Hyperbolic materials have attracted intense attention due to their unique capabilities, such as enhanced heat transfer,1 applications in cosmology research,2 and increased spontaneous emission in high-density photon states.3 In addition, hyperbolic materials offer fascinating optical phenomena, including negative refraction,4 nanoscale light focusing, amplified scattering, and superresolution imaging.5 These fascinating phenomena arise from the horizontal ($H$) and vertical ($Z$) components of the complex permittivity tensor, $\overrightarrow{\epsilon }=\mathrm{diag}[{\epsilon }_H,{\epsilon }_H,{\epsilon }_Z]$, which have opposite signs in hyperbolic materials. Previously, much research was conducted on hyperbolic metamaterials (HMMs)3 made from artificial structures and combinations of metals and dielectric materials, but recent advancements in materials science have further expanded the realm of hyperbolic materials, particularly highlighting previously undiscovered natural hyperbolic materials.6^–14 To fully exploit the potential of hyperbolic media and expand the available momentum space, the material unit cell should be significantly reduced, ideally down to the atomic scale.11 The discovery of natural hyperbolic materials formed by natural molecular arrangements in the visible range is particularly significant because they exhibit unique optical properties compared with artificially structured HMMs, whose unit cell size cannot be reduced to much less than a few tens of the free-space wavelength of visible light. In this regard, natural hyperbolic materials such as hexagonal boron nitride (hBN),7^–9 graphite,10^,12 and ${\mathrm{MgB}}_2$13 have recently garnered significant attention due to their hyperbolic dispersion (HD) in uniaxial crystalline structures. However, it is important to note that their HD does not operate in the visible light range.

The observed HDs of explored natural materials span a broad spectral range, mostly in the ultraviolet and infrared regions. Interestingly, among them, the organic hyperbolic materials (OHMs),15^,16 as organic semiconductors exhibiting unique HD, operate particularly well in the visible and near-infrared (NIR) spectral regions at room temperature. This is associated with the high exciton binding energy compared with room temperature thermal energy and large oscillator strength of Frenkel excitons.15^,17^–19 In addition, considering their composition of organic molecules, OHMs are known for their high biocompatibility, making them highly useful for superresolution bioimaging in the visible spectral range.5^,20 Moreover, their straightforward manufacturing process and high tunability16 contribute to their growing importance for developing inexpensive and customizable OHMs. In this context, OHMs are considered promising natural hyperbolic materials that can be used in various nanophotonic applications, including fluorescence engineering and superresolution bioimaging. For example, QQT(CN)4, which exhibits HD in the spectral range of 660 to 920 nm, has been studied to manipulate the photoluminescence lifetime of an organic dye.15 Regioregular-poly(3-hexylthiophene) (rr-P3HT), with an HD range of 350 to 560 nm, has been used for super-resolution optical microscopy to achieve image resolution below 40 nm.16 However, the performance of OHMs is still limited in particularly narrow optical bands of HD. For more diverse and useful applications, it is very important to expand the HD wavelength range of OHMs and explore candidate materials that can be used in various wavelength ranges. From this perspective, investigating the optical properties of polymers created from various combinations of building blocks that constitute OHMs and elucidating the mechanisms of HD based on their components and structures are key to unlocking broadband and multiband hyperbolic materials.

In this study, we predict for the first time, we believe, that self-assembled polymeric films consisting of conjugated polymers with alternating multiple assembly units can naturally support multiband HD and hyperbolic exciton-polaritons (HEPs). Through theoretical studies using first-principles calculations and in-depth discussions on the assembled structure-dependent optical properties, we propose that the HDs and HEPs in OHMs can be tuned by selecting appropriate assembly units constituting the OHMs. Furthermore, we have identified several new OHM candidates that exhibit low-loss HD properties, proving to be highly useful as cutting-edge optical media for nanophotonic applications. It suggests a high potential for optical engineering and superresolution bioimaging applications in broadband and multiband wavelength regions. The multiband HD tendency of conjugated polymers, achieved through various linkages in the structure of copolymer assembly units, is a crucial factor in obtaining broadband HEPs based on anisotropic exciton resonances. The strategy for designing molecular structures to achieve low-loss HD of OHMs is discussed.

