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Organic solar cells (OSCs) using non-fullerene acceptors (NFAs) afford exceptional photovoltaic performance metrics, however, their stability remains a significant challenge. Existing OSC stability studies focus on understanding degradation rate-performance relationships, improving interfacial layers, and suppressing degradative chemical reaction pathways. Nevertheless, there is a knowledge gap concerning how such degradation affects crystal structure, electronic states, and recombination dynamics that ultimately impact NFA performance. Here we seek a quantitative relationship between OSC metrics and blend morphology, trap density of states, charge carrier mobility, and recombination processes during the UV-light-induced degradation of PBDB-TF:Y6 inverted solar cells as the PCE (power conversion efficiency) falls from 17.3 to 5.0%. Temperature-dependent electrical and impedance measurements reveal deep traps at 0.48 eV below the conduction band that are unaffected by Y6 degradation, and shallow traps at 0.15 eV below the conduction band that undergo a three-fold density of states increase at the PCE degradation onset. Computational analysis correlates vinyl oxidation with a new trap state at 0.25 eV below the conduction band, likely involving charge transfer from the UV-absorbing ZnO electron transport layer. In-situ integrated photocurrent analysis and transient absorption spectroscopy reveal that these traps lower electron mobility and increase recombination rates during degradation. Grazing-incidence wide-angle x-ray scattering and computational analysis reveal that the degraded Y6 crystallite morphology is largely preserved but that <1% of degraded Y6 molecules cause OSC PCE performance degradation by ≈50%. Together the detailed electrical, impedance, morphological, ultrafast spectroscopic, matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) spectroscopy, and computational data reveal that the trap state energies and densities accompanying Y6 vinyl oxidation are primarily responsible for the PCE degradation in these operating NFA-OSCs. 

Geminal (gem−) disubstitution in heterocyclic monomers is an effective strategy to enhance polymer chemical recyclability by lowering their ceiling temperatures. However, the effects of specific substitution patterns on the monomer's reactivity and the resulting polymer's properties are largely unexplored. Here we show that, by systematically installinggem‐dimethyl groups onto ϵ‐caprolactam (monomer of nylon 6) from the α to ϵ positions, both the redesigned lactam monomer's reactivity and the resultinggem‐nylon 6’s properties are highly sensitive to the substitution position, with the monomers ranging from non‐polymerizable to polymerizable and thegem‐nylon properties ranging from inferior to far superior to the parent nylon 6. Remarkably, the nylon 6 with thegem‐dimethyls substituted at the γ position is amorphous and optically transparent, with a higherT_g(by 30 °C), yield stress (by 1.5 MPa), ductility (by 3×), and lower depolymerization temperature (by 60 °C) than conventional nylon 6.

 

Developing effective catalysis to address end-of-life Nylon pollution is urgent yet remains underdeveloped. Nylon-6 is a resilient synthetic plastic and a major contributor to ocean pollution. Here, we report a metallocene catalytic system based on earth-abundant early transition and lanthanide metals that mediates Nylon-6 depolymerization at unprecedented rates up to 810 (ε-caprolactam)$ mol(Cat.)1$h1 at 240C in R99% yield. This solventless process operates with catalyst loadings as low as 0.04 mol % at temperatures as low as 220C—themildest Nylon-6 depolymerization conditions reported to date. This metallocene catalysis can be carried out in a simulated continuous process, and the resulting ε-caprolactam can be re-polymerized to higher-quality Nylon-6. Experimental and DFT analyses identify effective depolymerization pathways involving catalytic intra-Nylon-chain ‘‘unzipping’’ assisted by p-ligand effects and inter-chain ‘‘hopping.’’ A robust chelating ansa-yttrocene is particularly effective in depolymerizing diverse commodity end-of-life articles, such as fishing nets, carpets, clothing, and plastic mixtures. 

Flexible and stretchable bioelectronics provides a biocompatible interface between electronics and biological systems and has received tremendous attention for in situ monitoring of various biological systems. Considerable progress in organic electronics has made organic semiconductors, as well as other organic electronic materials, ideal candidates for developing wearable, implantable, and biocompatible electronic circuits due to their potential mechanical compliance and biocompatibility. Organic electrochemical transistors (OECTs), as an emerging class of organic electronic building blocks, exhibit significant advantages in biological sensing due to the ionic nature at the basis of the switching behavior, low driving voltage (<1 V), and high transconductance (in millisiemens range). During the past few years, significant progress in constructing flexible/stretchable OECTs (FSOECTs) for both biochemical and bioelectrical sensors has been reported. In this regard, to summarize major research accomplishments in this emerging field, this review first discusses structure and critical features of FSOECTs, including working principles, materials, and architectural engineering. Next, a wide spectrum of relevant physiological sensing applications, where FSOECTs are the key components, are summarized. Last, major challenges and opportunities for further advancing FSOECT physiological sensors are discussed.

 

New emerging low‐dimensional such as 0D, 1D, and 2D nanomaterials have attracted tremendous research interests in various fields of state‐of‐the‐art electronics, optoelectronics, and photonic applications due to their unique structural features and associated electronic, mechanical, and optical properties as well as high‐throughput fabrication for large‐area and low‐cost production and integration. Particularly, photodetectors which transform light to electrical signals are one of the key components in modern optical communication and developed imaging technologies for whole application spectrum in the daily lives, including X‐rays and ultraviolet biomedical imaging, visible light camera, and infrared night vision and spectroscopy. Today, diverse photodetector technologies are growing in terms of functionality and performance beyond the conventional silicon semiconductor, and low‐dimensional nanomaterials have been demonstrated as promising potential platforms. In this review, the current states of progress on the development of these nanomaterials and their applications in the field of photodetectors are summarized. From the elemental combination for material design and lattice structure to the essential investigations of hybrid device architectures, various devices and recent developments including wearable photodetectors and neuromorphic applications are fully introduced. Finally, the future perspectives and challenges of the low‐dimensional nanomaterials based photodetectors are also discussed.

 

Carbonyl bond hydroboration is a valuable synthetic route to functionalized alcohols but relies on sometimes unselective and sluggish reagents. While rapid and selective aldehyde and ketone hydroboration mediated by trisamidolanthanide catalysts is known, the origin of the selectivity is not well-understood and is the subject of this contribution. Here the aldehyde and ketone HBpin hydroboration reaction mechanisms catalyzed by La[N(SiMe 3 ) 2 ] 3 are investigated both experimentally and theoretically. The results support initial carbonyl oxygen coordination to the acidic La center, followed by intramolecular ligand-assisted hydroboration of the carbonyl moiety by bound HBpin. Interestingly, ketone hydroboration has a higher energetic barrier than that of aldehydes due to the increased steric encumbrance and decreased electrophilicity. Utilizing NMR spectroscopy and X-ray diffraction, a bidentate acylamino lanthanide complex associated with the aldehyde hydroboration is isolated and characterized, consistent with the relative reaction rates. Furthermore, an aminomonoboronate–lanthanide complex produced when the La catalyst is exposed to excess HBpin is isolated and characterized by X-ray diffraction, illuminating unusual aminomonoboronate coordination. These results shed new light on the origin of the catalytic activity patterns, reveal a unique ligand-assisted hydroboration pathway, and uncover previously unknown catalyst deactivation pathways.