Our students have been involved in new and exciting interdisciplinary research and have published in leading high impact journals including Nature Chemistry, Nature Communications, JACS, Angewandte Chemie, Applied Physics Letters, ACS Nano, Nano Letters, Advanced Materials, Nature Protocols, PloS one, and many others.
A full list of the work published by our NanoDTC Students, Associates and others, acknowledging the NanoDTC grants EP/G037221, EP/L015978 and EP/S022953/1 is below. If you want to view the papers on google scholar, see here.
Some papers published by our students are also featured below with some additional contextual information.
Last updated: Mar 2021
Looking inside lithium-ion batteries
Spectroscopy and Electrocatalysis for a Sustainable Future
From waste to fuel: quantifying sustainability
Novel spin states discovered in silicon-based artificial atoms
A step forward in efficient artificial photosynthesis
Self-assembling hydrogels on microfluidic droplets that respond to light or chemical stimuli by disassembling
2022 |
||
| 622. | Goor, Tim Van De Local structure of hybrid metal-halide perovskites PhD Thesis University of Cambridge, 2022. @phdthesis{Goor2022, title = {Local structure of hybrid metal-halide perovskites}, author = {Tim Van De Goor}, url = {https://www.repository.cam.ac.uk/handle/1810/332270}, year = {2022}, date = {2022-00-00}, school = {University of Cambridge}, abstract = {This thesis reports on the effects of static and dynamic disorder on the structure and op- toelectronic properties of the hybrid metal halide perovskite family MAPbX3 (MA+ = methylammonium, CH3NH+3 , X = Cl−, Br−). Static disorder was introduced by halide substitution through solid state synthesis, providing better stoichiometric control compared to solution based techniques. Composition and temperature dependent X-ray diffraction and heat capacity measurements of MAPb(ClxBr1−x)3 revealed a suppression of the symmetry- lowering phase transitions of the end members in a wide range of intermediate compositions (0.2 < x < 0.8) down to T = 12 K. The suppression was not observed for the closely related inorganic CsPb(ClxBr1−x)3 system, highlighting the importance of the MA+ cation in direct- ing the crystal structure. Density functional theory calculations confirmed the experimental observations of the hybrid and inorganic mixed-halide systems. The findings are consis- tent with the formation of an orientational glass on the MA+ sublattice. Temperature and composition dependent photoluminescence measurements showed that photo-induced halide segregation occurred only in the orientational glass forming compositions. The local structure of the hybrid metal halide perovskites in the presence of static disorder was investigated using pair distribution function analysis of composition and temperature dependent X-ray and neutron total scattering of d6-MAPb(ClxBr1−x)3. It was found that both the local structure (r < 10 Å) and the average structure (r > 10 Å) at room temperature were well described by the same space group, in contrast to …}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } This thesis reports on the effects of static and dynamic disorder on the structure and op- toelectronic properties of the hybrid metal halide perovskite family MAPbX3 (MA+ = methylammonium, CH3NH+3 , X = Cl−, Br−). Static disorder was introduced by halide substitution through solid state synthesis, providing better stoichiometric control compared to solution based techniques. Composition and temperature dependent X-ray diffraction and heat capacity measurements of MAPb(ClxBr1−x)3 revealed a suppression of the symmetry- lowering phase transitions of the end members in a wide range of intermediate compositions (0.2 < x < 0.8) down to T = 12 K. The suppression was not observed for the closely related inorganic CsPb(ClxBr1−x)3 system, highlighting the importance of the MA+ cation in direct- ing the crystal structure. Density functional theory calculations confirmed the experimental observations of the hybrid and inorganic mixed-halide systems. The findings are consis- tent with the formation of an orientational glass on the MA+ sublattice. Temperature and composition dependent photoluminescence measurements showed that photo-induced halide segregation occurred only in the orientational glass forming compositions. The local structure of the hybrid metal halide perovskites in the presence of static disorder was investigated using pair distribution function analysis of composition and temperature dependent X-ray and neutron total scattering of d6-MAPb(ClxBr1−x)3. It was found that both the local structure (r < 10 Å) and the average structure (r > 10 Å) at room temperature were well described by the same space group, in contrast to … | |
| 621. | Rubio-Sanchez, Roger DNA-based Artificial Mimics of Cell-surface Machinery PhD Thesis University of Cambridge, 2022. @phdthesis{Rubio-Sanchez2022, title = {DNA-based Artificial Mimics of Cell-surface Machinery}, author = {Roger Rubio-Sanchez}, url = {https://www.repository.cam.ac.uk/handle/1810/334542}, year = {2022}, date = {2022-00-00}, school = {University of Cambridge}, abstract = {The plasma membrane of cells has evolved to mediate a broad array of functionalities critical to life, such as molecular trafficking, signal transduction, motility, adhesion and communication. These functionalities are often reliant on highly sophisticated membrane-anchored nano-machines, and enabled by the ability of the cell to regulate their spatio-temporal distribution and interactions. Bottom-up synthetic biology aspires to replicate the rich phenomenology associated with biological systems in artificial cells, micron-sized entities created de-novo to display life-like behaviours. Artificial cells have been constructed using a range of elementary molecular components, from lipids to polymers and proteins, yet artificial cellular membranes are usually passive enclosures lacking the diverse functionalities hosted by their biological counterparts. DNA nanotechnology has emerged as a prime route for biomimicry given its yet unparalleled