ACS Materials Letters最新文献

The impetus to add a third component in ternary blend organic solar cells (TBSCs) maximizes the light-harvesting capability of the active layer. Beyond this, the third component can perform other useful functions, such as enhancing the morphology and charge transport, and assisting in resonance energy transfer. Currently, there are no established guidelines for selecting the third component in TBSCs to optimize the organic solar cell (OSC) performance. By varying the chromophore chain length of perylene diimide (PDI) molecules, we revealed its influence on the morphology of the thin film and the efficiency of PM6:Y6 OSCs. Detailed optical and electrical characterization and morphological studies revealed that molecular size and PDIs’ chromophore chain length are pivotal to improving the performance of OSCs. The PDI monomer acts as an additive to improve the morphology and light-harvesting capability of TBSCs. This study presents several significant findings, including the dual role of the third component, the influence of the chromophore chain length on morphology, and the dynamics of excited states.

The utilization of non-fullerene acceptors (NFA) in organic photovoltaic (OPV) devices offers advantages over fullerene-based acceptors, including lower costs and improved light absorption. Despite advances in small molecule generative design, experimental validation frameworks are often lacking. This study introduces a comprehensive pipeline for generating, virtual screening, and synthesizing potential NFAs for high-efficiency OPVs, integrating generative and predictive ML models with expert knowledge. Iterative refinement ensured the synthetic feasibility of the generated molecules, using the diketopyrrolopyrrole (DPP) core motif to manually generate NFA candidates meeting stringent synthetic criteria. These candidates were virtually screened using a predictive ML model based on power conversion efficiency (PCE) calculations from the modified Scharber model (PCE_MS). We successfully synthesized seven NFA candidates, each requiring three or fewer steps. Experimental HOMO and LUMO measurements yielded calculated PCE_MS values from 6.7% to 11.8%. This study demonstrates an effective pipeline for discovering OPV NFA candidates by integrating generative and predictive ML models.

Metal electrodeposition and dissolution on a transparent electrode enable dynamic switching between the opaque and transparent states, respectively. To be used as dynamic windows, a fully black state must be achieved while maintaining reversibility. Cu is a top candidate that meets the latter criterion but fails the former, producing its characteristic orange tint. As a result, metal additives are often mixed with Cu ions but at the expense of some degree of reversibility. Here, a truly black state is achieved without metal additives by enhancing the dissipative interaction between light and Cu. A galvanic etching method is used to transform a flat ITO surface into an array of nanopillars, forming a gradually varying index across the ITO interface. This elongates the light absorption path length over all wavelengths once Cu is electrodeposited. The electrode is demonstrated in dynamically tunable devices including one that transitions between mirror-like and opaque states with a coloration efficiency of 20.3 cm² C^–1. These results highlight the potential of our strategy in light management devices, particularly for energy-conserving dynamic windows.

Studying lithium growth on diverse substrates with unique crystal structures is crucial for linking atomic and macroscopic views, which ensures a long cycle life and safety in lithium metal batteries. This work provides explanations on (1) the stages of nucleation, which are influenced by the adsorption-relaxation mechanism, (2) acquiring evolved traits of dendritic morphology from the embryo, and (3) the integration of the atomic and macroscopic perspectives through a variety of techniques at different scales to validate dendrite evolution. The heteroepitaxial growth process of the embryos is divided into two principal stages: nucleation and growth. The adsorption-type substrates exhibit characteristics of relatively lower average interaction energy and specific stress energy during the nucleation stage. At the growth stage, the adsorption-type substrate tends to facilitate multilayer growth. This work provides potential to design and material selection for lithium metal batteries, contributing to the development of safer, more efficient, and longer-lasting energy storage systems.

Photoelectrodes used in solar water splitting must operate in aqueous media. However, computational studies that explicitly compare the dry and solvated photoelectrode energetics at finite temperature and the impact of the photoelectrode surface composition and surface defects are lacking. Here, we used first-principles molecular dynamics simulations to investigate the solvation and thermal effects on the energetics of the BiVO₄(010) surface with different surface compositions and oxygen vacancies, a common defect responsible for the intrinsic n-type behavior of BiVO₄. We find that the alignment of the photoelectrode electronic bands with the water redox potentials is modified in the presence of water and that solvation effects and thermal fluctuations are more prominent for Bi-rich surfaces, especially so in the presence of oxygen vacancies. Our results provide a detailed understanding of the behavior of BiVO₄ photoanodes operating in aqueous media, as a function of surface composition, and are directly comparable with experiments.

