Unveiling the nature of supramolecular crown ether–C60 interactions
A series of exTTF-(crown ether)2 receptors, designed to host C60, has been prepared. The size of the crown ether and the nature of the heteroatoms have been systematically changed to fine tune the association constants, which were determined by a number of complementary spectroscopic techniques. Electrochemical measurements and transient absorption spectroscopy assisted in corroborating charge transfer in the ground state and in the excited state, leading to the formation of radical ion pairs featuring lifetimes in the range from 12 to 21 ps. To rationalize the nature of the exTTF-(crown ether)2$C60 stabilizing interactions, theoretical calculations have been carried out, suggesting a syner…
Rhodanine-based dyes absorbing in the entire visible spectrum
A series of new broad-absorbing dyes based on rhodanine derivatives conjugated with triarylamines using Q5 a fluorene backbone was synthesized. Spectroscopic and electrochemical characterizations, along with theoretical calculations at the B3LYP/cc-pVDZ level, revealed interesting properties of the dyes, which make the dyes efficiently absorb in the entire visible spectrum.
SARS-CoV-2 infection and venous thromboembolism after surgery: an international prospective cohort study
SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 da…
Indice general alfabetico, de las cosas notables, que contienen todas las obras del muy ilustre ... Fr. Benito Geronimo Feijoó : inclusas las Dedicatorias, Aprobaciones, y Prólogos ...
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Hole transporting materials based on benzodithiophene and dithienopyrrole cores for efficient perovskite solar cells
The development of highly efficient hole transporting materials (HTMs) for perovskite solar cells (PSCs) is still one of the most thrilling research subjects in the development of this emerging photovoltaic technology. Inner ring engineering of the aromatic core of new HTMs – consisting of three fused rings endowed with four triarylamine units – reveals major performance effects over the fabricated devices. In particular, substitution of the central pyrrole ring in dithienopyrrole (DTP) by a benzene ring – benzodithiophene (BDT) – allows enhancing the power conversion efficiency from 15.6% to 18.1%, in devices employing mixed-perovskite (FAPbI3)0.85(MAPbBr3)0.15 (MA: CH3NH3+, FA: NHCHNH3+) …
A Fully Conjugated TTF-π-TCAQ System: Synthesis, Structure, and Electronic Properties
The synthesis of the first fully conjugated tetrathiafulvalene-tetracyano-p-quinodimethane ((TTF)-TCNQ)-type system has been carried out by means of a Julia-Kocienski olefination reaction. In particular, a tetracyanoanthraquinodimethane (TCAQ) formyl derivative and two new sulfonylmethyl-exTTFs (exTTF = 2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole)--prepared as new building blocks--were linked. A variety of experimental conditions reveal that the use of sodium hexamethyldisilazane (NaHMDS) as base in THF afforded the E olefins with excellent stereoselectivity. Theoretical calculations at the B3LYP/6-31G** level point to highly distorted exTTF and TCAQ that form an almo…
Efficient Benzodithiophene/Benzothiadiazole-Based n-Channel Charge Transporters
A series of donor–acceptor (D-A) small molecules based on electron-deficient benzothiadiazole (BTD) and electron-rich benzodithiophene (BDT) featuring an A-D-A structure is presented. Exhaustive spectroscopic, electrochemical, and computational studies evidence their electroactive nature and their ability to form well-ordered thin films with broad visible absorptions and low band gaps (ca. 2 eV). Time-resolved microwave conductivity (TRMC) studies unveil unexpected n-type charge transport displaying high electron mobilities around 0.1 cm2 V−1 s−1. Efficient electron transport properties are consistent with the low electron reorganization energies (0.11–0.17 eV) theoretically predicted.
Hole-Transporting Materials for Perovskite Solar Cells Employing an Anthradithiophene Core
A decade after the report of the first efficient perovskite-based solar cell, development of novel hole-transporting materials (HTMs) is still one of the main topics in this research field. Two of the main advance vectors of this topic lie in obtaining materials with enhanced hole-extracting capability and in easing their synthetic cost. The use of anthra[1,9-bc:5,10-b'c']dithiophene (ADT) as a flat π-conjugated frame for bearing arylamine electroactive moieties allows obtaining two novel highly efficient HTMs from very cheap precursors. The solar cells fabricated making use of the mixed composition (FAPbI3)0.85(MAPbBr3)0.15 perovskite and the novel ADT-based HTMs show power conversion effi…
Minimizing geminate recombination losses in small-molecule-based organic solar cells
Small-molecule-based organic solar cells (OSCs) are a recurrent alternative to polymer-based OSCs. Due to the higher purity and definition of small molecules compared to polymers, the morphological requirements can be more relaxed. Here, we present a series of novel rhodanine-based small-molecule electron donors and blend them with the standard acceptor PC70BM. By performing a target analysis on femtosecond spectroscopy data, we quantify the rates of geminate charge recombination. We are able to reproduce these rates by applying the Marcus–Levich–Jortner equation, using results from quantum chemical calculations. This shows that in a series of differently substituted compounds, one can corr…