The A-site cation in lead-halide perovskite nanocrystals (NCs) plays a pivotal role in fine-tuning their structural and electronic properties. The presently available chemical space remains minimal since, thus far, only three A-site cations, cesium, formamidinium, and methylammonium, have been reported to favor the formation of stable lead-halide perovskite NCs. Inspired by recent reports on bulk single crystals with aziridinium (AZ) as the A-site cation, we present a straightforward colloidal synthesis of AZPbBr₃ NCs with a narrow size distribution and size tunability down to 4 nm, producing quantum dots (QDs) in the regime of strong quantum confinement. NMR and Raman spectroscopies confirm the stabilization of the AZ cations in the locally distorted cubic structure. AZPbBr₃ QDs exhibit bright photoluminescence with quantum efficiencies of up to 80%. Stabilized with cationic and zwitterionic capping ligands, single AZPbBr₃ QDs exhibit stable single-photon emission at both room and cryogenic temperatures, reduced blinking, and high single-photon purity, comparable to the best-reported values for MAPbBr₃ and FAPbBr₃ QDs of the same size.

Beyond compositional engineering, QD shape engineering offers an additional and powerful tool for further fine-tuning and improvement of optical properties, allowing the manipulation of features that are inaccessible by keeping the shape isotropic. In the case of perovskite QDs, shape anisotropy can enable, for example, directional emission, spatial confinement of excitons in one or two dimensions, tuning of exciton fine structure, and radiative decay. To systematically explore shape-dependent properties of one-dimensional CsPbBr3 perovskite structures, we developed a synthetic approach toward stable, size- and shape-uniform nanorods with tunable thickness (5-24 nm) and aspect ratio (1-16, larger for thinner nanorods). By exploiting the difference between {110} and {001} facets of the orthorhombic perovskite structure, we achieved precise control over nanorod morphology. With the use of ligands providing sufficient stability, we performed comprehensive optical characterization, paving the way for advanced optical functionalities in perovskite nanostructures.

For semiconductors, precise tuning of the bandgap holds the key to unlocking technologies. For halide perovskites, such tunability is possible by alloying halides into effective solid solutions. But what are the stability boundaries of such a mixture? In metallurgy, Hume-Rothery rules ascribe the radius ratio of cations to anions as a guiding principle for stability, which also holds for oxide-perovskites. We use lead halide perovskite nanocrystals as a model system to experimentally validate the boundaries of crystal stability and contrast it with the fundamental theories. We base the experiment on the ability to conduct halide exchange post-synthetically, effectively tuning their composition from single-halide into ternary solid solution alloys. The halide composition determines the band-gap, and a spectroscopic readout is used to interrogate the resulting crystals. To map such a vast space of composition and sizes, thousands of exchange reactions were conducted. To execute such vast experimental task a high-throughput robotic anion exchange and spectroscopic process was developed. We mapped the size-dependent behavior across the ternary halide composition of these materials by synthesizing and spectroscopically characterizing over 3000 successful experiments. The resulting maps allow for the first time to point to a stable ternary CsPb(ClₓBr_yI_z)_₃ halide perovskite domain. We showcase the stabilizing effect surface energy has on ternary solid solution compositions, and that smaller nanocrystals demonstrate a smaller miscibility gap. The vision is to extend our understanding of sable perovskite compositions also to bulk, influencing the design of future optoelectronic devices.

Ordered arrays of nanocrystals, called supercrystals, have attracted significant attention owing to their unique collective quantum effects arising from the coupling between neighboring nanocrystals. In particular, lead halide perovskite nanocrystals are widely used because of the unique combination of the optical properties and faceted cubic shape, which enables the formation of highly-ordered supercrystals. The most frequently used method for the fabrication of perovskite supercrystals is based on self-assembly of nanocrystals from solution via slow evaporation of the solvent. However, the supercrystals produced with this technique grow in random positions on the substrate. Moreover, they are mechanically too soft to be easily manipulated with microgrippers, which hinders their use in applications.