control over the structure and dynamic responses of synthetic nanostructures. Particularly promising in the context of bottom-up synthetic biology is the possibility of constructing bio-inspired DNA devices that mimic the structure and action of membrane-bound biological machines, and integrate them with artificial-cell membranes to unlock some of the rich functionalities sustained by the plasma membrane. In this thesis, I explore the use of functional DNA nanostructures to program the properties and responses of the lipid membranes of synthetic cells. By depending our understanding of how cations, hydrophobic modifications of the nanostructures, and bilayer-phase influence DNA-lipid interactions, I was able to …}, keywords = {}, pubstate = {published}, tppubtype = {phdthesis} } The plasma membrane of cells has evolved to mediate a broad array of functionalities critical to life, such as molecular trafficking, signal transduction, motility, adhesion and communication. These functionalities are often reliant on highly sophisticated membrane-anchored nano-machines, and enabled by the ability of the cell to regulate their spatio-temporal distribution and interactions. Bottom-up synthetic biology aspires to replicate the rich phenomenology associated with biological systems in artificial cells, micron-sized entities created de-novo to display life-like behaviours. Artificial cells have been constructed using a range of elementary molecular components, from lipids to polymers and proteins, yet artificial cellular membranes are usually passive enclosures lacking the diverse functionalities hosted by their biological counterparts. DNA nanotechnology has emerged as a prime route for biomimicry given its yet unparalleled control over the structure and dynamic responses of synthetic nanostructures. Particularly promising in the context of bottom-up synthetic biology is the possibility of constructing bio-inspired DNA devices that mimic the structure and action of membrane-bound biological machines, and integrate them with artificial-cell membranes to unlock some of the rich functionalities sustained by the plasma membrane. In this thesis, I explore the use of functional DNA nanostructures to program the properties and responses of the lipid membranes of synthetic cells. By depending our understanding of how cations, hydrophobic modifications of the nanostructures, and bilayer-phase influence DNA-lipid interactions, I was able to … | |
| 620. | Felix U Kosasih Giorgio Divitini, Jordi Ferrer Orri Elizabeth Tennyson Gunnar Kusch Rachel Oliver Samuel Stranks Caterina Ducati M A D Optical emission from focused ion beam milled halide perovskite device cross‐sections Journal Article Microscopy Research and Technique, 2022. @article{Kosasih2022, title = {Optical emission from focused ion beam milled halide perovskite device cross‐sections}, author = {Felix U Kosasih, Giorgio Divitini, Jordi Ferrer Orri, Elizabeth M Tennyson, Gunnar Kusch, Rachel A Oliver, Samuel D Stranks, Caterina Ducati}, url = {https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/abs/10.1002/jemt.24069}, year = {2022}, date = {2022-00-00}, journal = {Microscopy Research and Technique}, abstract = {Cross‐sectional transmission electron microscopy has been widely used to investigate organic–inorganic hybrid halide perovskite‐based optoelectronic devices. Electron‐transparent specimens (lamellae) used in such studies are often prepared using focused ion beam (FIB) milling. However, the gallium ions used in FIB milling may severely degrade the structure and composition of halide perovskites in the lamellae, potentially invalidating studies performed on them. In this work, the close relationship between perovskite structure and luminescence is exploited to examine the structural quality of perovskite solar cell lamellae prepared by FIB milling. Through hyperspectral cathodoluminescence (CL) mapping, the perovskite layer was found to remain optically active with a slightly blue‐shifted luminescence. This finding indicates that the perovskite structure is largely preserved upon the lamella fabrication process …}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cross‐sectional transmission electron microscopy has been widely used to investigate organic–inorganic hybrid halide perovskite‐based optoelectronic devices. Electron‐transparent specimens (lamellae) used in such studies are often prepared using focused ion beam (FIB) milling. However, the gallium ions used in FIB milling may severely degrade the structure and composition of halide perovskites in the lamellae, potentially invalidating studies performed on them. In this work, the close relationship between perovskite structure and luminescence is exploited to examine the structural quality of perovskite solar cell lamellae prepared by FIB milling. Through hyperspectral cathodoluminescence (CL) mapping, the perovskite layer was found to remain optically active with a slightly blue‐shifted luminescence. This finding indicates that the perovskite structure is largely preserved upon the lamella fabrication process … | |
| 619. | Oliver Vanderpoorten Ali N Babar, Georg Krainer Raphaël PB Jacquat Pavan Challa Quentin Peter Zenon Toprakcioglu Catherine Xu Ulrich Keyser Jeremy Baumberg Clemens Kaminski Tuomas PJ Knowles K K F J F Nanofluidic Traps by Two-Photon Fabrication for Extended Detection of Single Macromolecules and Colloids in Solution Journal Article ACS Applied Nano Materials, 2022. @article{Vanderpoorten2022, title = {Nanofluidic Traps by Two-Photon Fabrication for Extended Detection of Single Macromolecules and Colloids in Solution}, author = {Oliver Vanderpoorten, Ali N Babar, Georg Krainer, Raphaël PB Jacquat, Pavan K Challa, Quentin Peter, Zenon Toprakcioglu, Catherine K Xu, Ulrich F Keyser, Jeremy J Baumberg, Clemens F Kaminski, Tuomas PJ Knowles}, url = {https://pubs.acs.org/doi/abs/10.1021/acsanm.1c03691}, year = {2022}, date = {2022-00-00}, journal = {ACS Applied Nano Materials}, abstract = {The analysis of nanoscopic species, such as proteins and colloidal assemblies, at the single-molecule level