Hugo A. Lara-García

Fully solution-processed Bragg mirrors with high reflectance support strong light–matter coupling at room temperature, providing a scalable platform for perovskite polaritonic devices.

Distinguished by their long lifetimes, strong dipolar interactions, and periodic confinement, moiré excitons are fertile ground for realising interaction-driven excitonic phases beyond conventional semiconductor systems. Formed in twisted or lattice-mismatched van der Waals heterostructures, these excitons are shaped by a periodic potential landscape that enables the engineering of flat bands, strong interactions, and long-lived localised states. This has opened pathways to explore strongly correlated phases, including excitonic insulators, superfluids, and supersolids, potentially stable even at room temperature. When embedded in optical cavities, moiré excitons hybridise with photons to form moiré exciton–polaritons, a new class of quasiparticles exhibiting enhanced optical nonlinearities and novel topological features. In this review, we survey the theoretical foundations and experimental progress in the field of moiré excitons and polaritons. We begin by introducing the formation mechanisms of moiré patterns in two-dimensional semiconductors, and describe their impact on exciton confinement, optical selection rules, and spin-valley physics. We then discuss recent advances in the realisation of many-body excitonic phases and exciton-based probes of electronic correlations. Finally, we explore the novel aspects of moiré polaritons, highlighting their unique nonlinear and topological properties. By bridging quantum optics, nanophotonics, and correlated electron systems, moiré excitons offer a powerful solid-state platform for quantum simulation, optoelectronic applications, and many-body photonics.

Growing environmental concerns and the persistence of organic pollutants underscore the urgent need for effective wastewater treatment. Among the various strategies developed to address this challenge, photocatalysis has emerged as a promising approach due to its potential for sustainable and efficient degradation of pollutants. In this study, we investigate the simultaneous incorporation of transition metal cations (Cu ² ⁺, Ni ² ⁺, Co ² ⁺, and Fe ³ ⁺) into the crystalline structure of titanate nanotubes (H₂Ti₃O₇, TiNT) via a straightforward ion-exchange method. This modification promotes the formation of a p-n heterostructure between TiNT and the corresponding metal oxides (CuO, NiO, CoO, and Fe₂O₃). Remarkably, metal cation incorporation leads to a substantial reduction in the band gap, from 3.3 eV to 1.5 eV, and induces a new absorption feature associated with the formation of p-n heterojunctions. These modifications effectively extend the light absorption of the materials into the visible region. Furthermore, the formation of the p-n heterojunction increased charge carrier density compared to that obtained in pristine TiNT. The photocatalytic activity of the resulting metal-doped TiNT (M-TiNT) semiconductors was evaluated for the degradation of ibuprofen and indigo carmine under both UV and visible light irradiation. The enhanced photocatalytic performance is attributed to improved light harvesting and increased availability of charge carriers, facilitating the generation of reactive redox species. The importance of the hydroxyl radical as a reactive species was confirmed using a hydroxyl radical scavenger, which led to a significant reduction in photocatalytic activity compared to the control experiment without the scavenger. Notably, Cu–TiNT remained stable after the reuse cycles, retaining 90% of its initial photoactivity. These findings provide valuable insights for the rational design of nanostructured photocatalysts and underscore the potential of metal-doped TiNTs for efficient environmental remediation.

A new, facile, and scalable ultrasound-assisted synthesis yields Cs ₂ AgBiBr ₆ nanocrystals (∼6 nm) with high visible-light photocatalytic activity and remarkable stability.

Exciton-polariton Bose-Einstein condensation at room temperature offers a promising pathway toward quantum photonic technologies that can operate under ambient conditions. A key challenge in this field is to engineer a controlled platform where strong confinement, nonlinear interactions, and structural disorder coexist, unlocking access to rich collective behavior and unconventional condensate dynamics. We demonstrate polariton condensation in CsPbBr$_3$ microplatelets that self-assemble into whispering gallery mode microresonators featuring tight lateral photon confinement finely balanced with intrinsic disorder. The system exhibits hallmark signatures of out-of-equilibrium condensation, including a non-linear increase in emission intensity, spectral narrowing, and interaction-induced blueshift. Intrinsic disorder subtly reshapes the cavity energy landscape, inducing condensate fragmentation and enabling direct optical access to the condensate wavefunction. Interferometric measurements reveal extended phase coherence, whereas characteristic fork-shaped fringe dislocations confirm the presence of quantized vortices pinned by the disordered potential. These topological excitations underscore the rich physics driven by the interplay of gain, loss, confinement, and disorder. Our work establishes a scalable platform for investigating driven-dissipative quantum fluids of light at room temperature, where the intrinsic disorder balances optical confinement and provides a window into condensate wavefunction, coherence, and vortex phenomena. This study system opens new opportunities for exploring many-body physics and potentially advancing topological photonics in integrable microcavity architectures.

Band engineering stands as an efficient route to induce strongly correlated quantum many-body phenomena. Besides inspiring analogies among diverse physical fields, tuning on demand the group velocity is highly attractive in photonics because it allows unconventional flows of light. Λ-schemes offer a route to control the propagation of light in a lattice-free configurations, enabling exotic phases such as slow-light and allowing for highly optical non-linear systems. Here, we realize room-temperature intercavity Frenkel polaritons excited across two strongly coupled cavities. We demonstrate the formation of a tuneable heavy-polariton, akin to slow light, appearing in the absence of a periodic in-plane potential. Our photonic architecture based on a simple three-level scheme enables the unique spatial segregation of photons and excitons in different cavities and maintains a balanced degree of mixing between them. This unveils a dynamical competition between many-body scattering processes and the underlying polariton nature which leads to an increased fluorescence lifetime. The intercavity polariton features are further revealed under appropriate resonant pumping, where we observe suppression of the polariton fluorescence intensity.

The influence of Ni(ii) coordinatively unsaturated metal sites and coordinated water on the SO₂ adsorption performance of NiBDP were investigated.