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A chain is as strong as its weakest link – Stability study of MAPbI3 under light and temperature
摘要： The stability of perovskite solar cells is a key issue for industrial development. One reason for this is the volatile organic methylammonium (MA) cation, which is prone to degas under elevated temperatures from the perovskite. At the same time, small amounts of MA are used for practically all highest performing solar cells. These compositions have also shown relatively promising stabilities. This raises the question of MA stability with respect to different, application-dependent stability requirements. Interestingly, MA stability was mainly studied on thin films that differ from full devices or with architectures which are also prone to degrade. Therefore, the degradation behavior on complete MA containing devices with a relatively stable architecture is required to quantify the long-term stability of MA. This enables to determine at which timescales MA is unstable and which role it can play in future compositions. If MA is indeed unstable at much longer timescales than previously recorded, it also indicates that more severe degradation pathways are currently underappreciated. Here, “weakest link” MAPbI3 devices are used, i.e. showing promising stability: devices retained 100% of their initial efficiency over 1000 h of aging under constant illumination and maximum power point tracking at 20 °C. At elevated temperatures of 50 and 65 °C, the devices retained 100% and 90% of their initial efficiency after 500 h of illumination, respectively. Impressively, at 95 °C the MAPbI3 device retained 85% after 500 h under constant illumination of its initial efficiency, which is some of the best stability data reported to date for MA. Thus, MA-containing devices require further studying. Nevertheless to achieve the necessary industrial lifetimes of more than 25 years, the complete removal of MA is a sensible precaution to systematically avoid any long-term risk factors.
关键词： Electrocatalysis,Renewable energy,Metallic nanocrystals,Two-dimensional
更新于2025-09-23 15:21:01
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Plasmon-enhanced inelastic scattering by 2D and 3D superlattices made of silver nanocrystals
摘要： The lattice dynamics of natural crystals, artificial superlattices, or self‐organized nanocrystals intimately mix confinement, coupling, periodicity, and dissipative effects. The low wavenumber vibrational response of the new class of nanomaterials called “supercrystals” does contain relevant information concerning finite size effects on atomic movements inside each nanocrystal, mechanical coupling between adjacent nanocrystals, coherent behavior of the total assembly due to its superperiodicity, and finally finite‐time effects due to damping. All these aspects concerning the dynamical behavior of silver supercrystals has been analyzed using plasmon resonance Raman scattering. Owing to the highly uniform size and chemical environment of the nanocrystals, the confinement and homogeneous damping of their fundamental vibrations are carefully analyzed. The signature of their internal atomic arrangements, as a reminiscence of bulk phonons, is also explored. It is shown that for low particles diameter (?5 nm), deviations from the continuum elastic approximation occur and that the vibrational response is more sensitive to atomic arrangements and surface effects inside the nanocrystals than to spatial coherence effects between them.
关键词： atomistic simulations,supercrystals,damping,low wavenumber,metallic nanocrystals
更新于2025-09-23 15:21:01
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Boosting the photocatalytic performances of covalent organic frameworks enabled by spatial modulation of plasmonic nanocrystals
摘要： Plasmonic Au nanocrystals (NCs) are incorporated into covalent organic frameworks (COFs) with precisely modulated distributions to improve the efficiency of electron-hole separation covalent reactions and assembly of NCs, sparsely dispersed Au NCs (AuSP/COFs) or the close packed ones (AuCP/COFs) in COFs are fabricated, in which the contributions of electron acceptors/cocatalysts on the catalytic properties of Au/COFs composites are addressed by EPR, PL, phenacyl bromide (conversion >99%, selectivity of acetophenone ~92.8%) under visible light irradiation, which are associated with accelerated electron transfer, increased available Au/COFs and optimize the charge-carrier utilization. Specifically, through balancing the rate of dynamic Schottky junctions and boosted interfacial reaction kinetics. Overall, this work contributes to the fundamental understanding of the how spatial distributions of NCs in COFs affect the photocatalytic performances.
关键词： metallic nanocrystals,heterojunctions,covalent organic frameworks,photocatalysis,inorganic/organic hybrids
更新于2025-09-23 15:19:57
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Terahertz plasmonics: The rise of toroidal metadevices towards immunobiosensings
摘要： This work reviews fundamentals and the recent state-of-art achievements in the field of plasmonic biosensing based terahertz (THz) spectroscopy. Being nonpoisonous and nondestructive to the human tissues, THz signals offer promising, cost-effective, and real-time biodevices for practical pharmacological applications such as enzyme reaction analysis. Rapid developments in the field of THz plasmonics biosensors and immunosensors have brought many methodologies to employ the resonant subwavelength structures operating based on the fundamental physics of multipoles and asymmetric lineshape resonances. In the ongoing hunt for new and advanced THz plasmonic biosensors, the toroidal metasensors have emerged as excellent alternates and are introduced to be a very promising technology for THz immunosensing applications. Here, we provide examples of recently proposed THz plasmonic metasensors for the detection of thin films, chemical and biological substances. This review allows to compare the performance of various biosensing tools based on THz plasmonic approach and to understand the strategic role of toroidal metasensors in highly accurate and sensitive biosensors instrumentation. The possibility of using THz plasmonic biosensors based on toroidal technology in modern medical and clinical practices has been briefly discussed.
关键词： Two-dimensional,Electrocatalysis,Metallic nanocrystals,Renewable energy
更新于2025-09-11 14:15:04