has become vital in many areas of fundamental and applied research. Approaches to increase the detection time scales for single molecules in solution without immobilizing them onto a substrate surface and applying external fields are much sought-after. Here, we present an easy-to-implement and versatile nanofluidics-based approach that enables increased observational-time scale analysis of nanoscopic material building blocks such as single biomacromolecules and nanoscale colloids in solution. We use two-photon-based hybrid lithography in conjunction with soft lithography to fabricate nanofluidic devices with nanotrapping geometries down to 100 nm in height. We provide a rigorous description and characterization of the fabrication route that enables the writing of nanoscopic 3D structures directly …}, keywords = {}, pubstate = {published}, tppubtype = {article} } The analysis of nanoscopic species, such as proteins and colloidal assemblies, at the single-molecule level has become vital in many areas of fundamental and applied research. Approaches to increase the detection time scales for single molecules in solution without immobilizing them onto a substrate surface and applying external fields are much sought-after. Here, we present an easy-to-implement and versatile nanofluidics-based approach that enables increased observational-time scale analysis of nanoscopic material building blocks such as single biomacromolecules and nanoscale colloids in solution. We use two-photon-based hybrid lithography in conjunction with soft lithography to fabricate nanofluidic devices with nanotrapping geometries down to 100 nm in height. We provide a rigorous description and characterization of the fabrication route that enables the writing of nanoscopic 3D structures directly … | |
| 618. | Phoebe M Pearce Eduardo Camarillo Abad, Louise Hirst C Designing transparent nanophotonic gratings for ultra-thin solar cells Journal Article Optics Express, 30 (3), pp. 4528-4542, 2022. @article{Pearce2022, title = {Designing transparent nanophotonic gratings for ultra-thin solar cells}, author = {Phoebe M Pearce, Eduardo Camarillo Abad, Louise C Hirst}, url = {https://opg.optica.org/abstract.cfm?uri=oe-30-3-4528}, year = {2022}, date = {2022-00-00}, journal = {Optics Express}, volume = {30}, number = {3}, pages = {4528-4542}, abstract = {Integration of a rear surface nanophotonic grating can increase photocurrent in ultra-thin solar cells. Transparent gratings formed of dielectric materials and high bandgap semiconductors can offer efficient diffraction with lower parasitic absorption than more widely studied metal/dielectric equivalents. In these systems, the maximum photocurrent which can be obtained for a grating made of a given combination of materials is shown to follow a simple empirical model based on the optical constants of these materials and independent of grating dimensions. The grating dimensions still require optimization in order to maximize the photocurrent for a given active layer thickness by balancing the effects of diffraction outside the front surface escape cone and the tuning of waveguide modes in long wavelength regions which are poorly absorbed in an ultra-thin film. The optimal grating pitch is shown to be of particular relevance for both effects, changing nonmonotonically as the absorber gets thicker in order to track favourable waveguide mode resonances at wavelengths near the absorber bandgap. These trends together with the empirical model for material selection drastically reduce the design space for highly efficient light trapping with transparent gratings.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Integration of a rear surface nanophotonic grating can increase photocurrent in ultra-thin solar cells. Transparent gratings formed of dielectric materials and high bandgap semiconductors can offer efficient diffraction with lower parasitic absorption than more widely studied metal/dielectric equivalents. In these systems, the maximum photocurrent which can be obtained for a grating made of a given combination of materials is shown to follow a simple empirical model based on the optical constants of these materials and independent of grating dimensions. The grating dimensions still require optimization in order to maximize the photocurrent for a given active layer thickness by balancing the effects of diffraction outside the front surface escape cone and the tuning of waveguide modes in long wavelength regions which are poorly absorbed in an ultra-thin film. The optimal grating pitch is shown to be of particular relevance for both effects, changing nonmonotonically as the absorber gets thicker in order to track favourable waveguide mode resonances at wavelengths near the absorber bandgap. These trends together with the empirical model for material selection drastically reduce the design space for highly efficient light trapping with transparent gratings. | |
| 617. | Rohit Chikkaraddy Angelos Xomalis, Lukas Jakob Jeremy Baumberg A J Mid-infrared-perturbed molecular vibrational signatures in plasmonic nanocavities Journal Article Light: Science & Applications, 11 (1), pp. 1-9, 2022. @article{Chikkaraddy2022, title = {Mid-infrared-perturbed molecular vibrational signatures in plasmonic nanocavities}, author = {Rohit Chikkaraddy, Angelos Xomalis, Lukas A Jakob, Jeremy J Baumberg}, url = {https://www.nature.com/articles/s41377-022-00709-8}, year = {2022}, date = {2022-00-00}, journal = {Light: Science & Applications}, volume = {11}, number = {1}, pages = {1-9}, abstract = {Recent developments in surface-enhanced Raman scattering (SERS) enable observation of single-bond vibrations in real time at room temperature. By contrast, mid-infrared (MIR) vibrational spectroscopy is limited to inefficient slow detection. Here we develop a new method for MIR sensing using SERS. This method utilizes nanoparticle-on-foil (NPoF) nanocavities supporting both visible and MIR plasmonic hotspots in the same nanogap formed by a monolayer of molecules. Molecular SERS signals from individual NPoF nanocavities are modulated in the presence of MIR