Here, we focus on representative copolymers made by modifying the backbone unit of poly(3‐alkylthiophenes) (P3ATs), known for their excellent aggregation ability in organic solvents, which leads to anisotropic electronic and optical properties, crystallization, alignment, and strong absorption tendencies.21^,22 Previously reported OHMs15^,16 with single-band HDs were composed of polythiophene structures. To demonstrate multiband HD properties, alternating copolymers were intentionally selected as candidates. In particular, donor–acceptor (D-A) type polymers, which consist of alternating donor and acceptor moieties, were selected because it has been reported that D-A type polymers offer possibilities for optical property engineering.23^,24

Consequently, five conjugated polymers were selected as target copolymers, which are variations of D-A assembly units with thiophene (T) as the donor unit and benzothiadiazole (BT) as the acceptor unit.25 Specifically, the simplest target conjugated polymer is polythiophene-benzothiadiazole (PTBT), consisting of a single T and a single BT unit, along with its derivatives modified by inserting an additional T unit, bridges, and spacers. Those derivatives include poly(dithiophene-alt-benzothiadiazole) (PDTBT), poly(cyclopentadithiophene-alt-benzothiadiazole) (PCPDTBT), poly(cyclopentadithiophene-ethynyl-benzothiadiazole) (PCPDTEBT), and poly(cyclopentadithiophene-vinylene-benzothiadiazole) (PCPDTVBT), as shown in Fig. 1(b). The insertion of the bridge unit makes two T units of PDTBT to the cyclopentadithiophene (CPDT) unit of PCPDTBT. Similarly, the insertions of ethynyl and vinylene groups between the electron-donating CPDT unit and electron-withdrawing BT unit of PCPDTBT lead to PCPDTEBT and PCPDTVBT, respectively.25 Our target copolymers share similar D-A assembly units but differ in structural modifications, making them suitable for analyzing the effects of component variations on optical properties and HDs.

To investigate the relation between the optical properties of polymers and their constituent assembly units, the first-principles calculation method can be used as a powerful tool for estimating the theoretical dielectric functions of unexplored materials. For example, numerous studies have used density functional theory (DFT) calculation methods to reveal the relationship between the chemical structure and optoelectronic properties of organic polymer materials such as P3HT and PCPDTBT.24^,26^–29 Note that previous studies were conducted at the single-molecule level due to the high computational costs associated with the structural complexity of polymer thin-film structures. Single-molecule calculations typically face limitations in reflecting macroscopic properties due to short conjugation lengths, lack of intermolecular interactions, and structural constraints within film structures. These limitations pose challenges in predicting the HDs of various polymer materials, particularly for OHMs that exhibit layered lamella structures macroscopically. Therefore, prior to the start of the study, a well-defined protocol is required to determine the molecular crystal structure of polymer films.

Aiming to identify the most stable crystal structure for each copolymer, we implement various configurations accommodating up to four monomers per unit cell, considering the feasibility of DFT calculations. The variety of crystalline conformation prototypes is shown in Fig. 1(c). (See Fig. S1 in the Supplementary Material for more detail consideration.) Here, we focus only on the structural conformation in the in-plane direction, assuming that the effect of intermolecular interactions among out-of-plane stacking is negligible compared with polymer conjugation, as the interactions are primarily governed by van der Waals (vdW) forces. The structure with the lowest energy is then subsequently designated as the crystalline configuration for each conjugated polymer. For example, Fig. 1(d) displays the optimized structures from each prototype configuration for PTBT. As shown in Fig. 1(e), the corresponding polymerization energies ($\mathrm{\Delta }{E}_{\text{poly}}$) for these configurations reveal that type IV has the stablest structure. $\mathrm{\Delta }{E}_{\text{poly}}$ is defined as $$\mathrm{\Delta }{E}_{\text{poly}}=\frac{E_{\text{polymer}}-N_{\text{monomer}}·(E_{\text{monomer}}-2·{\mu }_{\mathrm{H}})}{N_{\text{monomer}}},$$where $E_{\text{polymer}}$ is the total energy of the crystalline structure of the conjugated polymer; $N_{\text{monomer}}$ is the number of monomers per unit cell; $E_{\text{monomer}}$ is the total energy of the single monomer structure, which is passivated with hydrogen in a vacuum; and ${\mu }_{\mathrm{H}}$ is the chemical potential of hydrogen extracted from a ${\mathrm{H}}_2\mathrm{O}$ molecule under O-rich conditions. The $\mathrm{\Delta }{E}_{\text{poly}}$ and stablest structures for other candidate copolymers are shown in Table S1 and Fig. S2 in the Supplementary Material.

