Nanostructured Materials for Optoelectronics and Energy Harvesting (NANOPTO)

In 2024, our group made significant advancements in several research areas. Our achievements serve as proof of our commitment to enhancing scientific understanding and developing technology with practical uses.

In Organic photovoltaics, on the one hand, we demonstrated that the implementation of the spectral splitting concept in lateral multi-junction (RAINBOW) architectures can lead to substantial increments in power conversion efficiency by minimizing absorption as well as thermalization losses. On the other hand, we used our high throughput screening methods to evaluate a number of important aspects, including the chemical structure of the acceptor, the role of the molecular weight of the donor, as well as evaluating narrow band gap materials for semitransparent and tandem cells, and wideband gap materials for indoor and multi-junction cells.

In the Photonic Architectures for Light Management research line, the work published in Advanced Materials demonstrated generation of highly anisotropic circularly polarized photoluminescence from conventional perovskite nanocrystal emitters, achieving dissymmetry emission factors of g_lum up to 0.56. The underlying chiral nanophotonic architecture was produced by scalable soft-nanoimprint lithography. Moreover, combination of dielectric and metallic chiral motifs in the architecture was shown to generate simultaneous multi-wavelength chiral emission.

Regarding the fundamental physical properties of metal halide perovskites, we published a paper on the influence of the interplay between the inorganic cage and the dynamic disorder associated to the unfolding of the A-site cation dynamics on the inorganic-cage phonon linewidths, as determined by Raman scattering.

In Thermoelectrics, we published two fundamental and broad studies with strong impact in the community. First, we introduced a novel doping strategy based on Lewis pairs that showed a very efficient and universal doping capability, and, importantly, significantly more stable than conventional methods. We also published a large study on the thermal properties of semiconducting polymers, demonstrating two regimes of correlation between thermal and electronic transport depending on the microstructure. We also published two papers on carbon nanotubes for thermoelectrics, one on the role of hidden variables (such as thickness) on stability and the other one on upscaling which describes a technology that we have patented to fabricate thick, large area CNT films.

Further knowledge transfer activities resulted in a consultancy contract established with LINSEIS GmbH, a German company recognized as a global leader in thermal analysis instrumentation, to implement advanced measurement methods for thermal analysis of materials. Additionally, these innovative methods have led to the publication of a scientific article focusing on the thermal conductivity tensor in two-dimensional materials, such as PdSe₂. This work highlights the significant potential of the developed methods for addressing thermal anisotropy in 2D materials

Highlights

• Prof. Mariano Campoy-Quiles received the Margarita Salas Medal for supervision.
• Dr. Sergi Riera-Galindo received the MAV award.
• Prof. Alejandro R. Goñi was appointed as a Plenary speaker at 109^th Annual Meeting of the Argentine Physical Society (AFA2024), presenting the work on metal halide perovskites.
• The Pathfinder Challenge project RADIANT: Chiral Light Emitting Diodes based in Photonic Architectures, coordinated by Dr. Agustín Mihi, was granted and started last November 2024.
• Dr. Juan Sebastián Reparaz signed a consultancy contract with the company LINSEIS GmbH to develop advanced tools for thermal characterization of materials.
• In 2024, three PhD students from Nanopto have successfully defended their PhD thesis:
       1) Ylli Conti, on 4^th June 2024: “Harnessing Colloidal Plasmonic Metasurfaces for Advanced Optical Phenomena”
       2) Miquel Casademont, on 24^th October 2024: "Towards organic multi-junction RAINBOW solar cells"
       3) Jiali Guo, on 30^th October 2024: "Effect of Doping and Molecular Weight on the Thermal Conductivity of Conjugated Polymers for Thermoelectrics"