In organic photovoltaics (PV), the high-throughput experimental screening and characterization approach based on lateral parametric gradients (measuring-intensive) developed at ICMAB has been combined with machine-learning algorithms to retrieve quantitative structure–activity relationships and extract molecular design rationale, accelerating organic solar-cell material discovery. Regarding complex oxides for PV applications like of BiFeO3, its phase stability and optoelectronic performance was enhanced and a cost-effective route to prepare freestanding complex oxide films was developed. Concerning hybrid lead halide perovskites, the first systematic assignment of common features apparent in the low-temperature PL spectra of single crystals to shallow defects was performed.

A combined strategy based on light trapping in 2D photonic crystals and plasmonic resonances has been successfully implemented for hydrogen production by photo-catalysis in the visible. Furthermore, it has been shown that redox gradients generated by wireless electrochemical processes, for example, in electro-deposited iridium oxide strongly enhance O2 evolution kinetics with applications in electro-catalysis and neural growth.

Regarding thermal transport, the recent experimental observation of “second sound” in bulk Ge even at room temperature and its modeling and simulation using nonequilibrium molecular dynamics open a new research field of wave-like heat transport, potentially, in almost any material. Further advances in general theory involve the development of workflow interfaces that automatically compute material properties and the derivation of a dielectric-screening theory in quasi-2D materials.

Batteries based on multivalent ions (e.g. Ca2+, Mg2+) and metal anodes could enable very high energy densities, thus, activities within 2021 included the screening of new materials as potential cathodes for Ca metal batteries using operando techniques and the development of boron-containing electrolyte additives. Carbons derived from alcohol-treated bacterial cellulose with optimal porosity were obtained, showing excellent behavior for Li-O2 Batteries.

New hybrid nanocarbon-metal oxide electrodes were developed for supercapacitors using innovative laser-based electrode fabrication methods, which were further up-scaled to meet industrial standards.

Highly flexible 3D porous metal–organic frameworks (MOFs) were modified to incorporate conducting polypyrrole, so as to enhance their stability and capacitance as electrode material. Nanocomposite aerogels made of MOFs and graphene oxide have been developed for efficient CO2 and CH4 adsorption and separation.

The research line has progressed in the understanding of the ferroelectric phase of epitaxial HfO₂ thin films, a key material in the spotlight of the memories industry. Researchers of the RL exploit this knowledge to engineer ultrathin tunnel barriers for memory applications and neuromorphic applications.

Polar materials are also investigated in the context of flexoelectricity and the interaction with light. In this regard, flexoelectric responses of two-dimensional materials has been fully calculated from first principles, of interest for applications to graphene, silicene, phosphorene, boron nitride, and transition-metal dichalcogenide monolayers. Along these lines, switching of polar metals via strain gradients have been also studied via first-principles theory. On the other hand, the photoresponse of polar oxides has been exploited to control ferroelectric memories, showing that the photocurrent can be reversed via polarization switching.

RL3 researchers have also demonstrated the role of relative humidity and polarization switching history on the surface charge dissipation in ferroelectric Pb(Zr0.2Ti0.8)O3 thin films. Other discoveries relate to the finding of a metallic monoclinic VO2 phase that bridges the metallic rutile and insulating monoclinic ground states, promoting the formation of tweed microstructures. On the other hand, indium-free metallic electrodes based on SrVO₃ have led to the discovery that the effective electron-mass enhancement, responsible for its transparency at visible range, is due to electron-phonon coupling rather than electron-electron correlations, as commonly accepted.

Potential high-temperature multiferroics have been investigated based on YBaCuFeO5 multiferroics: the modulation of spiral planes and Fe/Cu cation disorder has been exhaustively determined, which is crucial to engineer and develop these materials towards high-temperature multiferroics.

Finally, spintronic activities have been reinforced by the incorporation of an ERC grantee, who has been awarded by 2021 IUPAP Young Scientist Prize in the field of Magnetism, in recognition for the outstanding contributions in the field of magnetic oxides for spintronics.

RL5 generated scientific and technological knowledge on the synthesis and processing  of new materials of interest to biomedical companies and clinical groups for improved diagnosis and treatment of diseases by increasing  the selectivity, efficiency and safety of the nanomedicinal system. RL5 has contributed in its three research areas:

1. Materials engineering and biointeraction: developing boron clusters, curcuminoids, nanoparticles (i.e. polymeric, inorganic, hybrid, liposomes or vesicles) and biofunctionalized surfaces (i.e. electrode coatings with electroactive conducting materials or self-assembled monolayers to control material-cell interaction and 3D scaffolds (i.e. synthetic and biobased hydrogels) targeting specific properties.
2. Therapy; generating new effective materials targeting specific functions to find solutions in different illnesses. Developing new boron clusters-based hybrid materials as anticancer agents for BNCT and for multimodal cancer therapies, design carbon and inorganic nanomaterials as theranostic agents for biomedical imaging (fluorescent dyes, radionuclides, or contrast agents for MR) and cancer therapy and hydrogels to improve adoptive cell therapy to efficiently culture immune cells. Also, developing synthetic and biobased nanocellulose hydrogels for corneal or myocardial tissue repair and as cell support nanoconstructs, electroactive hybrid materials for neural repair, PLGA nanocapsules to enhance brain vascularization, quatsomes for the delivery of EGF for ulcer treatment (pushed to TRL7), carbon nanotubes and hybrid composites (protein nanoparticles functionalized PLA scaffold).
3. Bioimaging: developing fluorescent dyes based on small organic molecules and nanoparticles and vesicles that are internalized by cells as fluorescent probes, radical dendrimers to substitute gadolinium for MRI for in-vivo applications. Iron oxide nanoparticles as T2 contrast agent combined with other carriers, such as mesoporous silica particles, PLGA capsules or carbon-based materials to increase image quality and clinical sensitivity and new molecules and nanoparticles functionalized with radioisotopes for their applications in PET-SPECT imaging.

RL5 participated defining the challenges of nanomedicine in the coming decade in line with the scientific and technological guidelines of the CSIC, contributing to the published “White Book of CSIC 2030”