The pursuit of reliable and sustainable energy storage solutions has spurred significant research activity in the development of aqueous batteries (ABs). However, the energy density and cycling stability of ABs have remained stubbornly limited, leading to a plethora of host material designs and electrolyte modulation strategies. As an intermolecular interaction force, the hydrogen bond (HB) presents a promising avenue for optimizing the performance of electrode materials and electrolytes. However, HB chemistry in ABs remains poorly understood to date. Therefore, this Review aims to provide an updated summary of the current understanding of HB chemistry (mechanism, type, strength), the effect of HB on electrolytes (conductivity, freezing point, decomposition potential, viscosity, and dissolubility), and host materials’ performance (stacking, insulation, ionic conductivity). In addition, we construct a vivid illustration of the structure–activity relationship between molecular-scale HB interactions and macroscale battery performance. A series of representative case studies in which HBs are used to optimize electrochemical performance are discussed. Finally, advanced methodologies for characterization of HBs are described in detail. This Review provides new insights into the relationship between HB chemistry and battery performance. It also provides guideline for building high-energy and high-rate ABs taking advantage of HB chemistry.

Ni-rich layered cathode materials have attracted extensive attention due to their higher energy density and technological maturity in commercialization. As the nickel content is raised, especially surpassing 80%, the increased energy density comes with the tradeoff of diminished thermal stability and increased electrochemical structural instability of the cathode. Compared with Co, Al, B, and Ta, the introduction of high valence element Nb significantly improved the electrochemical cycling, delivering a capacity of 202 mAh/g, corresponding to a capacity retention of 92% after 200 cycles tested at 45 °C. The ex situ differential scanning calorimetry and in situ isothermal microcalorimetry demonstrate that the Nb-modified cathode has the potential to enhance the safety of ultrahigh nickel (Ni) NMCs and displays remarkable resilience to extensive cycling by inhibiting high-temperature decomposition reactions and exhibiting a lower heat flow during electrochemical cycling.

High-capacity Li-rich Mn-based oxides (LRMOs) show great potential for enhancing the energy density of all-solid-state lithium batteries (ASSLBs). However, the intrinsically low electronic/ionic conductivity of LRMOs and bulk structural degradation lead to an inferior electrochemical performance. Herein, a single-crystal Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ (SC- LRMO) cathode is developed to address the challenges associated with charge-transport limitations and mechanical degradation of conventional polycrystalline (PC)-LRMO in ASSLBs. The results indicate that composite cathodes using small SC-LRMO achieve excellent electrochemical performance. Specifically, SC-LRMO not only delivers a high specific capacity of 316 mAh g^–1 at 0.05C but also exhibits a capacity retention of 86% after 300 cycles at 1C, outperforming the PC-LRMO (243 mAh g^–1, 84%). Comprehensive characterization reveals that the small single-crystal microstructure of SC-LRMO facilitates electrochemical reaction and mitigates detrimental mechanical degradation. Overall, this work expedites the practical application of LRMO cathodes in high-energy-density ASSLBs through dedicated morphology design.

Li-CO₂ batteries capture and convert CO₂ into a valuable energy storage medium, promoting both energy storage and environmental sustainability. While Ru-based catalysts exhibit exceptional catalytic activity and are widely deployed in Li-CO₂ batteries, the Ru nanoparticle size effects on electrolysis remains underexplored. Herein, we synthesized Ru nanoparticles ranging from ∼1.1 to ∼7.4 nm to unveil the size-dependent activity in Li-CO₂ batteries. As Ru size decreases, the d-band center of Ru is identified upshifted toward the Fermi level, and the Gibbs energy change for the rate-determining step during charge is lowered. The binding energy of C═O and Li–O is notably reduced, confirming that a strong interaction between small Ru and Li₂CO₃ can destabilize Li₂CO₃ and facilitate its decomposition. Furthermore, small Ru nanoparticles can alleviate Li₂CO₃ accumulation on cathodes. This work provides insight and guidance for catalyst design and optimization in Li-CO₂ batteries, which can be extended to other battery systems involving solid product formation and decomposition.