The calculations are performed using the Vienna ab initio simulation package30 with the projector-augmented wave method with the generalized gradient approximation (GGA) by Perdew et al.31 For all calculations, we determined the energy cutoff and $\mathit{k}$-point sampling to satisfy the convergence criteria of free energy $<0.01\mathrm{eV}/\text{atom}$ and pressure $<10\mathrm{kbar}$. The frequency-dependent dielectric functions were calculated with the automatically generated $\mathit{k}$-point sampling with $0.02{Å}^{-1}$ spacing between adjacent $\mathit{k}$-points. The convergence of a $\mathit{k}$-spacing for the target material was confirmed through the static dielectric constant value and the wavelength of the first peak in the dielectric function (see Fig. S3 in the Supplementary Material). The vdW approximation was not employed because it tends to underestimate the lattice and volume in polymeric film structures, making it challenging to predict their reasonable structure at room temperature. In addition, we confirmed that the volume change resulting from the vdW correction32 influences the spectral range of HD, whereas the multiband HD properties remain preserved as shown in Fig. S4 in the Supplementary Material. For partial density of state (PDOS) calculations, the same $\mathit{k}$-point setting as the dielectric function calculations is employed to ensure a sufficiently dense sampling. We plotted the PDOS graphs using the tetrahedron method for a more precise comparison.

We first compute the bandgap of each conjugated polymer with GGA functionality, but GGA tends to underestimate the bandgap. On the other hand, hybrid functionality provides a more accurate description of the bandgap. However, the computational cost is significantly increased when a dense $\mathit{k}$-point setting is employed in fully hybrid functional calculations to compute dielectric function. To overcome the high computational cost and maintain a high level of accuracy at the same time, the Heyd–Scuseria–Ernzerhof (HSE06)33 hybrid functionality (0.25 of the fraction of Fock exchange) is adapted to correct bandgap energies without further structural relaxation.34^,35 Also, dielectric functions are shifted rigidly by the difference between the GGA bandgap and the HSE06 bandgap.

To analyze the light propagation within the OHM films, the three-dimensional finite-difference time-domain (FDTD) simulations were performed using a commercial software package (Ansys Lumerical FDTD). For the simulations, a 20-nm-wide slit was etched into a 500-nm chromium (Cr) layer, enabling light to pass exclusively through the slit. A 100-nm-thick OHM film was placed on top of the etched Cr layer to observe the light propagation within it. Antisymmetric boundary conditions were applied along the $x$ axis, symmetric boundary conditions along the $y$ axis, and perfectly matched layer boundary conditions along the $z$ axis. The permittivity of the OHMs was assigned values from DFT calculations. An $x\mathit{\text{-z}}$-plane two-dimensional electric field profile monitor was employed to assess the intensity profile of the propagating beam within the OHM film.

The frequency-dependent dielectric function for each structure is calculated using DFT calculations to investigate the relationship between the conformational variance and HD of conjugated polymers. To consider the semicrystalline aspect of experimental OHM films, the polymer packing in the film state is assumed as depicted in Fig. 2(a), using PCPDTVBT as an example. The calculated complex permittivity of PCPDTVBT is presented in Fig. 2(b), with the real part $[\mathrm{Re}(\epsilon )]$ shown by solid lines and the imaginary part $[\mathrm{Im}(\epsilon )]$ shown by dashed lines in the horizontal ($H$) and vertical ($Z$) directions. As the conjugation direction and $\pi \text{-}\pi$ stacking direction belong to the in-plane orientation, the value of the $H$-direction is determined by averaging the two values in the $x\mathit{\text{-y}}$ plane, and the value of the stacking direction is represented by the $Z$-direction value. The calculated permittivity data for all considered copolymers are shown in Fig. S5 in the Supplementary Material. These data are then converted into a low-loss material figure of merit [$\mathrm{FOM}=-\mathrm{Re}({\epsilon }_H)/\mathrm{Im}({\epsilon }_H)$] to quantify the HD performance of each conjugated polymer [Fig. 2(b)]. FOM is a value that can estimate the performance of OHMs, and it has successfully predicted the experimental HD of OHMs in a recent study.16 The large absolute value of negative $\mathrm{Re}({\epsilon }_H)$, compared with the positive value of $\mathrm{Re}({\epsilon }_Z)$, indicates that strong transitions primarily occur parallel to the in-plane ($H$-) direction within the given frequency range, causing the presence of HD. The magnitude of $\mathrm{Im}({\epsilon }_H)$ represents the amount of optical loss at the same frequency. As $\mathrm{Re}({\epsilon }_H)$ and $\mathrm{Im}({\epsilon }_H)$ correspond well with each other via the Kramers–Kronig relations, if the absorption response is sufficiently strong at a resonant frequency, there can be a specific frequency range where $\mathrm{Re}({\epsilon }_H)$ is negative, and at the same time, $\mathrm{Im}({\epsilon }_H)$ is relatively small. This occurs because $\mathrm{Im}({\epsilon }_H)$ decreases faster than $\mathrm{Re}({\epsilon }_H)$ as the frequency moves away from the resonant frequency. In other words, such a frequency range is the low-loss HD spectral range.36