This presentation will detail how mechanically robust supercrystals built from cubic lead halide perovskite nanocrystals are synthesized that can easily be relocated over macroscopic distances into positions and substrates of choice. X-ray nanodiffraction provides details about the local structure of the supercrystals, and fluorescence laser scanning microscopy under applied bias reveals the effect of strong electric fields on the (collective) optical properties of the supercrystals.

X-ray imaging technologies play a vital role across a wide range of fields, from materials science and high-energy physics to medical diagnostics and security screening. However, conventional imaging screens are hindered by their rigidity, brittleness, and high cost, making them unsuitable for the growing demand for flexible, eco-friendly, and cost-effective imaging solutions.

In this work, we introduce a systematic study on the synthesis and fabrication of highly efficient and stable zero-dimensional (0D) Mn²⁺-activated organic–inorganic zinc halide systems. By utilizing two carefully selected organic spacers, we engineered a series of 0D luminescent systems exhibiting intense green emission, with photoluminescence quantum yields (PLQY) reaching up to 98%. Comprehensive experimental and theoretical studies were conducted to uncover the mechanisms underlying their optical response and to examine the long-term stability of these 0D systems.

Moreover, the radioluminescence and scintillation performance of the 0D Mn²⁺-activated organic-inorganic zinc halide systems were evaluated to identify the factors influencing their efficiency. Our rational design approach led to an improved light yield of up to 31,000 photons/MeV and an ultralow detection limit of only 112 nGy/s, which is 50 times lower than the dose typically required for standard medical diagnostic procedures. To test their practicality for real-life applications, the scintillators were embedded in flexible PDMS matrices, enabling the capture of high-resolution X-ray images of various objects.

This work presents a promising path toward the development of flexible, scalable, and high-performance Mn²⁺-activated orgnic-inorganic zinc halide screens for next-generation X-ray imaging technologies.

Colloidal nanocrystals (NCs) have inorganic cores and organic or inorganic ligand shells. They are prized for their size- and shape-dependent properties and serve as building blocks of artificial materials and unconventional devices. Here, we describe NC-based, three-dimensional optical metamaterials constructed using imprinting techniques single- and multiple-types of metal, metal oxide, and semiconductor NCs. We focus on the chemical and thermal addressability of NCs, i.e., the ability to select, exchange, strip, or add atoms, ions, and molecules during or post-deposition, that is not accessible in bulk materials, and allows the control of metamaterial structure and properties. Through ligand engineering we tailor the dielectric function of metal NC assemblies through an insulator-to-metal transition.¹ By juxtaposing NC assemblies and bulk thin films to make bilayer heterostructures, we exploit ligand exchange to trigger folding of two- into three-dimensional structures,² which we use to achieve broadband^3,4 and reconfigurable⁵ 3D chiral optical metamaterials and 3D chiral luminescent materials.

Mastering light-matter interaction lies at the heart of quantum technologies – the Purcell effect, for instance, has been instrumental in generating indistinguishable photons with high quantum efficiency [1]. A promising frontier in this field aligns towards the chiroptical regime which may unlock unconventional nonreciprocity and chiral quantum photonics [2,3], while achieving a full control over single-photon chirality remains a major challenge. Here, we demonstrate a highly efficient chiral single-photon source by transducing the strong local optical helicity of the gold helicoid into a single perovskite quantum dot (PQD) that serve as a nanoprobe, in a non-invasive and non-averaged manner. By fine-tuning the near-field coupling and the excitonic and plasmonic spectral resonances, we achieved single-photon chirality as high as 80% and an excitation dissymmetry factor reaching 90%, achieving a full optical chirality (excitation-emission) with a near-unity efficiency. These results are accompanied by rapid radiative decay (~300 ps) and a Purcell enhancement factor of approximately 3. Electromagnetic simulations reveal that chiral field enhancement arises from circulating surface currents unique to the helicoid nanogeometry. Furthermore, we present a prototype of a switchable circular dichroism probe that leverages excitation-wavelength-dependent enantiospecificity. Our results set a new benchmark in solid-state chiral quantum light sources and offer a versatile platform for next-generation on-chip quantum photonics and nanoscale chiroptical sensing.

