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Herein, we explore, from a theoretical perspective, the nonradiative photoinduced processes (charge separation and energy transfer) within a family of donor–acceptor supramolecular complexes based on the electron-donor truxene-tetrathiafulvalene (truxTTF) derivative and a series of curved fullerene fragments (buckybowls) of different shapes and sizes (C30H12, C32H12, and C38H14) as electron acceptors that successfully combine with truxTTF via non-covalent interactions. The resulting supramolecular complexes (truxTTF·C30H12, truxTTF·C32H12, and truxTTF·C38H14) undergo charge-separation processes upon photoexcitation through charge-transfer states involving the donor and acceptor units. Despite the not so different size of the buckybowls, they present noticeable differences in the charge-separation efficiency owing to a complex decay post-photoexcitation mechanism involving several low-lying excited states of different natures (local and charge-transfer excitations), all closely spaced in energy. In this intricate scenario, we have adopted a theoretical approach combining electronic structure calculations at (time-dependent) density functional theory, a multistate multifragment diabatization method, the Marcus–Levitch–Jortner semiclassical rate expression, and a kinetic model to estimate the charge separation rate constants of the supramolecular heterodimers. Our outcomes highlight that the efficiency of the photoinduced charge-separation process increases with the extension of the buckybowl backbone. The supramolecular heterodimer with the largest buckybowl (truxTTF·C38H14) displays multiple and efficient electron-transfer pathways, providing a global photoinduced charge separation in the ultrafast time scale in line with the experimental findings. The study reported indicates that modifications in the shape and size of buckybowl systems can give rise to attractive novel acceptors for potential photovoltaic applications. [ABSTRACT FROM AUTHOR]

Core design is the a priori study of the behavior of a reactor core throughout a cycle between two fuel reloads. There is a growing interest in using Artificial Intelligence (AI) tools to accelerate this type of calculation. Coupled thermal-hydraulic/neutronic calculations allow access to many variables of special interest to develop a digital twin (metamodel), which can be used, for instance, for pattern optimization, since it presents restrictions from the point of economics, safety and licensing. This work presents a neural network (NN) trained to obtain a metamodel, which will be used to determine different optimal configurations of the fuel elements based on certain criteria.

A comprehensive investigation of two new molecular triads incorporating the diketopyrrolopyrrole unit into a quinoidized thienothiophene skeleton, which is further end‐capped with dicyanomethylene (DPP‐TT‐CN) or phenoxyl groups (DPP‐TT‐PhO), has been carried out. A combination of UV‐Vis‐NIR and infrared spectroelectrochemical techniques and cryogenic UV‐Vis‐NIR absorption spectroscopy supported by theoretical calculations has been used. The main result is the formation of similar H‐aggregates in the dimerization process of the neutral molecules and of the charged anionic species. The experimental absorption spectra of the aggregated species are accurately reproduced by quantum chemical calculations using the Spano's model, including excitonic coupling for the dimeric forms and full vibronic resolution of the absorption bands. The strong excitonic coupling taking place is key to understand the electronic structure of the dimeric species and has been instrumental to disentangle the type of H‐aggregation. This study is of relevance to get a better understanding of the molecular aggregation of organic π‐conjugated chromophores and is useful as a guideline for the refinement of the engineering of molecular materials for which supramolecular design is required. [ABSTRACT FROM AUTHOR]

Metal halide perovskites, particularly using tin and lead as bivalent cations, are well known for their synthetic versatility and ion mobility. These materials possess intriguing ionic properties that allow the formation of 2D Ruddlesden–Popper (RP) and 3D metal halide perovskite nanocrystals (NCs) under similar synthetic conditions. We studied the synthesis mechanism of oleylammonium-based Sn and Pb bromide perovskites 2D Ruddlesden–Popper (RP) in comparison with the 3D CsPbBr3 and CsSnBr3 NCs. Using experimental techniques in combination with theoretical calculations, we studied the interactions of the long-chain organic cations with the inorganic layers and between each other to assess their stability. Our findings suggest that tin bromide is more inclined toward forming higher-order RP phases or 3D NCs than lead bromide. Furthermore, we demonstrate the synthesis of precisely tuned CsSnBr3 3D NCs (7 and 10 nm) using standard surface ligands. When the 3D and 2D tin halide perovskite nanostructures coexist in suspension, the obtained drop-cast thin films showed the preferential positioning of residual RP nanostructures at the interface with the substrate. This study encourages further exploration of low-dimensional hybrid materials and emphasizes the need for understanding mechanisms to develop efficient synthetic routes for high-quality tin-halide perovskite NCs. [ABSTRACT FROM AUTHOR]

We show an unexpected aggregation phenomenon of a long oligoyne (Py[16]) with 16 contiguous triple bonds and endcapped with bulky 3,5‐bi(3,5‐bis‐tert‐butylphenyl)pyridine groups. Aggregation of 1D π‐conjugated oligoyne chains is rare given the minimal π–π intermolecular interactions as well as its flexibility that works against self‐assembly. In dilute solutions, the reversible aggregation of Py[16] initiates at low temperature in the range of 140–180 K, and is not observed for shorter oligoynes in this series. Cryogenic UV/Vis electronic absorption spectra and vibrational Raman spectra with different laser wavelength lines tuning from in‐resonance to off‐resonance conditions have been used to extract the vibrational features characterizing the monomer and aggregate species. Theoretical calculations complement the spectroscopic findings. [ABSTRACT FROM AUTHOR]

Herein, Cu(II)Pcs and Ni(II)Pcs peripherally tetra‐functionalized with 5‐hexylthiophene (HT), 5‐hexyl‐2,2′‐bithiophene (HBT), and tertbutyl groups (TB) are readily synthesized and employed as hole‐transporting materials (HTMs) in mixed‐ion perovskite ([FAPbI3]0.85[MAPbBr3]0.15) solar cells, achieving power conversion efficiencies (PCEs) up to 20.0%. Remarkably, both the peripheral functionalization and the central metal are found to play a role in the performance. Through a combination of experimental and theoretical techniques, it is found that the simplest HTM, TB‐CuPc, is the best‐performing HTM primarily due to its higher hole mobility and a more appropriate highest‐occupied molecular orbital, whose enables efficient hole extraction without open‐circuit voltage (Voc)losses. This derivative leads to PCEs of 19.96%, which are among the highest values for Pc‐based HTMs. Importantly, devices incorporating these HTMs present significantly higher stability compared to those based on spiro‐OMeTAD. The results here presented pave the way for more realistic, efficient, and inexpensive photovoltaic devices using phthalocyanine derivatives. [ABSTRACT FROM AUTHOR]