Istituto Italiano di Tecnologia

About: Istituto Italiano di Tecnologia is a facility organization based out in Genoa, Italy. It is known for research contribution in the topics: Robot & Humanoid robot. The organization has 4561 authors who have published 14595 publications receiving 437558 citations. The organization is also known as: Italian Institute of Technology & IIT.

Dynamical Origin of the Rashba Effect in Organohalide Lead Perovskites: A Key to Suppressed Carrier Recombination in Perovskite Solar Cells?

Abstract: The presence of a Rashba band-splitting mechanism mediated by spin–orbit coupling and breaking of inversion symmetry has been suggested as a possible cause for the reduced recombination rates observed in organohalide perovskites. Here, we investigate the interplay of electronic and nuclear degrees of freedom in defining the Rashba splitting in realistic MAPbI3 models. Our simulations disclose a “dynamical Rashba effect”, allowing for a quantification of its magnitude under thermal conditions. We find that even in globally centrosymmetric structures the dynamics of the coupled inorganic–organic degrees of freedom give rise to a spatially local Rashba effect which fluctuates on the subpicosecond time scale typical of the methylammonium cation dynamics. This effect is progressively quenched in globally centrosymmetric structures, likely representing the MAPbI3 perovskite at room temperature, on increasing the probed spatial scale up to 32 MAPbI3 units (∼3 nm size) because of the incoherent nuclear thermal mo...

Superballistic flow of viscous electron fluid through graphene constrictions

Abstract: Graphene systems are clean platforms for studying electron–electron (e–e) collisions. Electron transport in graphene constrictions is now found to behave anomalously due to e–e interactions: conductance values exceed the maximum free-electron value. Electron–electron (e–e) collisions can impact transport in a variety of surprising and sometimes counterintuitive ways1,2,3,4,5,6. Despite strong interest, experiments on the subject proved challenging because of the simultaneous presence of different scattering mechanisms that suppress or obscure consequences of e–e scattering7,8,9,10,11. Only recently, sufficiently clean electron systems with transport dominated by e–e collisions have become available, showing behaviour characteristic of highly viscous fluids12,13,14. Here we study electron transport through graphene constrictions and show that their conductance below 150 K increases with increasing temperature, in stark contrast to the metallic character of doped graphene15. Notably, the measured conductance exceeds the maximum conductance possible for free electrons16,17. This anomalous behaviour is attributed to collective movement of interacting electrons, which ‘shields’ individual carriers from momentum loss at sample boundaries18,19. The measurements allow us to identify the conductance contribution arising due to electron viscosity and determine its temperature dependence. Besides fundamental interest, our work shows that viscous effects can facilitate high-mobility transport at elevated temperatures, a potentially useful behaviour for designing graphene-based devices.

Symmetric dimethylation of H3R2 is a newly identified histone mark that supports euchromatin maintenance

Abstract: The asymmetric dimethylation of histone H3 arginine 2 (H3R2me2a) acts as a repressive mark that antagonizes trimethylation of H3 lysine 4. Here we report that H3R2 is also symmetrically dimethylated (H3R2me2s) by PRMT5 and PRMT7 and present in euchromatic regions. Profiling of H3-tail interactors by SILAC MS revealed that H3R2me2s excludes binding of RBBP7, a central component of co-repressor complexes Sin3a, NURD and PRC2. Conversely H3R2me2s enhances binding of WDR5, a common component of the coactivator complexes MLL, SET1A, SET1B, NLS1 and ATAC. The interaction of histone H3 with WDR5 distinguishes H3R2me2s from H3R2me2a, which impedes the recruitment of WDR5 to chromatin. The crystallographic structure of WDR5 and the H3R2me2s peptide elucidates the molecular determinants of this high affinity interaction. Our findings identify H3R2me2s as a previously unknown mark that keeps genes poised in euchromatin for transcriptional activation upon cell-cycle withdrawal and differentiation in human cells.

Fluorescent Alloy CsPbxMn1–xI3 Perovskite Nanocrystals with High Structural and Optical Stability

Abstract: CsPbI3 nanocrystals are still limited in their use because of their phase instability as they degrade into the yellow nonemitting δ-CsPbI3 phase within a few days. We show that alloyed CsPbxMn1–xI3 nanocrystals have essentially the same optical features and crystal structure as the parent α-CsPbI3 system, but they are stable in films and in solution for periods over a month. The stabilization stems from a small decrease in the lattice parameters slightly increasing the Goldsmith tolerance factor, combined with an increase in the cohesive energy. Finally, hybrid density functional calculations confirm that the Mn2+ levels fall within the conduction band, thus not strongly altering the optical properties.