photons. The strength of this modulation depends on the MIR wavelength, and is maximized at the 6–12 μm absorption bands of SiO 2 or polystyrene placed under the foil. Using a single-photon lock-in detection scheme we time-resolve the rise and decay of the signal in a few 100 ns. Our observations reveal that the phonon resonances of SiO 2 …}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recent developments in surface-enhanced Raman scattering (SERS) enable observation of single-bond vibrations in real time at room temperature. By contrast, mid-infrared (MIR) vibrational spectroscopy is limited to inefficient slow detection. Here we develop a new method for MIR sensing using SERS. This method utilizes nanoparticle-on-foil (NPoF) nanocavities supporting both visible and MIR plasmonic hotspots in the same nanogap formed by a monolayer of molecules. Molecular SERS signals from individual NPoF nanocavities are modulated in the presence of MIR photons. The strength of this modulation depends on the MIR wavelength, and is maximized at the 6–12 μm absorption bands of SiO 2 or polystyrene placed under the foil. Using a single-photon lock-in detection scheme we time-resolve the rise and decay of the signal in a few 100 ns. Our observations reveal that the phonon resonances of SiO 2 … | |
| 616. | Damiano Barone Alejandro Carnicer Lombarte, Clare Bryant Panagiotis Tourlomousis Russell Hamilton Malwina Prater George Malliaras Kristian Franze Prevention of the foreign body response to implantable medical devices by inflammasome inhibition Journal Article Proceedings of the National Academy of Sciences, 2022. @article{Barone2022, title = {Prevention of the foreign body response to implantable medical devices by inflammasome inhibition}, author = {Damiano Barone, Alejandro Carnicer Lombarte, Clare Bryant, Panagiotis Tourlomousis, Russell Hamilton, Malwina Prater, George Malliaras, Kristian Franze}, url = {https://www.repository.cam.ac.uk/handle/1810/332758}, year = {2022}, date = {2022-00-00}, journal = {Proceedings of the National Academy of Sciences}, keywords = {}, pubstate = {published}, tppubtype = {article} } | |
| 615. | Daniel G Congrave Bluebell Drummond, Qinying Gu Stephanie Montanaro Haydn Francis Victor Riesgo-González Weixuan Zeng Campbell Matthews Simon Dowland Iain Alexander Wright Clare Grey Richard Friend Hugo Bronstein A P Journal of Materials Chemistry C, 2022. @article{Congrave2022, title = {A solution-processable near-infrared thermally activated delayed fluorescent dye with a fused aromatic acceptor and aggregation induced emission behaviour}, author = {Daniel G Congrave, Bluebell Drummond, Qinying Gu, Stephanie Montanaro, Haydn Francis, Victor Riesgo-González, Weixuan Zeng, Campbell Matthews, Simon A Dowland, Iain Alexander Wright, Clare P Grey, Richard Friend, Hugo Bronstein}, url = {https://pubs.rsc.org/en/content/articlehtml/2022/tc/d1tc04753a}, year = {2022}, date = {2022-00-00}, journal = {Journal of Materials Chemistry C}, abstract = {The unique synergy of properties offered by an efficient and processable near-infrared thermally activated delayed fluorescent (NIR TADF) dye could be transformative across research fields. Here, a solution-processable NIR TADF material is demonstrated (CAT-TPE). Good solubility is achieved through the use of a new tetraphenylethylene (TPE)-based triphenylamine electron donor. TADF is confirmed through variable temperature time-resolved measurements at a peak photoluminescence (PL) wavelength of 842 nm in a solution-processed film. An OLED with good roll-off characteristics for solution-processed NIR TADF device is reported with electroluminescence λmax > 700 nm. CAT-TPE also demonstrates classic aggregation induced emission (AIE) behavior, being more emissive when aggregated than in solution with all PL > 700 nm. This work opens the door to the considerably enhanced structural …}, keywords = {}, pubstate = {published}, tppubtype = {article} } The unique synergy of properties offered by an efficient and processable near-infrared thermally activated delayed fluorescent (NIR TADF) dye could be transformative across research fields. Here, a solution-processable NIR TADF material is demonstrated (CAT-TPE). Good solubility is achieved through the use of a new tetraphenylethylene (TPE)-based triphenylamine electron donor. TADF is confirmed through variable temperature time-resolved measurements at a peak photoluminescence (PL) wavelength of 842 nm in a solution-processed film. An OLED with good roll-off characteristics for solution-processed NIR TADF device is reported with electroluminescence λmax > 700 nm. CAT-TPE also demonstrates classic aggregation induced emission (AIE) behavior, being more emissive when aggregated than in solution with all PL > 700 nm. This work opens the door to the considerably enhanced structural … | |
2021 |
||
| 614. |  | Anna B. Gunnarsdóttir Chibueze V. Amanchukwu, Svetlana Menkin ; Grey, Clare P Noninvasive In Situ NMR Study of “Dead Lithium” Formation and Lithium Corrosion in Full-Cell Lithium Metal Batteries Journal Article J. Am. Chem. Soc., 142 (49), pp. 20814–20827, 2021. @article{Gunnarsdóttir2021, title = {Noninvasive In Situ NMR Study of “Dead Lithium” Formation and Lithium Corrosion in Full-Cell Lithium Metal Batteries}, author = {Anna B. Gunnarsdóttir, Chibueze V. Amanchukwu, Svetlana Menkin, and Clare P. Grey}, url = {https://pubs.acs.org/doi/10.1021/jacs.0c10258}, year = {2021}, date = {2021-11-23}, journal = {J. Am. Chem. Soc.