and in the strong coupling regime the lowest polariton state acts as an efficient sink into which excitations relax before radiating. Instead of every molecule emitting independently across its inhomogeneously broadened spectrum, the ensemble funnels its energy into a single well defined hybrid mode. This relaxation funnel effect compresses the emission linewidth and can also shorten the effective radiative lifetime, since the polariton carries photonic character that couples efficiently to the outside world. Faster emission is not merely a curiosity; it reduces the time excitons spend in states vulnerable to annihilation processes that degrade efficiency at high brightness, one of the persistent bottlenecks in OLED development.

The choice of TADF as the gain medium is what makes the whole scheme electrically practical. Fluorescent emitters can, in principle, address only the twenty five percent of excitons formed as singlets under electrical excitation, capping their internal efficiency at a low level. Phosphorescent emitters harvest everything but require precious metals. TADF molecules harvest everything using only abundant organic elements, and the delayed fluorescence channel provides a steady supply of singlet excitons that can couple to the cavity mode. The new work demonstrates that this supply can be routed into polariton states efficiently enough to sustain bright, narrowband output, resolving a long standing question about whether metal free emitters could power high performance polariton devices.

The implications extend beyond displays. Narrowband, angle stable organic sources are attractive for optical communications, sensing, and spectroscopy, wherever a compact, tunable, low cost light source with well defined color is needed. The demonstration also energizes the broader field of polaritonic engineering, in which researchers seek to use strong light matter coupling to modify chemical reaction rates, energy transport, and material properties. Showing that a technologically mature emitter class like TADF can be integrated into a strongly coupled device with high efficiency suggests that polariton concepts are moving from laboratory physics toward manufacturable technology. As fabrication techniques for high quality optical cavities mature and molecular design of TADF emitters continues to advance, the combination of saturated color, viewing angle robustness, and metal free efficiency reported here may well define the next generation of organic optoelectronics.

Subject of Research: Polariton organic light emitting diodes employing thermally activated delayed fluorescence for narrowband, angle-stable, high-efficiency emission

Article Title: Narrowband, angle-stable, and highly efficient polariton organic light emitting diodes employing thermally activated delayed fluorescence

Article References: Mischok, A., Lennartz, S., Gruber, V., Tenopala-Carmona, F., Witt, J., Hillebrandt, S., & Gather, M. C. (2026). Narrowband, angle-stable, and highly efficient polariton organic light emitting diodes employing thermally activated delayed fluorescence. Light: Science & Applications, 15(1), Article 378. https://doi.org/10.1038/s41377-026-02415-1

Image Credits: AI Generated

DOI: 10.1038/s41377-026-02415-1

Keywords: organic light emitting diodes, polaritons, thermally activated delayed fluorescence, strong light-matter coupling, narrowband emission, angular color stability, microcavity, external quantum efficiency, display technology, metal-free emitters, exciton harvesting, optoelectronics