A5045944338- Perovskite Materials and Applications
- Strong Light-Matter Interactions
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Cold Atom Physics and Bose-Einstein Condensates
- Semiconductor Quantum Structures and Devices
- Luminescence and Fluorescent Materials
- Quantum and electron transport phenomena
- Lanthanide and Transition Metal Complexes
- Advanced Photocatalysis Techniques
- Solid-state spectroscopy and crystallography
- Crystallization and Solubility Studies
- Organic Electronics and Photovoltaics
- X-ray Diffraction in Crystallography
- Conducting polymers and applications
- Luminescence Properties of Advanced Materials
- Plasmonic and Surface Plasmon Research
- Thermal Radiation and Cooling Technologies
- Gold and Silver Nanoparticles Synthesis and Applications
- 2D Materials and Applications
- Quantum Information and Cryptography
- Magnetism in coordination complexes
- Quantum, superfluid, helium dynamics
- Molecular Junctions and Nanostructures
- Photonic and Optical Devices
University of Cagliari
2016-2025
Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari
2013-2024
University of Perugia
2023
Northwestern University
2023
Istituto Officina dei Materiali
2015
MIT-Harvard Center for Ultracold Atoms
2003-2007
Massachusetts Institute of Technology
2003-2007
École Polytechnique Fédérale de Lausanne
1999-2005
Harvard University
2004
École Polytechnique
2000
A trapped-atom interferometer was demonstrated using gaseous Bose-Einstein condensates coherently split by deforming an optical single-well potential into a double-well potential. The relative phase between the two determined from spatial of matter wave interference pattern formed upon releasing separated wells. Coherent evolution observed for held 13 microm up to 5 ms and controlled applying ac Stark shift potentials either condensates.
We measured the relative phase of two Bose-Einstein condensates confined in an radio frequency induced double well potential on atom chip. observed coherence between separated for times up to 200 ms after splitting, a factor 10 beyond diffusion limit expected coherent state our experimental conditions (20 ms). The enhanced time is attributed number squeezing initial by 10. In addition, we demonstrated rotationally sensitive (Sagnac) geometry guided interferometer propagating split condensates.
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...
We observed quantum reflection of ultracold atoms from the attractive potential a solid surface. Extremely dilute Bose-Einstein condensates ^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in weak gravito-magnetic trap were normally incident on silicon Reflection probabilities up to 20 % for velocities 1-8 mm/s. The velocity dependence agrees qualitatively prediction Casimir-Polder potential. Atoms harmonic divided half by surface exhibited extended lifetime due surface,...
Doubly quantized vortices were topologically imprinted in /F=1> 23Na condensates, and their time evolution was observed using a tomographic imaging technique. The decay into two singly characterized attributed to dynamical instability. scale of the splitting process found be longer at higher atom density.
Spin-polarized gaseous Bose-Einstein condensates were confined by a combination of gravitational and magnetic forces. The partially condensed atomic vapors adiabatically decompressed weakening the gravito-magnetic trap to mean frequency 1hertz, then evaporatively reduced in size 2500 atoms. This lowered peak condensate density 5 x 10(10) atoms per cubic centimeter cooled entire cloud all three dimensions kinetic temperature 450 +/- 80 picokelvin. Such spin-polarized, dilute, ultracold gases...
We study how interactions affect the quantum reflection of Bose-Einstein condensates. A patterned silicon surface with a square array pillars resulted in high probabilities. For incident velocities greater than 2.5 mm/s, our observations agreed single-particle theory. At below measured probability saturated near 60% rather increasing towards unity as predicted by accepted theoretical model. extend theory to account for mean-field condensate which suppresses at low velocity. The reflected...
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.
Abstract The rational design of heterojunctions based on metal halide perovskites (MHPs) is an effective route to create novel photocatalysts run relevant solar‐driven reactions. In this work, experimental and computational study the synergic coupling between a lead‐free Cs 3 Bi 2 Br 9 perovskite derivative g‐C N 4 presented. A boost hydrogen photogeneration by more than one order magnitude recorded when going from pure /g‐C system. Effective catalytic activity also achieved in degradation...
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...
Inorganic metal halide perovskites such as CsPbI3 are promising for high-performance, reproducible, and robust solar cells. However, inorganic sensitive to humidity, which causes the transformation from black phase yellow δ, non-perovskite phase. Such instability has been a significant challenge long-term operational stability. Here, surface dimensionality reduction strategy is reported, using 2-(4-aminophenyl)ethylamine cation construct Dion-Jacobson 2D that covers of 3D perovskite...
We have used a microfabricated atom chip to split single Bose-Einstein condensate of sodium atoms into two spatially separated condensates. Dynamical splitting was achieved by deforming the trap along tightly confining direction purely magnetic double-well potential. observed matter wave interference pattern formed upon releasing condensates from microtraps. The intrinsic features quartic potential at merge point, such as zero frequency and extremely high field-sensitivity, caused random...
We demonstrated an experimental technique based on stimulated light scattering to continuously sample the relative phase of two spatially separated Bose-Einstein condensates atoms. The measurement process created a between with no initial relation, read out phase, and monitored evolution. This was used realize interferometry trapped without need for splitting or recombining atom cloud.
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.
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...
Chemical potential<italic>μ</italic><sub>eh</sub>and radiative lifetime<italic>τ</italic><sub>rad</sub>behaviour<italic>vs.</italic>carrier density<italic>n</italic>in FASnI<sub>3</sub>. They change dramatically with hole doping concentration, inducing large Burstein–Moss shift
There is increasing interest in the role of metal halide perovskites for heterogeneous catalysis. Here, we report a Ge-based 2D perovskite material that shows intrinsic water stability realized through organic cation engineering. Incorporating 4-phenylbenzilammonium (PhBz) demonstrate, by means extended experimental and computational results, PhBz2GeBr4 PhBz2GeI4 can achieve relevant air stability. The creation composites embedding graphitic carbon nitride (g-C3N4) allows proof concept...
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.