Substituents interplay in piperidinyl-perylenediimide as dopant-free hole-selective layer for perovskite solar cells fabrication

The charge selective layer is of significance for the fabrication of emerging photovoltaics, including perovskite-based solar cells. Molecular hole transport materials (HTMs) are being employed as charge transporters, owing to their synthetic molecular flexibility that allows the fine-tuning of their electro-optical properties. Typically, doping of HTMs is essential, but it is a trade-off between long-term durability and device performance. The energetic level of perylenediimides (PDIs) was altered by the position of the substituent. The substituent’s position influences the geometry of the PDI core, which can lose planarity, thus presenting a core twist angle between the two naphthalene subunits to find its application as hole-selective layers for fabrication. We have fabricated perovskite solar cells, with pristine PDI, and it gave a competitive performance. New design protocols for PDIs are required for aligned energetic levels, which will minimize recombination losses in solar cells, favoring a performance enhancement. Graphical abstract

The Kinetics and Stoichiometry of Metal Cation Reduction on Multi-Crystalline Silicon in a Dilute Hydrofluoric Acid Matrix

In this study, the process of metal cation reduction on multi-crystalline silicon in a dilute hydrofluoric acid (HF) matrix is described using Ag(I), Cu(II), Au(III) and Pt(IV). The experimental basis utilized batch tests with various solutions of different metal cation and HF concentrations and multi-crystalline silicon wafers. The metal deposition kinetics and the stoichiometry of metal deposition and silicon dissolution were calculated by means of consecutive sampling and analysis of the solutions. Several reaction mechanisms and reaction steps of the process were discussed by overlaying the results with theoretical considerations. It was deduced that the metal deposition was fastest if the holes formed during metal ion reduction could be transferred to the valence bands of the bulk and surface silicon with hydrogen termination. By contrast, the kinetics were lowest when the redox levels of the metal ion/metal half-cells were weak and the equilibrium potential of the H3O+/H2 half-cells was high. Further minima were identified at the thresholds where H3O+ reduction was inhibited, the valence transfer via valence band mechanism was limited by a Schottky barrier and the dissolution of oxidized silicon was restricted by the activity of the HF species F−, HF2− and H2F3−. The findings of the stoichiometric conditions provided further indications of the involvement of H3O+ and H2O as oxidizing agents in addition to metal ions, and the hydrogen of the surface silicon termination as a reducing agent in addition to the silicon. The H3O+ reduction is the predominant process in dilute metal ion solutions unless it is disabled due to the metal-dependent equilibrium potential of the H3O+/H2 half-cell and the energetic level of the valence bands of the silicon. As silicon is not oxidized up to the oxidation state +IV by the reduction of the metal ions and H3O+, water is suspected of acting as a secondary oxidant. The stoichiometric ratios increased up to a maximum with higher molalities of the metal ions, in the manner of a sigmoidal function. If, owing to the redox level of the metal half-cells and the energetic level of the valence band at the metal–silicon contact, the surface silicon can be oxidized, the hydrogen of the termination is the further reducing agent.

Interfacial Energetic Level Mapping and Nano-Ordering of Small Molecule/Fullerene Organic Solar Cells by Scanning Tunneling Microscopy and Spectroscopy

Using scanning tunneling microscopy (STM) and spectroscopy (STS) at the liquid/solid interface, morphology evolution process and energetic level alignment of very thin solid films (thickness: <700 pm), of the low molecular weight molecule DRCN5T and DRCN5T:[70]PCBM blend are analyzed after applying thermal annealing at different temperatures. These films exhibit a worm-like pattern without thermal annealing (amorphous shape); however, after applying thermal annealing at 120 °C, the small molecule film domains crystallize verified by X-ray diffraction: structural geometry becomes a well-defined organized array. By using STS, the energy band diagrams of the semiconductor bulk heterojunction (blended film) at the donor-acceptor interface are determined; morphology and energy characteristics can be correlated with the organic solar cells (OSC) performance. When combining thermal treatment and solvent vapor annealing processes as described in previous literature by using other techniques, OSC devices based on DRCN5T show a very acceptable power conversion efficiency of 9.0%.