Photonic architectures offer a promising avenue for optimizing the performance of various optoelectronic devices. Nevertheless, the future of optoelectronic devices hinges on cost-effective and large-scale manufacturing techniques that can reduce expenses and boost production efficiency. To harness the remarkable attributes of photonic structures for enhancing these devices, they must undergo a processing approach akin to that of the devices themselves.

In our research group, we employ soft nanoimprinting lithography, a versatile, rapid, and cost-efficient method for crafting nanostructures from a diverse variety of materials. In soft nanoimprinting lithography, we make use of pre-patterned soft elastomeric stamps to fabricate photonic structures out of materials such as resists, biopolymers, colloids and nanomaterials in general. In all cases, the resulting photonic architectures can exhibit a resolution below 100 nm while covering areas up to 1 cm².

During this presentation, I will demonstrate our utilization of pre-patterned stamps to induce the long-range alignment of different colloids, including gold colloids and perovskite nanocrystals, to attain distinct optical properties, such as lattice resonances with high Q-factors. Moreover, I will showcase how elastomeric molds pre-patterned with chiral motifs can lead to chiral 2D arrays, exhibiting strong circular dichroism and intense circularly polarized photoluminescence (CPL) combined with a wide range of emitters, making them seamlessly applicable in various practical applications.^1,2

1.             Qi, X. et al. Chiral plasmonic superlattices from template-assisted assembly of achiral nanoparticles. Nat. Commun. 16, 1687 (2025).

2.             Mendoza-Carreño, J. et al. A single nanophotonic platform for producing circularly polarized white light from non-chiral emitters. Nat. Commun. 15, 10443 (2024).

The design of dendrimers and pro-mesogenic ligands enables new strategies to create nanocrystals (NC) liquid crystal hybrids. The use of these supramolecular ligands systems can direct the assembly of nanocrystals (NCs) is to 3 dimensionally ordered superlattices allowing multicomponent and the multiscale organization of nanocrystals (NCs) with controlled composition, size, and shape. These NCs, acting as 'artificial atoms' with tunable electronic, optical, and magnetic properties, pave the way for the development of a new periodic nanomaterials. The resulting superlattices are ideal building blocks for incorporation into new thin films, and integrated devices. The scalability of this process ensures its feasibility for large-scale applications. It is possible to control the formation and phase transformations in deposited NC superlattices by adjusting the thermal energy of a nanocrystal dispersion. These structural changes can allow the solids to anneal an improve their organization post-deposition. The modular assembly of these NCs allows the desirable features of the underlying quantum phenomena to be captured stimuli-responsive thin films.

Topochemical reactions are chemical reactions of solids that enable transforming their chemical compositions and crystal structures, with short movements of the constitutive atoms. When applied to nano-objects, these approaches enable to reach complex compositions, heterostructures and shapes.[1] Topochemical reactions of nano-objects however rely on colloidal syntheses below 300 °C in usual solvents, which limits their use to ionic or metallic objects. Post-modifications of more covalent materials would pave the way to specific properties, related to (electro)catalysis, magnetism, and hardness, for instance, but they require higher temperatures.[2-4] In this work, we will show how to trigger and control topochemical reactions of covalent nanoparticles by using liquids stable at relatively high temperatures, thereby giving access to new compositions. We will focus on molten salts as thermally stable liquids, and focus on topochemical reactions involving both cation exchange and galvanic replacement.

Cation exchange in indium pnictide nanocrystals dispersed in molten KGaI₄ and KAlI₄ has been very recently unveiled to tune the optical properties of these III-V nanocrystals.[1,2] With the aim of targeting more covalent materials and possibly modulating (electro)catalytic properties versus CO₂ and CO electroreduction (CO₂R and COR), we have focused on cation exchange on CuSi₂P_3. This compound crystallizes in a distorted zinc blende structure composed of corner-sharing [CuP₄] and [SiP₄] tetrahedra.[5] The material encompasses Cu⁺ cations in a covalent [Si₂P₃]^- framework. It shows high performances as electrocatalyst for COR into acetate. We hypothetize that partial exchange of Cu⁺ and Si by Zn²⁺ and Ga^3+/2+/+ would enable adjusting the catalytic selectivity and activity, also probably impacting optoelectronic properties. The existence of zinc blende-related Zn_1.5Si_1.5P₃, and Ga_1.5Si_1.5P₃ [6,8] with [MP₄] (M=Zn or Ga) and [SiP₄] tetrahedra hints at the possibility to exchange Cu and Si in CuSi₂P₃ nanoparticles.