Figure 2(c) shows FOMs for conjugated polymer series confirmed to exhibit HD in the energy range from 0.5 to 3.5 eV. The FOM of rr-P3HT16 is also recalculated using the same computational setup as a reference. In the previously reported study, rr-P3HT, consisting of repeating units with a single T, already showed the highest FOM in the visible spectral range among all previously reported hyperbolic materials, including hyperbolic metamaterials,16 with a peak FOM of 0.59 at 562 nm. Interestingly, the newly explored polymers assembled with D-A units exhibit even higher FOM peaks and a wider range of FOM than those of rr-P3HT.

For example, PTBT, composed of electron-donating T units and electron-withdrawing BT units, shows HD in the range from 1.48 to 2.18 eV (569 to 836 nm), with the highest peak being 0.63 at 735 nm. Although PDTBT shows lossy HD ($\mathrm{FOM}<0.3$) in the NIR range, PCPDTBT, formed by inserting a bridge unit into the dithiophene unit of PDTBT, exhibits significantly improved HD, specifically low-loss HD ($\mathrm{FOM}>1$). Excitingly, D-A copolymers with spacers, such as PCPDTEBT and PCPDTVBT, exhibit extraordinarily low-loss multiband HDs. PCPDTEBT shows a significant FOM peak of 2.08 at 946 nm within the HD range from 0.90 to 2.82 eV (439 to 1387 nm). Particularly impressive is PCPDTVBT, which covers the widest HD range from 0.57 to 2.67 eV (464 to 2172 nm), spanning the visible to NIR regions. It has the highest FOM peak of 2.72 at 1136 nm. The discovery of new OHMs exhibiting high FOM and performing well across various multiband wavelength ranges, achieved by combining different assembly units, demonstrates the high potential of utilizing OHMs in diverse research applications to implement cutting-edge optical devices. To verify the validity of these results, we conducted additional experiments using one of the proposed OHMs, PCPDTBT, which is commercially available (see Fig. S6 in the Supplementary Material). The measured complex permittivity spectra closely align with theoretical predictions, exhibiting dual-band HD characteristics, which provide strong evidence for the feasibility of our approach. We also confirmed that PCPDTBT adopts a lamellar structure, as proposed in Fig. 1(a), based on the measured complex permittivity and X-ray diffractograms.

Aiming to uncover the relationship between the structures and the optoelectronic properties, Fig. 3 and Fig. S7 in the Supplementary Material provide a detailed analysis of copolymers by calculating the band structure, PDOS for carbons, and complex permittivity. In particular, the effects of inserting a bridge unit into the dithiophene and inserting a spacer unit between the D-A units on the optical properties are analyzed. First, to investigate the influence of the bridge unit, we compare the optoelectronic properties of PDTBT and PCPDTBT shown in Figs. 3(a) and 3(b), respectively. In the case of PDTBT, with its additional electron-donating T unit compared with semiconducting PTBT (see Fig. S7 in the Supplementary Material), it exhibits a metallic band structure. This leads to a slightly negative region in $\mathrm{Re}({\epsilon }_H)$. Incorporating a bridge unit into PDTBT, creating PCPDTBT, opens a bandgap of 1.06 eV and flattens its band structure. This change is also reflected in the PDOS data of PCPDTBT, which reveals that the electrons of the carbons in the T and BT units—dispersive in PDTBT—become relatively localized at lower energy levels due to the bridge insertion. At the same time, the negative region of $\mathrm{Re}({\epsilon }_H)$ expands, leading to a broader range of HD.