New Phenolic Derivatives of Thiazolidine-2,4-dione with Antioxidant and Antiradical Properties: Synthesis, Characterization, In Vitro Evaluation, and Quantum Studies

Oxidative stress has been incriminated in the physiopathology of many diseases, such as diabetes, cancer, atherosclerosis, and cardiovascular and neurodegenerative diseases. There is a great interest in developing new antioxidants that could be useful for preventing and treating conditions for which oxidative stress is suggested as the root cause. The thiazolidine-2,4-dione derivatives have been reported to possess various pharmacological activities and the phenol moiety is known as a pharmacophore in many naturally occurring and synthetic antioxidants. Twelve new phenolic derivatives of thiazolidine-2,4-dione were synthesized and physicochemically characterized. The antioxidant capacity of the synthesized compounds was assessed through several in vitro antiradical, electron transfer, and Fe2+ chelation assays. The top polyphenolic compounds 5f and 5l acted as potent antiradical and electron donors, with activity comparable to the reference antioxidants used. The ferrous ion chelation capacity of the newly synthesized compounds was modest. Several quantum descriptors were calculated in order to evaluate their influence on the antioxidant and antiradical properties of the compounds and the chemoselectivity of the radical generation reactions has been evaluated. The correlation with the energetic level of the frontier orbitals partially explained the antioxidant activity, whereas a better correlation was found while evaluating the O–H bond dissociation energy of the phenolic groups.

Dimensioning Studies for Reversible Hydro Power Plants in Portuguese Islands

This work is within the scope of set of consultancy studies made for Portuguese islands. It focuses on the integration of Pumped Storage Power in isolated islands. The paper starts to address several power systems circumstances about two Portuguese islands on the energetic level. For each of these islands, an independent examination of the conditions to install a reversible hydro power plant is accomplished. Therefore, the energy volume to be stored due to excess of renewable generation and the ideal power and number of the pumps and turbines to be installed were identified and evaluated for the sake of using the produced energy surplus as to be pumped and later generated. The paper enhances the importance of storing energy in the operation of isolated and small systems with considerable amount of intermittent power resources as well as the conditions for the viability of installing new exploitations of this kind.

Psychology of the Internal Organs

This chapter helps readers to realize that, at the energetic level, mental and physical functions are two sides of the same energetic balance of the internal organs. Every internal organ has a specific impact on certain mental functions and emotions via its energetic connection with a part of the brain. One can hardly treat physical dysfunction without affecting certain mental functions and vice versa. What has caused the physical dysfunction may also cause the mental illness. This chapter describes how anger, joy, grief, worry, and fear affect internal organs like the Liver, Heart, Lungs, Spleen, and Kidney, and how the dysfunction of these internal organs causes disturbance to a patient’s consciousness, unconsciousness, thinking, judgment, and willpower.

Quantum Nature of Vehicle Motion

The paper presents a new adequate look on the character of motion of any material body, such as moving vehicle. It has been proved, that motion of material bodies has a quantum character. Due to this their consecutive energetic states are obtained by a jump. The phenomenon of quantum in the reference to vehicle kinetics has been derived by indicating its place on the background of characteristics of whole mechanics. The length of vehicle way in particular phases of its motion is that source characteristics the derivatives of which form the development of motion description of a material solid/body. It has been indicated that the quantum nature of body motion does not depend on its magnitude. Thus, as has been noticed, there is an analogy between the macro-body motion and electron motion which change its energy also by jump, by getting from one orbit (energetic level) to another.

Quantitative characteristics of the carcasses of Moxotó and Canindé goats fed diets with two different energy levels

The objective of this work was to evaluate the quantitative characteristics of carcasses of Moxotó and Canindé goats finished in feedlots and fed diets of two levels of energy. It was used 40 castrated young goats, 20 from Moxotó breed and 20 from Canindé breed, each one with an average body weight of 15.2 kg. The animals were fed with diets containing 2.20 and 2.71 (Mcal/kg DM). The experimental period lasted 86 days. There was no difference among the barometric measures of Moxotó and Canindé kids. Canindé goats showed higher final weight, higher weight after fasting and higher hot and cold carcass weights when compared to the Moxotó animals. Animals that consumed diets with higher energy level had higher final weight and conformation as well as higher carcass yield. Considering the percentage values of the commercial meat cuts, no difference among treatments was observed. The diet was the factor that most influenced the non-constituent components of the carcass of Moxotó and Canindé goats. In general, animals belonging to the Canindé breed presented higher quantitative characteristics than the Moxotó breed. Supply of diets with higher energetic level (2.71 Mcal/kg DM) for goats from Moxotó and Canindé breeds, in feedlots, favors the production of carcass with higher yields and heavier commercial meat cuts.