}, volume = {142}, number = {49}, pages = {20814–20827}, abstract = {Capacity retention in lithium metal batteries needs to be improved if they are to be commercially viable, the low cycling stability and Li corrosion during storage of lithium metal batteries being even more problematic when there is no excess lithium in the cell. Herein, we develop in situ NMR metrology to study “anode-free” lithium metal batteries where lithium is plated directly onto a bare copper current collector from a LiFePO4 cathode. The methodology allows inactive or “dead lithium” formation during plating and stripping of lithium in a full-cell lithium metal battery to be tracked: dead lithium and SEI formation can be quantified by NMR and their relative rates of formation are here compared in carbonate and ether-electrolytes. Little-to-no dead Li was observed when FEC is used as an additive. The bulk magnetic susceptibility effects arising from the paramagnetic lithium metal were used to distinguish between different surface coverages of lithium deposits. The amount of lithium metal was monitored during rest periods, and lithium metal dissolution (corrosion) was observed in all electrolytes, even during the periods when the battery is not in use, i.e., when no current is flowing, demonstrating that dissolution of lithium remains a critical issue for lithium metal batteries. The high rate of corrosion is attributed to SEI formation on both lithium metal and copper (and Cu+, Cu2+ reduction). Strategies to mitigate the corrosion are explored, the work demonstrating that both polymer coatings and the modification of the copper surface chemistry help to stabilize the lithium metal surface.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Capacity retention in lithium metal batteries needs to be improved if they are to be commercially viable, the low cycling stability and Li corrosion during storage of lithium metal batteries being even more problematic when there is no excess lithium in the cell. Herein, we develop in situ NMR metrology to study “anode-free” lithium metal batteries where lithium is plated directly onto a bare copper current collector from a LiFePO4 cathode. The methodology allows inactive or “dead lithium” formation during plating and stripping of lithium in a full-cell lithium metal battery to be tracked: dead lithium and SEI formation can be quantified by NMR and their relative rates of formation are here compared in carbonate and ether-electrolytes. Little-to-no dead Li was observed when FEC is used as an additive. The bulk magnetic susceptibility effects arising from the paramagnetic lithium metal were used to distinguish between different surface coverages of lithium deposits. The amount of lithium metal was monitored during rest periods, and lithium metal dissolution (corrosion) was observed in all electrolytes, even during the periods when the battery is not in use, i.e., when no current is flowing, demonstrating that dissolution of lithium remains a critical issue for lithium metal batteries. The high rate of corrosion is attributed to SEI formation on both lithium metal and copper (and Cu+, Cu2+ reduction). Strategies to mitigate the corrosion are explored, the work demonstrating that both polymer coatings and the modification of the copper surface chemistry help to stabilize the lithium metal surface. |
| 613. |  | Diana Morzy Roger Rubio-Sánchez, Himanshu Joshi Aleksei Aksimentiev* Lorenzo Di Michele* ; Keyser*, Ulrich F Cations Regulate Membrane Attachment and Functionality of DNA Nanostructures Journal Article American Chemical Society, 2021. @article{Morzy2021, title = {Cations Regulate Membrane Attachment and Functionality of DNA Nanostructures}, author = {Diana Morzy, Roger Rubio-Sánchez, Himanshu Joshi, Aleksei Aksimentiev*, Lorenzo Di Michele*, and Ulrich F. Keyser*}, url = {https://pubs.acs.org/doi/10.1021/jacs.1c00166}, year = {2021}, date = {2021-07-05}, journal = {American Chemical Society}, abstract = {The interplay between nucleic acids and lipids underpins several key processes in molecular biology, synthetic biotechnology, vaccine technology, and nanomedicine. These interactions are often electrostatic in nature, and much of their rich phenomenology remains unexplored in view of the chemical diversity of lipids, the heterogeneity of their phases, and the broad range of relevant solvent conditions. Here we unravel the electrostatic interactions between zwitterionic lipid membranes and DNA nanostructures in the presence of physiologically relevant cations, with the purpose of identifying new routes to program DNA–lipid complexation and membrane-active nanodevices. We demonstrate that this interplay is influenced by both the phase of the lipid membranes and the valency of the ions and observe divalent cation bridging between nucleic acids and gel-phase bilayers. Furthermore, even in the presence of hydrophobic modifications on the DNA, we find that cations are still required to enable DNA adhesion to liquid-phase membranes. We show that the latter mechanism can be exploited to control the degree of attachment of cholesterol-modified DNA nanostructures by modifying their overall hydrophobicity and charge. Besides their biological relevance, the interaction mechanisms we explored hold great practical potential in the design of biomimetic nanodevices, as we show by constructing an ion-regulated DNA-based synthetic enzyme.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The interplay between nucleic acids and lipids underpins several key processes in molecular biology, synthetic biotechnology, vaccine technology, and nanomedicine. These interactions are often electrostatic in nature, and much of their rich phenomenology remains unexplored in view of the chemical diversity of lipids, the heterogeneity of their phases, and the broad range of relevant solvent conditions. Here we unravel the electrostatic interactions between zwitterionic lipid membranes and DNA nanostructures in the presence of physiologically relevant cations, with the purpose of identifying new routes to program DNA–lipid complexation and membrane-active nanodevices. We demonstrate that this interplay is influenced by both the phase of the lipid membranes and the valency of the ions and observe divalent cation bridging between nucleic acids and gel-phase bilayers. Furthermore, even in the presence of hydrophobic modifications on the DNA, we find that cations are still required to enable DNA adhesion to liquid-phase membranes. We show that the latter mechanism can be exploited to control the degree of attachment of cholesterol-modified DNA nanostructures by modifying their overall hydrophobicity and charge. Besides their biological relevance, the interaction mechanisms we explored hold great practical potential in the design of biomimetic nanodevices, as we show by constructing an ion-regulated DNA-based synthetic enzyme. |