Next, we investigate the influence of spacer units between donor and acceptor units by comparing the properties of PCPDTBT, PCPDTEBT, and PCPDTVBT [Figs. 3(b)–3(d)]. When ethynyl and vinylene spacers are introduced to PCPDTBT, the bandgaps of PCPDTEBT and PCPDTVBT are both reduced to 0.66 and 0.34 eV, respectively. Contrary to the bridge unit incorporation, PDOS of the spacer-implemented structures reveals that the electrons from the spacers are delocalized over a wide energy range, contributing to the bandgap reduction and the band dispersion enhancement. For the complex permittivity, adding spacers results in a redshift of the optical transition energy in the $H$ direction and a significant expansion of the negative region of $\mathrm{Re}({\epsilon }_H)$, with an increase in its absolute value. As a result, the HDs of PCPDTEBT and PCPDTVBT are improved in longer wavelength ranges, indicating their potential as outstanding hyperbolic materials operating effectively across the visible to NIR range. This systematic comparison and analysis demonstrate that the desired HD within specific wavelength ranges can be achieved by strategically selecting and modifying the assembly units in conjugated polymers.

To demonstrate that the explored OHM candidates can be useful hyperbolic materials for actual photonic applications, the propagation of high spatial frequency hyperbolic polaritons (high-$k$ HPs)5^,37 is simulated using the FDTD method, as illustrated in Fig. 4 and Figs. S8 and S9 in the Supplementary Material (see Sec. 2 for the simulation details). The applicability of OHMs can be easily assessed by confirming the presence of highly directional high-$k$ HPs within the OHMs. The wavelength-dependent propagation half-angles $\theta (\lambda )$ of HPs shown in Figs. 4(a)–4(f) are determined by the expression for $\tan \theta =\sqrt{-\mathrm{Re}({\epsilon }_H)/\mathrm{Re}({\epsilon }_Z)}$.37 The HPs observed in PCPDTEBT were calculated at 946 nm [Fig. 4(a)], 578 nm [Fig. 4(b)], and 466 nm [Fig. 4(c)]. These wavelengths correspond to the three wavelengths where a high FOM was observed, as shown in Fig. 2(c). In the same way, the HPs seen in PCPDTVBT were calculated by selecting a wavelength of 1136 nm [Fig. 4(d)], 670 nm [Fig. 4(e)], and 518 nm [Fig. 4(f)]. The results clearly show that the tightly focused high-$k$ HP is directed within the PCPDTEBT and PCPDTVBT, demonstrating that subwavelength light is confined on the OHM surface. Although these high-$k$ optical modes are diffused throughout the entire region and cannot propagate long distances in glass [Fig. S8(a) in the Supplementary Material], subwavelength optical confinement can be achieved in OHMs due to their HD properties.38^,39 In addition, the spatial confinement of the HP formed in PCPDTVBT at 1136 nm, indicated by the white arrow in Fig. 4(d), is $\sim 100\mathrm{nm}$, which is 11 times smaller than the wavelength, demonstrating the low-loss HD characteristics and a high FOM of the OHM. As shown in Fig. 2(c), the FOM of PCPDTVBT at $\lambda =1136\mathrm{nm}$ is higher than that of PCPDTEBT at $\lambda =946\mathrm{nm}$, indicating that the propagation capability of the high-$k$ HPs in PCPDTVBT at $\lambda =1136\mathrm{nm}$ is better.

The OHMs with multiband hyperbolic characteristics proposed in this study have low optical losses and are less prone to serious defects during manufacturing, unlike conventional HMMs created with artificial multilayer structures. Thus, they can be free from unwanted internal scattering and loss of light. This makes them suitable for enhancing the radiation efficiency of quantum emitters40 or for applications such as broadband beam splitters,41 deep subwavelength interference nanolithography,42^,43 hyperlenses,44 and near-field optical imaging and focusing.37

In practical fabrication and applications, the HD performance of polymer films depends on their crystallinity because the polymer chains are not infinitely extended in the actual film structure. Moreover, when the polymer chains are entangled, they bend and twist, meaning the effective conjugation length can be proposed in the computational setup to show the HD properties that can be easily realized in practice.45^,46 Lee et al.16 have shown that calculating of an oligomer structure with proper effective conjugation length can successfully predict the experimental HDs of OHM films with different crystallinity. To examine the dependence of HD properties on effective conjugation lengths, we set the effective conjugation length of our candidate polymers to $\sim 22Å$, ensuring that the calculated complex permittivity is well matched with that of the most outstanding rr-P3HT sample16 (see Fig. S10 in the Supplementary Material for oligomer structures of each conjugated polymer with the considered effective conjugation length). The oligomer structure is created through hydrogen passivation, as shown in Fig. 5(a), using PTBT as an example. By comparing the calculated bandgaps, as shown in Fig. 5(b), the oligomer structures exhibit a blueshift compared with the crystalline structures. We also calculate the FOM for each oligomer structure, as shown in Fig. 5(c). The calculated complex permittivities of oligomer structures are shown in Fig. S5 in the Supplementary Material. Notably, ${(\mathrm{PCPDTBT})}_{m=2}$ oligomer shows no HD behavior, which implies that the synthesizing conditions will largely affect the HD properties of PCPDTBT films. On the other hand, PCTDTVBT and PCPDTEBT maintain relatively high FOM values even in the oligomer state, although the frequencies of the highest peaks change, as their bandgaps are largely dependent on the effective conjugation length. These observations suggest that the tunability of HD through crystallinity control varies among different polymers.