In this talk, we will demonstrate successful topochemical reactions of covalent silicophosphide nanoparticles in molten salts.  By using synchrotron radiation-based in situ X-ray diffraction, during the reactions in molten salts, we unveiled minute scale transformations of CuSi₂P₃ into Zn_1.5Si_1.5P₃ or into a bimetallic copper zinc silico-phosphide (Cu_0.9Zn_0.2Si_2.0 P_2.4) by reaction with Zn²⁺ precursors. The selectivity of the reaction can be tune by adjusting the amount of Zn reagent. On the other hand, we succeeded to react CuSi₂P₃ nanoparticles with different gallium precursors (GaCl₃, GaI₃ and Ga₂I₃ [2]) to yield bimetallic copper gallium silicophosphides Cu_0.8Ga_0.2Si_2.0P_2.3, Cu_0.6Ga_0.4Si_2.0P_1.9 and Cu_0.7Ga_0.4Si_2.0P_2.2 via a similar process. Partial substitution of Cu by Zn or Ga into the silicophosphide is accompanied by a phase transition from a cubic structure to a tetragonal one. TEM confirmed that the morphology and size of the particles did not evolve significantly, while TEM-EDS mapping confirmed the homogenous distribution of the elements at the particle scale. EXAFS at the Cu-K edge showed the preservation of [CuP₄] tetrahedra, while EXAFS at the Ga-K and Zn-K edges indicated the formation of [ZnP₄] and [GaP₄] tetrahedra, as expected for an exchange reaction, which was confirmed by solid-state ³¹P, ⁷¹Ga and ²⁹Si NMR. XANES demonstrated that cationic exchange with Zn or Ga is accompanied by galvanic reactivity, initial Cu⁺ gets oxidized to an average oxidation state Cu^1.5+ meanwhile Ga and Zn species are reduced during the topochemical reaction.The evaluation of the electrocatalytic properties of these new bimetallic silicophosphides for CO reduction is under way.

In the current context of escalating climate change and all of its related problems, innovative solutions are needed through the whole range of energy related technologies. In its specific field, smart windows devices stand out for their ability to reduce energy consumption and CO₂ emissions by controlling dynamically the light and heat transmittance in buildings. In this context, nanostructured TiO₂ crystals (NCs) emerge as a versatile platform because of its excellent energy conversion and electrochromic properties.

In our group, one of the research lines exploits the aliovalent doping of the nanostructured TiO₂ crystals to improve their electrical conductivity, specific capacitance and their ability to modulate optical transmittance further and in a more selective manner: in previous works V- and Nb-doped TiO₂ nanocrystals have already been successfully synthetized and deeply characterized to unveil the role of the dopants^1,2.

In my contribution, I will present the results coming from the synthesis and in situ characterization of the TiO₂ nanocrystals doped with W: the amount of doping (10%) is based on previous studies where the optimization of the localized surface plasmon resonance (LSPR) properties was addressed3. The successful synthesis was proved by Raman microscopy and XRD, which confirmed the presence of the anatase phase and effective W-doping. An UV-VIS-NIR absorption spectrum showed that the LSPR absorption mechanism is present in NIR region for these NCs. NCs thin films were prepared by doctor blading an organic viscous and then calcinating it. The morphology of the films is characterized by FESEM and also TEM images were taken, from which is clear that the NCs have an average diameter of 5nm.

The electrochemical properties were tested through a set of cyclic voltammetries at different scan rates from which it is evident a change in the current shape of the redox pair and an increase in the charge capacitance of the W doped TiO₂ NCs, resulting in an improvement of the electrochemical behavior.

