Adele Sassella

Thanks to the commercial success of organic light-emitting diodes, organic electronics is now much more than just a niche alternative to traditional electronics. However, other types of devices based on organic semiconductors (OSCs) are still far from market readiness. A key limitation is that, in thin-film form, OSCs exhibit a high level of structural disorder. Of all strategies for growing films of OSCs, those relying on organic epitaxy yield films whose properties most closely resemble those of single crystals. Yet, this comes at a cost: conventional substrates for epitaxial growth are incompatible with practical device integration. To overcome this issue, we introduce a transfer printing method capable of relocating epitaxially grown films of OSCs from their native substrates to target, device-compatible ones. We demonstrate the feasibility of this approach by transferring highly crystalline rubrene films─grown via organic molecular beam epitaxy and characterized by coherently oriented, micrometer-scale domains and single-crystal-like optical response─from amino acid single crystals to technologically relevant substrates. Notably, morphology, optical characteristics, and photoluminescence dynamics of the films are fully retained following transfer.

The results obtained using laboratory and transportable XRF and RS instruments to analyze metal ingots discovered from a Roman shipwreck are compared to assessing the possibility of in situ analyses.

Cu ₂ ZnSnS ₄ nanoparticles as hole transport material stabilise perovskite solar cells' performance.

Starch-cinnamyl ethers are synthesized, shaped into thin films and characterized for their ability to undergo photo crosslinking.

Insights for an effective evaluation of copper exsolution in Cu-doped SrTiO ₃ have been obtained by combining classical techniques with EPR.

Crystalline rubrene (RUB) in the orthorhombic structure can be regarded as a workhorse in organic optoelectronics. So far, however, its great potential for device integration has been held back by the struggle to obtain high quality and photo-oxidation resistant RUB thin films. Here, we propose an effective strategy to obtain homogeneous, highly crystalline, and oriented RUB thin films, which relies on a spontaneous amorphous-to-crystal transition driven by organic epitaxy occurring at room temperature in vacuum: this crucial process dictates the final morphological, structural, and optoelectronic properties of the film. To probe the kinetics of the transition, we combine an ex-situ analysis via polarized optical spectroscopy and atomic force microscopy with a photoluminescence investigation carried out in-situ, based on monitoring the efficiency of the singlet fission process typical of crystalline RUB. Building on the insights gained, we tune the thin film growth and post-growth parameters, so as to obtain centimeter-scale, highly homogeneous and crystalline RUB thin films, constituted by several μm-sized and coherently oriented domains, featuring oxidation resistance.

The ability to control the properties of organic thin films is crucial for obtaining highly performant thin-film devices. However, thin films may experience post-growth processes, even when the most sophisticated and controlled growth techniques such as organic molecular beam epitaxy (OMBE) are used. Such processes can modify the film structure and morphology and, thus, the film properties ultimately affecting device performances. For this reason, probing the occurrence of post-growth evolution is essential. Equally importantly, the processes responsible for this evolution should be addressed in view of finding a strategy to control and, possibly, leverage them for driving film properties. Here, nickel-tetraphenylporphyrin (NiTPP) thin films grown by OMBE on highly oriented pyrolytic graphite (HOPG) are selected as an exemplary system exhibiting a remarkable post-growth morphology evolution consistent with Ostwald-like ripening. To quantitatively describe the growth, the height-height correlation function (HHCF) analysis of the atomic force microscopy (AFM) images is carried out, clarifying the role of the post-growth evolution as an integral part of the whole growth process. The set of scaling exponents obtained confirms that the growth is mainly driven by diffusion combined with the presence of step-edge barriers, in agreement with the observed ripening phenomenon. Finally, the results together with the overall approach adopted demonstrate the reliability of the HHCF analysis in systems displaying post-growth evolution.