| 612. | Kunal M. Patel Stafford Withington, Christopher Thomas N; Goldie, David J Simulation Method for Investigating the Use of Transition-Edge Sensors as Spectroscopic Electron Detectors Journal Article 2021. @article{Patel2021, title = {Simulation Method for Investigating the Use of Transition-Edge Sensors as Spectroscopic Electron Detectors}, author = {Kunal M. Patel, Stafford Withington, Christopher N. Thomas, and David J. Goldie}, url = {https://arxiv.org/pdf/2106.12945.pdf}, year = {2021}, date = {2021-06-25}, abstract = {Transition-edge sensors (TESs) are capable of highly accurate single particle energy measurement. TESs have been used for a wide range of photon detection applications, particularly in astronomy, but very little consideration has been given to their capabilities as electron calorimeters. Existing electron spectrometers require electron filtering optics to achieve energy discrimination, but this step discards the vast majority of electrons entering the instrument. TESs require no such energy filtering, meaning they could provide orders of magnitude improvement in measurement rate. To investigate the capabilities of TESs in electron spectroscopy, a simulation pipeline has been devised. The pipeline allows the results of a simulated experiment to be compared with the actual spectrum of the incident beam, thereby allowing measurement accuracy and efficiency to be studied. Using Fisher information, the energy resolution of the simulated detectors was also calculated, allowing the intrinsic limitations of the detector to be separated from the specific data analysis method used. The simulation platform has been used to compare the performance of TESs with existing X-ray photoelectron spectroscopy (XPS) analysers. TESs cannot match the energy resolution of XPS analysers for high-precision measurements but have comparable or better resolutions for high count rate applications. The measurement rate of a typical XPS analyser can be matched by an array of 10 TESs with 120 µs response times and there is significant scope for improvement, without compromising energy resolution, by increasing array size.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Transition-edge sensors (TESs) are capable of highly accurate single particle energy measurement. TESs have been used for a wide range of photon detection applications, particularly in astronomy, but very little consideration has been given to their capabilities as electron calorimeters. Existing electron spectrometers require electron filtering optics to achieve energy discrimination, but this step discards the vast majority of electrons entering the instrument. TESs require no such energy filtering, meaning they could provide orders of magnitude improvement in measurement rate. To investigate the capabilities of TESs in electron spectroscopy, a simulation pipeline has been devised. The pipeline allows the results of a simulated experiment to be compared with the actual spectrum of the incident beam, thereby allowing measurement accuracy and efficiency to be studied. Using Fisher information, the energy resolution of the simulated detectors was also calculated, allowing the intrinsic limitations of the detector to be separated from the specific data analysis method used. The simulation platform has been used to compare the performance of TESs with existing X-ray photoelectron spectroscopy (XPS) analysers. TESs cannot match the energy resolution of XPS analysers for high-precision measurements but have comparable or better resolutions for high count rate applications. The measurement rate of a typical XPS analyser can be matched by an array of 10 TESs with 120 µs response times and there is significant scope for improvement, without compromising energy resolution, by increasing array size. | |
| 611. |  | Alice J. Merryweather Christoph Schnedermann, Quentin Jacquet Clare Grey & Akshay Rao P Operando optical tracking of single-particle ion dynamics in batteries Journal Article Nature, 594 , pp. 522–528, 2021. @article{Merryweather2021, title = {Operando optical tracking of single-particle ion dynamics in batteries}, author = {Alice J. Merryweather, Christoph Schnedermann, Quentin Jacquet, Clare P. Grey & Akshay Rao}, url = {https://www.nature.com/articles/s41586-021-03584-2}, year = {2021}, date = {2021-06-23}, journal = {Nature}, volume = {594}, pages = {522–528}, abstract = {The key to advancing lithium-ion battery technology—in particular, fast charging—is the ability to follow and understand the dynamic processes occurring in functioning materials under realistic conditions, in real time and on the nano- to mesoscale. Imaging of lithium-ion dynamics during battery operation (operando imaging) at present requires sophisticated synchrotron X-ray1,2,3,4,5,6,7 or electron microscopy8,9 techniques, which do not lend themselves to high-throughput material screening. This limits rapid and rational materials improvements. Here we introduce a simple laboratory-based, optical interferometric scattering microscope10,11,12,13 to resolve nanoscopic lithium-ion dynamics in battery materials, and apply it to follow cycling of individual particles of the archetypal cathode material14,15, LixCoO2, within an electrode matrix. We visualize the insulator-to-metal, solid solution and lithium ordering phase transitions directly and determine rates of lithium diffusion at the single-particle level, identifying different mechanisms on charge and discharge. Finally, we capture the dynamic formation of domain boundaries between different crystal orientations associated with the monoclinic lattice distortion at the Li0.5CoO2 composition16. The high-throughput nature of our methodology allows many particles to be sampled across the entire electrode and in future will enable exploration of the role of dislocations, morphologies and cycling rate on battery degradation. The generality of our imaging concept means that it