The spectroelectrochemical behavior was tested through UV-VIS absorption measurements at different applied voltages: the LSPR and plasmonic light absorbing mechanisms characteristic of this W doping are revealed, resulting in a partial filtration of the light spectrum. This suggests its potential in smart windows applications.

Finally, a deep in situ analysis comprehending x-ray absorption spectroscopy (XAS), x-ray photoemission spectroscopy (XPS) spectro-electrochemistry (SEC) electrochemical impedance spectroscopy (EIS) techniques have been used to characterize the real-time electronic and structural changes during operation allowing to give insights into the electrochemical reaction mechanisms.

The precision of nanocrystal shapes is crucial to tailor the functionalities of nanomaterials. Traditional molecular dynamic simulations are computationally too expensive to unveil the multiscale nature of nanocrystal synthesis from the potential energy of an atom to the mesoscales of a nanocrystal composed of tens of millions of atoms. To overcome this issue, we implement rejection-free kinetic Monte Carlo simulations using the semi-Gibbs ensemble sampling solid-to-liquid energy variations to grow and dissolve atoms at the nanocrystal surface. This allows the simulation of realistically sized nanocrystals coupled with the energetics of atoms. We discuss the growth of symmetry-preserving shapes, such as cubes, octahedra, rhombic dodecahedra, and their truncations. We show the importance of surface site kinetics associated with adatom nucleation on facets of different crystallographic directions, leading to the entrapment of nanocrystal shapes in metastable equilibrium. We then discuss the spontaneous symmetry breaking of shapes due to the dynamics of surface defects. The multiscale simulations reproduce the emergence of nanocrystal shapes inaccessible to other computational tools.

Lead halide perovskite quantum dots (QDs) have emerged as highly promising candidates for next-generation photodetectors (PDs). However, a significant limitation lies in the weak binding of conventional long-chain ligands on the QD surface, which compromises both charge transfer efficiency and material stability. In this study, we introduce a novel approach involving the partial substitution of these long-chain ligands with shorter, aromatic alternatives, specifically phenylethylamine (PEA) and trans-cinnamic acid (TCA). We investigated the impact of this ligand engineering on the performance of CsPbBr3 QDs-based photodetectors fabricated on flexible textile substrates. Our results show that devices with optimal concentrations of PEA (L-type) and TCA (X-type) and TCA doping exhibit markedly improved performance compared to the control device, which we attribute to enhanced conductivity, a longer photoluminescence lifetime, reduced surface defects, and minimized non-radiative recombination. The PEA-treated device displayed superior blue-light photodetection, achieving a peak responsivity of and an external quantum efficiency (EQE) of 41.3%. Furthermore, the devices demonstrated excellent mechanical flexibility, maintaining high performance even after 500 bending cycles.

Nanocrystal-based solids represent a versatile class of materials whose collective properties can be finely adjusted by tuning parameters such as shape, size, chemical composition, and surface ligands. These materials are particularly relevant for advancing plasmonic, optoelectronic, and thermoelectric technologies. Controlling thermal transport within such systems is crucial, as local heating—whether induced by optical absorption or electrical current—can impair performance, cause instability, or trigger undesirable reactions. In this contribution, I will discuss recent findings on the heat transport properties of superlattices composed of gold nanospheres, nanorods, and nano-bipyramids. Using correlative scanning electron microscopy and spatio-temporally resolved thermoreflectance techniques, we accessed thermal dynamics with nanosecond resolution and sub-micron spatial detail. In polymer-ligand-capped gold nanosphere assemblies, we observed that monolayer configurations exhibit faster thermal diffusion compared to multilayers. Monte Carlo simulations incorporating quasi-ballistic phonon transport suggest this behavior arises from the interplay between extended phonon mean free paths and ligand interdigitation. In assemblies of gold nanorods and bipyramids, our results show that heat preferentially propagates along the nanoparticles’ longitudinal axis, maintaining directional flow even in bent or curved configurations. In ordered superlattices, this results in pronounced anisotropic heat conduction, with higher diffusivity along the particles' elongation. Finite element analysis and effective medium theory confirm that this directional transport can be tuned by modulating particle shape, aspect ratio, and packing geometry. Harnessing such anisotropy offers new strategies for improving heat dissipation and directing thermal flow within functional devices, all while preserving tunable optical and electronic properties.

