A5048549760- Perovskite Materials and Applications
- Luminescence and Fluorescent Materials
- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- Lanthanide and Transition Metal Complexes
- Strong Light-Matter Interactions
- X-ray Diffraction in Crystallography
- Chalcogenide Semiconductor Thin Films
- Crystallization and Solubility Studies
- Quantum and electron transport phenomena
- Luminescence Properties of Advanced Materials
- Magnetism in coordination complexes
- Photonic and Optical Devices
- Organic Electronics and Photovoltaics
- Random lasers and scattering media
- Semiconductor Lasers and Optical Devices
- 2D Materials and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Solid-state spectroscopy and crystallography
- Quantum optics and atomic interactions
- Plasmonic and Surface Plasmon Research
- Conducting polymers and applications
- Metal-Organic Frameworks: Synthesis and Applications
- Photonic Crystals and Applications
- Molecular Junctions and Nanostructures
University of Cagliari
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari
2014-2024
National Interuniversity Consortium of Materials Science and Technology
2018-2024
Northwestern University
2023
University of Milano-Bicocca
2008
École Polytechnique Fédérale de Lausanne
1996-2005
Istituto Nazionale per la Fisica della Materia
2004-2005
Alcatel Lucent (Germany)
2002-2003
École Polytechnique
2000
The two-photon absorption coefficient and Kerr of bulk crystalline silicon are determined near the telecommunication wavelengths 1.3 1.55 μm using femtosecond pulses a balanced Z-scan technique. A phase shift sensitivity order 1 mrad is achieved, enabling accurate measurement third-order nonlinear coefficients at fluences smaller than 100 μJ/cm2. From (β∼0.8 cm/GW) (n2∼4×10−14 cm2/W) wavelength λ=1.54 μm, value F∼0.35 for figure merit all-optical switching determined.
Abstract Metal-halide perovskite solar cells rival the best inorganic in power conversion efficiency, providing outlook for efficient, cheap devices. In order technology to mature and approach ideal Shockley-Queissier experimental tools are needed diagnose what processes limit performances, beyond simply measuring electrical characteristics often affected by parasitic effects difficult interpret. Here we study microscopic origin of recombination currents causing photoconversion losses with...
ConspectusMetal halide perovskites have come to the attention of scientific community for progress achieved in solar light conversion. Energy sustainability is one priorities our society, and materials advancements resulting low-cost but efficient cells large-area lighting devices represent a major goal applied research. From basic point view, are an exotic class hybrid combining some merits organic inorganic semiconductors: large optical absorption, mobilities, tunable band gap together...
Advances of optoelectronic devices based on methylammonium lead halide perovskites depend understanding the role excitons, whether it is marginal as in inorganic semiconductors, or crucial, like organics. However, a consensus exciton binding energy and its temperature dependence still lacking, even for widely studied iodide bromide materials (MAPbI3, MAPbBr3). Here we determine an f-sum rule integrated UV–vis absorption spectra, circumventing pitfalls least-squares fitting procedures. In...
Excitons in lead halide perovskites often go unnoticed as minority species, yet they account for almost all of light emission.
Layered 2D perovskites are making inroads as materials for photovoltaics and light emitting diodes, but their photophysics is still lively debated. Although large exciton binding energies should hinder charge separation, significant evidence has been uncovered an abundance of free carriers among optical excitations. Several explanations have proposed, like dissociation at grain boundaries or polaron formation, without clarifying yet if excitons form then dissociate, the formation prevented...
This work challenges the conventional approach of using NdIII 4F3/2 lifetime changes for evaluating experimental → YbIII energy transfer rate and efficiency. Using near-infrared (NIR) emitting Nd:Yb mixed-metal coordination polymers (CPs), synthesized via solvent-free thermal grinding, we demonstrate that [2H11/2 4I15/2] [2F7/2 2F5/2] pathway, previously overlooked, dominates due to superior resonance J-level selection rule compatibility. finding upends focus on [4F3/2 4I11/2] transition...
Nanocrystal/fullerene derivative inorganic–organic hybrid photodetectors exhibiting high detectivity for near-IR wavelengths and a linear power dependence are produced. The ultrafast electron transfer from the PbS crystals to fullerene opens new route obtaining efficient that appealing, cost-effective alternatives currently available technology.
We study gain and lasing processes in individual self-assembled organic nanofibers grown on mica substrates. The gain-induced response of the is found to depend sensitively fiber structure. In homogeneous fibers where no coherent optical feedback present, high net (of up 103cm−1) results spectral narrowing at material peaks. case strong feedback, which occurs long with randomly distributed scattering centers, turn responsible for low-threshold random laser action.
Amplified spontaneous emission in methylammonium lead halide perovskites over transients as long 100 ns at 200 K temperature is demonstrated. Optical spectroscopy measurements highlight runaway heating dynamics limiting the duration of optical amplification, but also suggest materials and device improvements to circumvent such limitations allow true continuous wave operation. As a service our authors readers, this journal provides supporting information supplied by authors. Such are peer...
Among solution‐processed nanocrystals containing environmentally benign elements, bismuth sulfide (Bi 2 S 3 ) is a very promising n‐type semiconductor for solar energy conversion. Despite the prompt success in fabrication of optoelectronic devices deploying Bi nanocrystals, limited understanding electronic properties represents hurdle further materials developments. Here, two key science issues light‐energy conversion are addressed: bandgap tunability via quantum size effect, and...