can be applied to study any battery electrode, and more broadly, systems where the transport of ions is associated with electronic or structural changes. Such systems include nanoionic films, ionic conducting polymers, photocatalytic materials and memristors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The key to advancing lithium-ion battery technology—in particular, fast charging—is the ability to follow and understand the dynamic processes occurring in functioning materials under realistic conditions, in real time and on the nano- to mesoscale. Imaging of lithium-ion dynamics during battery operation (operando imaging) at present requires sophisticated synchrotron X-ray1,2,3,4,5,6,7 or electron microscopy8,9 techniques, which do not lend themselves to high-throughput material screening. This limits rapid and rational materials improvements. Here we introduce a simple laboratory-based, optical interferometric scattering microscope10,11,12,13 to resolve nanoscopic lithium-ion dynamics in battery materials, and apply it to follow cycling of individual particles of the archetypal cathode material14,15, LixCoO2, within an electrode matrix. We visualize the insulator-to-metal, solid solution and lithium ordering phase transitions directly and determine rates of lithium diffusion at the single-particle level, identifying different mechanisms on charge and discharge. Finally, we capture the dynamic formation of domain boundaries between different crystal orientations associated with the monoclinic lattice distortion at the Li0.5CoO2 composition16. The high-throughput nature of our methodology allows many particles to be sampled across the entire electrode and in future will enable exploration of the role of dislocations, morphologies and cycling rate on battery degradation. The generality of our imaging concept means that it can be applied to study any battery electrode, and more broadly, systems where the transport of ions is associated with electronic or structural changes. Such systems include nanoionic films, ionic conducting polymers, photocatalytic materials and memristors. |
| 610. |  | Van De Goor Tim; Liu, Yun; Feldmann Sascha; Bourelle Sean; Neumann Timo; Winkler Thomas; Kelly Nicola; Liu Cheng; Jones Michael; Emge Steffen; Friend Richard; Monserrat Bartomeu; Deschler Felix; Dutton Sian Impact of orientational glass formation and local strain on photo-induced halide segregation in hybrid metal-halide perovskites Journal Article American Chemical Society, 2021, ISSN: 1932-7447. @article{Goor2021, title = {Impact of orientational glass formation and local strain on photo-induced halide segregation in hybrid metal-halide perovskites}, author = {Van De Goor, Tim; Liu, Yun; Feldmann, Sascha; Bourelle, Sean; Neumann, Timo; Winkler, Thomas; Kelly, Nicola; Liu, Cheng; Jones, Michael; Emge, Steffen; Friend, Richard; Monserrat, Bartomeu; Deschler, Felix; Dutton, Sian}, url = {https://pubs.acs.org/doi/10.1021/acs.jpcc.1c03169}, issn = {1932-7447}, year = {2021}, date = {2021-06-17}, journal = {American Chemical Society}, abstract = {Bandgap tuning of hybrid metal-halide perovskites by halide substitution holds promise for tailored light absorption in tandem solar cells and emission in LEDs. However, the impact of halide substitution on the crystal structure and the fundamental mechanism of photo-induced halide segregation remain open questions. Here, using a combination of temperature-dependent X-ray diffraction and calorimetry measurements, we report the emergence of a disorder- and frustration-driven orientational glass for a wide range of compositions in CH3NH3Pb(ClxBr1-x)3. Using temperature-dependent photoluminescence measurements, we find a correlation between halide segregation under illumination and local strains from the orientational glass. We observe no glassy behaviour in CsPb(ClxBr1-x)3, highlighting the importance of A-site cation for the structure and optoelectronic properties. Using first-principles calculations, we identify the local preferential alignment of the organic cations as the glass formation mechanism. Our findings rationalise the superior photostability of mixed-cation metal-halide perovskites and provide guidelines for further stabilisation strategies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bandgap tuning of hybrid metal-halide perovskites by halide substitution holds promise for tailored light absorption in tandem solar cells and emission in LEDs. However, the impact of halide substitution on the crystal structure and the fundamental mechanism of photo-induced halide segregation remain open questions. Here, using a combination of temperature-dependent X-ray diffraction and calorimetry measurements, we report the emergence of a disorder- and frustration-driven orientational glass for a wide range of compositions in CH3NH3Pb(ClxBr1-x)3. Using temperature-dependent photoluminescence measurements, we find a correlation between halide segregation under illumination and local strains from the orientational glass. We observe no glassy behaviour in CsPb(ClxBr1-x)3, highlighting the importance of A-site cation for the structure and optoelectronic properties. Using first-principles calculations, we identify the local preferential alignment of the organic cations as the glass formation mechanism. Our findings rationalise the superior photostability of mixed-cation metal-halide perovskites and provide guidelines for further stabilisation strategies. |