The synthesis and characterization of thin-film plasmonic supercrystals of gold nanoparticles will be discussed.[1,2] The dense packing of the nanoparticles in the supercrystals leads to emergent optical properties due to extreme light-matter interactions.[3] The resulting enhanced near-fields in the structures can be exploited for surface-enhanced spectroscopies but also for plasmonic photocatalysis. [4,5] Towards such applications it is, in turn, also important to understand the thermal properties of the materials on relevant timescales.[6,7] The correlation of electron microscopy, spectroscopy and small-angle X-ray-scattering helps to understand how nanoparticle surface chemistry affects structure formation and how structure dictates the emerging properties. This is in particular interesting for anisotropic nanoparticles where the interplay of shape anisotropy and ligand properties leads to interesting new structures and near-field distributions which can be related to polarization-dependent optical properties.[8] With binary mixtures even more complex geometries can be obtained, providing plenty of room to explore for these polaritonic materials. 

Heterostructured nanocrystals (NCs), such as core-shell architectures, are often designed and synthesized under kinetically controlled conditions. However, in any realistic application, be it in optoelectronics, catalysis, or energy conversion, these NCs will inevitably be exposed to thermal or other energetic inputs. Understanding how they structurally evolve in response to such stimuli is, therefore, not only scientifically relevant but essential for predicting and engineering functional performance.

In this talk, we explore the temperature-driven transformations of NCs, both in solution and in the solid state, with a particular focus on heterostructured systems. Using a model metal-semiconductor core-shell system, we dissect how initial configurations, often kinetically trapped, undergo reorganization toward more stable, thermodynamically favored states. We discuss the mechanistic pathways that govern these transformations, highlight the key parameters influencing interfacial diffusion (such as bonding strength, lattice mismatch, and defect densities), and demonstrate how these can be tuned to direct the final NC architecture.

By bridging synthesis, in situ observation, and theory, we aim to provide a framework for understanding and controlling structural evolution in NC heterostructures under operational conditions.

High-temperature solid oxide electrochemical devices provide one of the most efficient, clean, and versatile platforms for hydrogen production and electric power generation. The formation of space charges at the interfaces within their multilayer structures has been intriguing, yet its nature remains poorly understood. Herein, we present an innovative electrode design that enables precise space charge tailoring using regularly arrayed nanocatalysts. Our study reveals that a local electron-rich region develops within the space charge zone of a pure oxygen-ion conductor, gadolinia-doped ceria (GDC), at its interface with electronically conductive (Sm, Sr)CoO₃ (SSC) nanocatalysts. We synthesized 20 nm-sized SSC nanocatalysts with well-defined geometries on a porous GDC scaffold using a highly controllable infiltration technique. When the interparticle distance decreased below a critical threshold, the local electron-rich regions overlapped, forming an extremely narrow yet continuous electron-conduction pathway throughout the ion-conducting matrix. This approach provides a well-balanced electronic and ionic conduction network along with a highly active surface enriched with nanocatalysts. Consequently, full cells incorporating this space-charge-mediated electrode exhibited remarkable performance and stability in both hydrogen and electricity production modes, significantly surpassing state-of-the-art counterparts that rely on bulk conduction pathways. Furthermore, this method was successfully scaled up for commercial-scale large cells, demonstrating the practical viability of space-charge engineering for real-world applications.

