RESUMEN
The challenges of Lithium-carbon dioxide (Li-CO2) batteries for ensuring long-term cycling stability arise from the thermodynamically stable and electrically insulating discharge products (e.g., Li2CO3), which primarily rely on their interaction with the active materials. To achieve the optimized intermediates, the bifunctional electron donor-acceptor (D-A) pairs are proposed in cathode design to adjust such interactions in the case of B-O pairs. The inclusion of BC2O sites allows for the optimized redistribution of electrons via p-π conjugation. The as-obtained DO-AB pairs endow the enhanced interactions with Li+, CO2, and various intermediates, accompanied by the adjustable growth mode of Li2CO3. The shift from solvation-mediated mode into surface absorption mode in turn manipulates the morphology and decomposition kinetics of Li2CO3. Therefore, the corresponding Li-CO2 battery got twofold improved in both the capacity and reversibility. The cycling prolongs exceed 1300 h and well operates at a wide temperature range (20-50 °C) and different folding angles (0-180°). Such a strategy of introducing electron donor-acceptor pairs provides a distinct direction to optimize the lifetime of Li-CO2 battery from local structure regulation at the atomic scale, further inspiring in-depth understandings for developing electrochemical energy storage and carbon capture technologies.
RESUMEN
The C3 -symmetric star-shaped phenothiazene-substituted truxene 1 was reacted with the electron acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The cycloaddition-retroelectrocyclization reaction yields the conjugates 2 and 3. A combination of spectral, electrochemical, and photophysical investigations of 2 and 3 reveals that the functionalization of the triple bond has a pronounced effect on their ground and excited-state interactions. Specifically, the existence of strong ground-state interactions between phenothiazine and the electron-accepting groups results in charge-transfer states, while subsequent ultrafast charge separation yields electron transfer products. This is unprecedented not only in phenothiazine chemistry but also in tetracyanobutadiene- and dicyanoquinodimethane-derived donor-acceptor conjugates. Additionally, by manipulating spectroelectrochemical data, a spectrum of the charge-separated species is construed for the first time, and shown to be highly useful in interpreting the rather complex transient spectra.
RESUMEN
Compared with conventional organic solar cells (OSCs) based on single donor-acceptor pairs, terpolymer- and ternary-based OSCs featuring multiple donor-acceptor pairs are promising strategies for enhancing the performance while maintaining an easy and simple synthetic process. Using multiple donor-acceptor pairs in the active layer, the key photovoltaic parameters (i.e., short-circuit current density, open-circuit voltage, and fill factor) governing the OSC characteristics can be simultaneously or individually improved by positive changes in light-harvesting ability, molecular energy levels, and blend morphology. Here, these three major contributions are discussed with the aim of offering in-depth insights in combined terpolymers and ternary systems. Recent exemplary cases of OSCs with multiple donor-acceptor pairs are summarized and more advanced research and perspectives for further developments in this field are highlighted.
RESUMEN
Typically, light microscopic methodologies using conventional optics are limited by the diffraction limit yielding resolutions that cannot be reached lower than approximately 200nm. However, using appropriate donor-acceptor pairs, nonradiative fluorescence resonance energy transfer (FRET) allows the microscopist to detect, and in some cases quantify, molecular interactions on the order of Angstroms. In this chapter, the basic principles of FRET are introduced using both steady state and lifetime modes to detect the close association of fluorescent donor and acceptor molecules. The basic design of experiments and optical and imaging components is discussed to create a microscope that is capable of monitoring dynamic molecular associations in living cells.