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On Friday, March 20, Sarah Kromer defended her PhD Dissertation titled Tuning Metal Interactions Through Ligand Modification in Platinum(II) Dimers. Sarah is one of the very few ultrafast laser experts in Phil Castellano group, and she contributed immensely to multiple cutting edge collaborations with leading research centers, both nationwide and internationally. Congratulations, Sarah! We hope to see you around for a while.

Is putting carbon-free laser-driven fusion energy on the grid by the 2030s possible? In August 2022, when the team of scientists at Lawrence Livermore National Lab’s (LLNL) National Ignition Facility (NIF) fired a shot that achieved a yield of 1.35 megajoules (MJ) of fusion energy with 1.9 MJ of laser energy, it was a long-awaited scientific breakthrough signaling fusion burn.

Later that same year during another inertial fusion (a.k.a. laser-driven fusion) experiment, scientists achieved a yield of 3.15 MJ of fusion energy with 2.05 MJ of laser energy and attained ignition. It was a thermonuclear fusion reaction created within the lab—and it kicked off a global race to put carbon-free laser-driven fusion energy on the grid by the 2030s or 2040s.

“This was a turning point when NIF first successfully showed that inertial fusion was possible, and the key is having the right kind of fuel—deuterium-tritium—and using lasers to compress and fuse it to generate gain (more energy out than put in),” says Arianna Gleason, staff scientist and deputy director of SLAC’s High Energy Density Science division. “It’s like sustaining the fuel of a star—just for a fraction of a second within a laboratory.”

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Traditional lenses made of germanium tend to cost hundreds or thousands of dollars and can’t be repaired when damaged—but a lower-cost sulfur polymer lens option is about to become a gamechanger for infrared (IR) thermal imaging cameras because it can be mass produced, repaired, and recycled. Thermal imaging is currently used for applications like defense, security cameras, driver-assist functions, fire detection and firefighting, smart appliances, and many others. As the costs of detectors comes down, the optics (lenses) often remain a cost-limiting component. It tends to be a bottleneck for emerging consumer products that require low-cost thermal imaging cameras.

“Traditional lenses for thermal imaging cameras are made from expensive materials such as germanium, high-grade silicon, and chalcogenide glass,” says Chalker. “These materials are very high performing, but their high prices, low-throughput manufacturing, and poor recyclability are limitations. In the case of germanium, global supplies are highly restricted because of its strategic use for defense. Lower-cost alternatives are required—especially for civilian applications.”

Polymers for thermal imaging lenses

Chalker’s lab was inspired by the creative work of Professor Jeff Pyun’s lab at the University of Arizona. “They previously demonstrated that sulfur-rich polymers made from ultralow-cost elemental sulfur have properties well suited to thermal imaging applications,” he explains. “Our team at Flinders developed several ways to make such polymers during the past decade, so we thought we could contribute to the thermal imaging applications of these materials. The specific polymer we made had been predicted to be useful for thermal imaging—on theoretical grounds—but no synthesis had been achieved due to complex chemistry and side reactions in previous approaches. Our lab loves a synthetic chemistry challenge, so we set out to solve the problem.”

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The Castellano Group extends its utmost congratulations to Adrienne Faulkner on successfully passing her preliminary defense. Adrienne presented her computational work on heteroleptic Cu(I) species, investigating how different ligand motifs and electronic structures influence the excited-state lifetimes of copper complexes. Her findings contribute to a deeper understanding of structure–property relationships in Cu(I) photosensitizers and helps inform the rational design of more efficient, earth-abundant photochemical systems.

In addition to academic achievements, Adrienne’s unwavering support and generosity toward others have made her an invaluable part of the group. The Castellano team is very proud of Adrienne’s accomplishments and looks forward to the next stage of her graduate career.

An investigation of Pt(II) dimer systems that undergo metal-metal-to-ligand charge-transfer, featuring work from Sarah Kromer and Nicolas Durand in a collaboration with Lin Chen group at the Argonne National Labs! titled “Spin-Vibronic Effect in Photoinduced Electron Transfer” was published in the Journal of Physical Chemistry Letters.
Check it out here: https://pubs.acs.org/doi/10.1021/acs.jpclett.5c02396

“Programmable Light-Driven Color Tuning of Perovskite Quantum Dots”
A study on tuning the bandgap of metal halide perovskite nanocrystals. This work was a collaboration with the Abolhasani group here at NC State.

The link to the article: https://doi.org/10.1021/acscentsci.5c01651

We are excited to announce that Azka Arshad has been awarded second place in NC State’s 2025 Three Minute Thesis (3MT) competition, earning a $750 prize. The 3MT challenges graduate students to communicate their research clearly and compellingly in just three minutes using a single static slide.