Colloidal lead halide perovskites (LHP) nanocrystals (NCs) are popular light-emissive materials for optoelectronic devices, of interest for LEDs, LCDs, lasers and quantum light sources. Most studies on LHP NCs focus on relatively large NCs exceeding 10 nm in size, exhibiting weak to no quantum confinement effects. Recently, we showed that perovskite quantum dots (pQDs) can be synthesized using a newly developed synthesis route, resulting in pQDs that are tunable between 3 and 13 nm range.[1] Further exploring the tunability of these QDs, we extend the emission of these materials through coupling these pQDs to anchored luminescent dyes, allowing for efficient energy transfer.[2] To also enhance the charge carrier extraction, donor/acceptor molecules can be tethered to the pQD. These molecules must strongly bind to the ionic surfaces of pQDs without compromising colloidal stability. This is achieved by using multifunctional ligands containing a quaternary ammonium binding group for strong pQD surface attachment, a long tail group for colloidal stability, and a functional group near the pQD surface.[3] Such pQDs with ferrocene-functionalized ligands show fast photoexcited hole transfer with near-unity efficiency. Density functional theory calculations reveal how ferrocene’s molecular structure reorganizes following hole transfer, affecting its charge separation efficiency. This approach can also be extended to photoexcited electron and energy transfer processes with pQDs. Therefore, this strategy offers a blueprint for creating efficient pQD–molecular hybrids for applications like photocatalysis.

Semiconductor nanocrystals (NCs) exhibit quantum confinement effects that lead to highly tunable optical and electronic properties. This unique versatility has positioned NCs as key components for next-generation optoelectronic and photonic technologies. By controlling their size, shape, and composition, researchers are working toward a new “periodic table” of artificial atoms, enabling the rational design of materials from the bottom up.[1]

A major challenge - and opportunity! - lies in directing the assembly of these NCs into ordered superstructures that exhibit emergent, collective properties. Such artificial solids hold promise for applications ranging from light management to low-threshold lasing and energy-efficient photonic systems. However, the deterministic control of NC self-assembly remains limited by an incomplete understanding of interparticle interactions.[2]

In this talk, I will present a general strategy to bias the self-assembly of NCs into three-dimensional superstructures with well-defined morphology and high crystalline order. Using emulsion-templated assembly, we guide the formation of spherical supercrystals composed of densely packed, ordered NCs.[3] Time-resolved synchrotron X-ray scattering reveals a ligand-mediated hard-sphere-like crystallization mechanism,[4] yielding single-domain architectures approaching single-crystal quality.[5]

These superstructures exhibit multiscale optical functionality: while their refractive index is determined by the nanocrystal composition, their mesoscale geometry supports Mie resonances, leading to enhanced absorption and scattering.[6] Post-assembly ligand exchange strengthens interparticle coupling, enabling the emergence of whispering gallery modes that confine light along the surface of the superstructure,[7] leading to cross-talk phenomena in superstructure clusters.[8] This optical feedback triggers low-threshold lasing, with emission spectra tunable by optical[9] and dielectric[10] stimuli.

I will conclude by presenting recent advances in the formation of binary and porous nanocrystal solids,[11, 12] opening new avenues for multifunctional, reconfigurable materials. These results underscore the potential of controlled nanocrystal assembly not only for discovering new physical phenomena, but also for developing scalable, bottom-up materials for sustainable photonics and energy-efficient technologies.

[1] E. Marino, et al., Crystal Growth & Design 24 (14), 6060-6080 (2024).               
[2] R. Passante, et al., Nanoscale (in press), DOI: 10.1039/D5NR01288K (2025).  
[3] E Marino, et al., Chem. Mater. 34, 6, 2779–2789 (2022).  
[4] E. Marino, et al., Adv. Mater. 30 (43), 1803433 (2018).        
[5] E. Marino, et al., J. Phys. Chem. C 124 (20), 11256–11264 (2020).        
[6] E. Marino, et al., ACS nano 14 (10), 13806–13815 (2020).
[7] E. Marino, et al., Nano Lett. 22, 12, 4765–4773 (2022).       
[8] P. Castronovo, et al., Nano Lett. 25 (14), 5828-5835 (2025).
[9] S.J. Neuhaus, et al., Nano Lett. 23, 2, 645–651 (2023).       
[10] M. Reale et al., Adv. Opt. Mater. 34 (37), 2402079 (2024).   
[11] E. Marino, et al., Nat. Synth 3, 111–122 (2024).  
[12] E. Marino, et al., Chem. Mater. 36 (8), 3683-3696 (2024).