Abstract Hybrid lead halide perovskites are unique solution‐processed semiconductors with very large optical absorption coefficients in the visible spectrum, diffusion length of photoexcited charge carriers, and long excited state lifetimes, properties that have been exploited for realization solar cells LEDs. However, one most fundamental hybrid perovskites, whether bandgap is direct or indirect, actively debated. While considered published literature, recent studies proposed Rashba...
Abstract Surface properties are often assessed with measurements of the contact angle a water drop. The process is however flawed for very important class hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they soluble their surface degrades during measurements. While perovskites considered to be highly hydrophilic, 83° can measured, as if were almost hydrophobic. By combining experiments simulations, actual value explained result...
Tuning of luminescent and SIM properties is herein reported, in a novel flexible 3D anilato-based Er III -MOF, displaying reversible shrinkage/expansion from distorted hexagonal to 3,6-brickwall rectangular structure.
We report on the observation of amplified spontaneous emission and random lasing in self-organized crystalline para-sexiphenyl nanofibers. Using subpicosecond excitation, a threshold is observed 0–1 band near 425 nm at excitation fluences as low 0.5 μJ/cm2 (6×1016 cm−3 equivalent density), onset density-dependent recombination processes. The dependence nonlinear spectrum both pump intensity position area are attributed to interplay between occurring along
Exciton-exciton interaction in dot/rod CdSe/CdS nanocrystals has proved to be very sensitive the shape of nanocrystals, due unique band alignment between CdSe and CdS. Repulsive exciton-exciton is demonstrated, which makes dot/rods promising gain media for solution-processable lasers, with projected pump threshold densities below 1 kW cm(-2) continuous wave lasing.
Abstract All‐organic nanostructured host–guest materials (see picture) show enhanced, tunable fluorescence due to a high concentration of dyes with controlled spatial and geometrical organization that allows resonant energy transfer. Homogeneous films deoxycholic acid host–guests, provide coatings convert near‐UV light into blue an efficiency higher than the standard polymeric blends. magnified image systems, based on inserted in nanochannels perhydrotriphenylene (PHTP) (DCA), enhanced...
One-dimensional light amplification in individual p-sexiphenyl nanofibers is investigated. The influence of fiber morphology on propagation properties studied via optical and atomic force microscopy. Isolated are shown to yield low-threshold random laser emission the deep blue. Model calculations coherent one-dimensional media qualitatively reproduce experimental results. Implications for photonic nanosensors briefly discussed.
We report the first combined optical and structural investigation of water free Er-quinolinolate complex, an organo-lanthanide system interest for 1.5-microm telecom applications. Structural data demonstrate that complex has a trinuclear structure (Er3Q9) which provides Er metals with octa-coordination by organic ligand prevents solvent molecules from entering lanthanide coordination sphere. The results analysis allow us to infer strong luminescence quenching exhibited Er3Q9 is due uniquely...
We investigate the quenching of near infrared light emission in Er3+ complexes induced by resonant dipolar interaction between rare-earth ion and high frequency vibrations organic ligand. The nonradiative decay rate lanthanide is discussed terms a continuous medium approximation, which depends only on few, easily accessible spectroscopic structural data. model accounts well for available experimental results complexes, predicts an ∼100% quantum yield fully halogenated systems.
Abstract Erbium quinolinolates, commonly assumed to be mononuclear species with octahedral co‐ordination geometry, have been proposed as promising materials for photonic devices but difficulties in obtaining well defined products so far limited their use. We report here the conditions obtain high yields three different kinds of pure neutral erbium quinolinolates by mixing an salt 8‐quinolinol (HQ) and 5,7‐dihalo‐8‐quinolinol (H5,7XQ: X = Cl Br): i) trinuclear complex Er 3 Q 9 ( 1 ) which is...
We investigate a promising organic/inorganic hybrid composite for solution-processable optoelectronics made by lead sulphide nanoparticles and fullerene derivatives, which combine the sensitivity of PbS to infrared spectrum with good electron transport properties fullerenes. Charge separation is crucial process that determines whether heterojunction can be building block devices converting photogenerated excitons into free charges flowing in circuit. Subpicosecond spectroscopy techniques on...
The synthesis, structural characterization, photophysical studies, and exfoliation of two-dimensional (2D) layered coordination polymers, formulated as {[Ln2(ClCNAn)3(DMF)6]·(DCM)x}n (Ln(III) = Yb(x 0), Nd, Er (x 2)) based on the heterosubstituted chlorocyananilate ligand, are reported. These compounds consist neutral polymeric 2D networks ligand alternating with Ln(III) ions. They form six-membered rings rectangular cavities, where neighbor layers eclipsed along a axis (Yb), regular...
Abstract Understanding exciton formation is of fundamental importance for emerging optoelectronic materials, like hybrid organic–inorganic perovskites, as excitons are the lowest‐energy photoexcitations in semiconductors, electrically neutral, and do not directly contribute to charge transport, but can emit light more efficiently than free carriers. However, despite increasing attention toward these experimental results on processes an population perovskites still elusive. Here, ultrafast...