Air and water sensors:
Polymer planar photonic crystals are engineered to gather the label-free detection of pollutants. These sensors are able to overcome the limitations of current technologies and to provide a tool for the assessment of air and water quality.
Label-free selectivity is achieved exploiting the different kinetics of analytes intercalation within the polymers, which is ruled by polymer-analyte chemico-physical interactions (FLORY-HUGGINS PARAMETERS). Such kinetics allow disentangling the analytes without chemical labels.
These sensors find applications in industrial and environmental monitoring and in food packaging.
Molecular diffusion in thin films:
Simple UV-Vis optical spectroscopy allows monitoring the diffusion of small molecules in polymer thin films. The kinetics of the optical response during sorption/desorption processes allows a new method for the assessment molecular diffusion coefficients in thin films by on both polymer and porous inorganic matrices. Recent work, demonstrated that the method can be applied also to commercial thin film used in food packaging systems.
Historically inorganic photonic structures have been employed for the control of light to achieve emission enhancement, lasing, optical switchers and even photon recycling in photovoltaic devices. While inorganics provides outstanding performances owing to high dielectric contrast, they require costly and time-consuming fabrications.
This research path aims to demonstrate that solution processable polymers and hybrid materials can replace inorganic media in the field. To this aim, several commercial and synthetic polymers were employed demonstrating that polymer structures are suitable for emission enhancement and lasing for inorganic nanocrystals, J-aggregates, and even perovskite emitters.
When a photoactive medium is integrated into a dielectric lattice, light absorption can be amplified within the medium itself at the stop-band edges owing to (i) light confinement and (ii) generation of slow photons propagating with reduced group velocity and thus with a longer lifetime and stronger interaction with the medium.
This topic focus on the design and fabrication of photoactive Bragg stack made of oxide semiconductors and cast via mild condition solution processing to demonstrate slow photon enhancement in water remediation and other photocatalytic processes.
Chemical processes and syntheses:
Engineering new polymeric structures often requires materials that are not available commercially. To this end, several active media are engineered and/or synthesized ad-hoc, and their processability is investigated. A large work is focused on the synthesis of inorganic nanoparticles and on their compatibilization with polymers to fabricate optical nanocomposite thin films with controllable permeability and refractive index and on the solution processing of fully-inorganic structures. Focus is also paid to hybrid polymer inorganic materials synthesized in-situ via sol-gel routes and to their compatibilization with dielectric and conjugated polymer and organic and inorganic dyes.
Light Harvesting Enhancement in Photovoltaics and Photocatalysis
Light harvesting in photoactive species can be enhanced with a variety of strategies and structures, including self-assembly scatters and diffraction systems, modification of the local density of photonic states and control of photon propagation velocity. The group has a consolidated background in the field applied to solar concentrators and is now working in photocatalytic system for air and water remediation.
Polymer and Solution processed Metamaterials
Metamaterials are artificial structures where properties are defined by the architecture rather than by composition. In general, metamaterials for photonics need downsizing at about 10 nm generating a local structure - the meta-atom - responsible for the overall properties. In this way, light-matter interactions can be controlled creating exotic effects such as negative refraction, generating hot-spots where light-matter interaction is enhanced.
Rely-photonics aims to make macromolecules active key-elements of metamaterials exploiting the ease of chemical engineering of their electronic response, which controls their refractive index, which is commonly too low for metamaterials. To this aim, the group is exploiting its consolidated background in the engineering of the optical properties of polymers to obtain proof-of-concepts elements, which are the cornerstone of modern photonics and optical signal handling, namely second harmonic generators (SHGs) and radiative rate modifier to create a new generation of more efficient and less energy consuming photonic elements.