In this study, we propose self-assembled low-loss multiband OHMs explored by first-principles calculations for the first time, to our knowledge. As target materials, we explore D-A copolymers composed of T and BT and their derivatives by determining the stablest crystalline polymer film structures and calculating the corresponding frequency-dependent dielectric function to evaluate their HD performances. As a result, we predict that PCPDTEBT and PCPDTVBT, which contain spacers between D-A units, exhibit extraordinary multiband HD. The electronic structures of these copolymers show that the bridge enlarges the bandgap by localizing valence electrons at low energy levels, whereas the spacers reduce the bandgap, promoting the dispersion of electrons. From the perspective of HD, the insertion of both the bridge and spacer results in enhancements of HD in the visible range. As a result, PCPDTEBT and PCPDTVBT not only possess cutting-edge HD properties but also offer multiband functionality, exhibiting outstanding FOM that covers a wide range of visible light with low optical loss. Consequently, the proposed OHMs exhibit not only uncharted HD properties but also excellent tunability in optical properties through the addition of bridge or spacer units to the main backbone structure, allowing for high FOM values across desired wavelength ranges through modifications of assembly units and film crystallinity. By leveraging the Stark effect,47^–49 which is readily observable in such copolymer-based materials, there is potential for reversible tuning and control of optical properties. This aspect will be explored in greater depth in our follow-up studies.

The potential of the explored OHMs for applications in deep-wavelength lithography, hyperlenses, near-field focusing, and superresolution imaging was confirmed through calculations of volumetric confinement and propagation of high-$k$ HPs with FDTD simulations. Furthermore, to investigate the tunability of HD through crystallinity control, we designed oligomer structures of each OHM with limited effective conjugation lengths. As expected, all oligomers exhibit a blueshift from their polymer bandgap, the magnitude of which varies from oligomer to oligomer. Consequently, the proposed OHMs exhibit not only uncharted HD properties but also excellent tunability, allowing for high FOM values across desired wavelength ranges through modifications of assembly units and film crystallinity.

Suim Lim is a PhD candidate in the Department of Mechanical Engineering at Sogang University. She is an academic research student in the Energy AI & Computational Science Laboratory at the Korea Institute of Energy Research. She received her BS degree in mechanical engineering from Chungnam National University. Her research interests focus on studying optoelectronic devices and catalysis with organic materials using first-principles calculations.

Dong Hee Park is currently a graduate student in the Department of Physics at Chungbuk National University. He received his BS degree in physics from Chungbuk National University in 2023. His current research interests are focused on developing optical imaging and sensing technologies. He is focused on creating miniaturized optical systems using three-dimensional printing, which enables the real-time identification of microplastics.

Bin Chan Joo is currently a graduate student in the Department of Physics at Chungbuk National University. She received her BS degree in physics from Chungbuk National University in 2023. Her research interests are focused on studying light–matter interaction and strong coupling between excitons and plasmons. She is focused on optically visualizing light–matter interaction systems with high spatial resolution.

Yeon Ui Lee is an associate professor at Chungbuk National University. She received her BS degree in physics in 2010 and her PhD in optics in 2015 from Ewha Womans University. From 2017 to 2021, she was a postdoctoral fellow at the University of California, San Diego. Her current research interests include organic metamaterials, molecular plasmonics, and three-dimensional superresolution optical microscopy.

Kanghoon Yim is a principal researcher in the Energy AI & Computational Science Laboratory at the Korea Institute of Energy Research. He received his MS and PhD degrees from Seoul National University in 2013 and 2017, respectively. His research activity involves various applications such as photovoltaics, optoelectronics, rechargeable batteries, and catalysis using first-principles calculations, molecular dynamics, and data-driven materials design.