Azka’s presentation highlighted her collaborative work between the Castellano and Abolhasani research groups to develop Roblonski, a microfluidic, material-efficient automated platform that accelerates foundational photochemical measurements. Traditional assays such as Beer–Lambert analyses, Stern–Volmer quenching, and photoluminescence quantum yield determination typically require large sample volumes, significant manual labor, and lengthy acquisition times. Roblonski miniaturizes, automates, and streamlines these processes, dramatically reducing the time, cost, and material consumption required to generate high-quality photophysical data.

Beyond solving longstanding bottlenecks in photochemistry labs, this work forms a cornerstone of the group’s involvement in the NSF-funded Center for Accelerated Photocatalysis (CAPs). By enabling high-throughput measurements that feed directly into AI-driven analysis and self-driving laboratory frameworks, Roblonski helps pave the way toward faster, greener, and more accessible discovery in photocatalysis and photochemical reaction development.

This achievement reflects Azka’s creativity, initiative, and commitment to advancing both scientific innovation and research accessibility. We congratulate her on this well-deserved recognition.

The North Carolina Photochemistry Symposium (NC Photochem) is an annual event that highlights natural and artificial photochemistry. The 2025 conference took place on Saturday, November 8, 2025, and was hosted by North Carolina State University (NCSU) in Raleigh, NC. Our group had the chance to show off what we’ve been up to, and our member, Azka Arshad, gave a talk to those in attendance as well!

Check out our most recent publication detailing “Plasmon-enhanced ultralow-threshold solid-state triplet fusion upconversion”

Read more here!
https://doi.org/10.1038/s41566-025-01783-1

Quantum phenomenon superfluorescence, a.k.a. an “optical bomb,” in perovskites opens the door to practical quantum technologies, such as sources of coherent quantum light operating at room temperatures. In a discovery that advances our understanding of quantum physics, an international team of researchers from École Polytechnique in France, the University of North Carolina, Duke University, and Boston University recently figured out why some materials are better at superfluorescence—a quantum phenomenon in which multiple excited emitters spontaneously synchronize their phases and emit a burst of coherent light. Quantum effects like entanglement that may accompany superfluorescence—except for ideal superradiant dynamics within the subspace of symmetric Dicke states—are extremely sensitive to external perturbations that cause it to quickly vanish. Very low temperatures enhance the phenomena, while high temperatures tend to do the opposite.

“Lead halide perovskites are crystalline semiconductors with a unique lattice structure and exceptional optoelectronic properties, which make them a promising platform to explore collective quantum effects,” says Vasily Temnov, a CNSR researcher at École Polytechnique’s Laboratoire des Solides Irradiés (Irradiated Solids Laboratory; LSI). Collective quantum effects

The team’s work was motivated by a central question for quantum optics: Can collective quantum phenomena like superfluorescence persist within disordered materials and at high temperatures? “Traditionally, such effects have been observed within specially prepared atomic systems or at cryogenic temperatures,” says Temnov. “We wanted to explore how interactions and disorder influence quantum coherence within solid-state systems.”

Experimentally, the team used time-resolved photoluminescence measurements to track the real-time evolution of a quantum phase transition from incoherent exciton-polarons (quasiparticle in condensed matter physics) to a collectively coherent state. And they used the Monte Carlo wave function method to simulate these dynamics based on a theoretical model that captured the main interactions of the system.

It revealed the stabilization of macroscopic quantum coherence within solids at elevated temperatures, which addresses a long-standing challenge for condensed matter physics.

“This opens the door to practical quantum technologies, such as sources of coherent quantum light operating at room temperatures,” says Temnov. “We show experimentally and theoretically that nonlinear exciton-lattice interactions can drive self-organization and coherence. For quantum materials and quantum computing, this reveals a new paradigm for engineering coherent phases and suggests promising routes toward scalable, thermally robust quantum emitters and lasers based on self-organized soliton phases.”

The team’s biggest “aha!” moment hit when they “realized that phonon-mediated interactions don’t just lead to dephasing but can actually promote ordering,” Temnov adds. “We first saw this in the experiment when superfluorescence persisted at high temperatures. It was unexpected, given the fast thermal dephasing.”

A closer look at the data showed fluctuations of superfluorescent intensity at frequencies matching certain phonon modes within these materials, which suggests that interactions with the lattice play an important role. “This led us to run Monte Carlo wave function simulations to understand the quantum dynamics of the system,” Temnov says. “Even after including disorder and fast thermal dephasing, the simulations showed that phonon-mediated interactions between excitons help protect the system from decoherence and allow superfluorescence to emerge at high temperatures. The coolest part for us was that we could capture all the relevant interactions in a simple Hamiltonian (a mathematical function to describe the total energy of the system), and that this model was able to reproduce the experimental results. It was very exciting to see.”

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