| 609. |  | Sarah Jessl Simon Engelke, Davor Copic Jeremy Baumberg J; Volder, Michael De Anisotropic Carbon Nanotube Structures with High Aspect Ratio Nanopores for Li-Ion Battery Anodes Journal Article ACS Appl. Nano Mater., 2021 , 2021. @article{Jessl2021, title = {Anisotropic Carbon Nanotube Structures with High Aspect Ratio Nanopores for Li-Ion Battery Anodes}, author = {Sarah Jessl, Simon Engelke, Davor Copic, Jeremy J. Baumberg, and Michael De Volder}, url = {https://pubs.acs.org/doi/10.1021/acsanm.1c01157}, year = {2021}, date = {2021-06-16}, journal = {ACS Appl. Nano Mater.}, volume = {2021}, abstract = {Technological advances in membrane technology, catalysis, and electrochemical energy storage require the fabrication of controlled pore structures at ever smaller length scales. It is therefore important to develop processes allowing for the fabrication of materials with controlled submicron porous structures. We propose a combination of colloidal lithography and chemical vapor deposition of carbon nanotubes to create continuous straight pores with diameters down to 100 nm in structures with thicknesses of more than 300 μm. These structures offer unique features, including continuous and parallel pores with aspect ratios in excess of 3000, a low pore tortuosity, good electrical conductivity, and electrochemical stability. We demonstrate that these structures can be used in Li-ion batteries by coating the carbon nanotubes with Si as an active anode material.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Technological advances in membrane technology, catalysis, and electrochemical energy storage require the fabrication of controlled pore structures at ever smaller length scales. It is therefore important to develop processes allowing for the fabrication of materials with controlled submicron porous structures. We propose a combination of colloidal lithography and chemical vapor deposition of carbon nanotubes to create continuous straight pores with diameters down to 100 nm in structures with thicknesses of more than 300 μm. These structures offer unique features, including continuous and parallel pores with aspect ratios in excess of 3000, a low pore tortuosity, good electrical conductivity, and electrochemical stability. We demonstrate that these structures can be used in Li-ion batteries by coating the carbon nanotubes with Si as an active anode material. |
| 608. | Arelo O. A. Tanoh Jack Alexander-Webber, Ye Fan Nicholas Gauriot James Xiao Raj Pandya Zhaojun Li Stephan Hofmann & Akshay Rao Giant photoluminescence enhancement in MoSe2 monolayers treated with oleic acid ligands Journal Article Nanoscale Advances, 3 , pp. 4216-4225, 2021. @article{Tanoh2021, title = {Giant photoluminescence enhancement in MoSe2 monolayers treated with oleic acid ligands}, author = {Arelo O. A. Tanoh, Jack Alexander-Webber, Ye Fan, Nicholas Gauriot, James Xiao, Raj Pandya, Zhaojun Li, Stephan Hofmann & Akshay Rao}, url = {https://pubs.rsc.org/en/content/articlehtml/2021/na/d0na01014f}, year = {2021}, date = {2021-06-12}, journal = {Nanoscale Advances}, volume = {3}, pages = {4216-4225}, abstract = {The inherently low photoluminescence (PL) yields in the as prepared transition metal dichalcogenide (TMD) monolayers are broadly accepted to be the result of atomic vacancies (i.e., defects) and uncontrolled doping, which give rise to non-radiative exciton decay pathways. To date, a number of chemical passivation schemes have been successfully developed to improve PL in sulphur based TMDs i.e., molybdenum disulphide (MoS2) and tungsten disulphide (WS2) monolayers. Studies on solution based chemical passivation schemes for improving PL yields in selenium (Se) based TMDs are however lacking in comparison. Here, we demonstrate that treatment with oleic acid (OA) provides a simple wet chemical passivation method for monolayer MoSe2, enhancing PL yields by an average of 58-fold, while also improving spectral uniformity across the material and reducing the emission linewidth. Excitation intensity dependent PL reveals trap-free PL dynamics dominated by neutral exciton recombination. Time-resolved PL (TRPL) studies reveal significantly increased PL lifetimes, with pump intensity dependent TRPL measurements also confirming trap free PL dynamics in OA treated MoSe2. Field effect transistors show reduced charge trap density and improved on–off ratios after treatment with OA. These results indicate defect passivation by OA, which we hypothesise as ligands passivating chalcogen defects through oleate coordination to Mo dangling bonds. Importantly, this work combined with our previous study on OA treated WS2, verifies OA treatment as a simple solution-based chemical passivation protocol for improving PL yields and electronic characteristics in both selenide and sulphide TMDs – a property that has not been reported previously for other solution-based passivation schemes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The inherently low photoluminescence (PL) yields in the as prepared transition metal dichalcogenide (TMD) monolayers are broadly accepted to be the result of atomic vacancies (i.e., defects) and uncontrolled doping, which give rise to non-radiative exciton decay pathways. To date, a number of chemical passivation schemes have been successfully developed to improve PL in sulphur based TMDs i.e., molybdenum disulphide (MoS2) and tungsten disulphide (WS2) monolayers. Studies on solution based chemical passivation schemes for improving PL yields in selenium (Se) based TMDs are however lacking in comparison. Here, we demonstrate that treatment with oleic acid (OA) provides a simple wet chemical passivation method for monolayer MoSe2, enhancing PL yields by an average of 58-fold, while also improving spectral uniformity across the material and reducing the emission linewidth. Excitation intensity dependent PL reveals trap-free PL dynamics dominated by neutral exciton recombination. Time-resolved PL (TRPL) studies reveal significantly increased PL lifetimes, with pump intensity dependent TRPL measurements also confirming trap free PL dynamics in OA treated MoSe2. Field effect transistors show reduced charge trap density and improved on–off ratios after treatment with OA. These results indicate defect passivation by OA, which we hypothesise as ligands passivating chalcogen defects through oleate coordination to Mo dangling bonds. Importantly, this work combined with our previous study on OA treated WS2, verifies OA treatment as a simple solution-based chemical passivation protocol for improving PL yields and electronic characteristics in both selenide and sulphide TMDs – a property that has not been reported previously for other solution-based passivation schemes. | |
| 607. |  | Ruoqi Ai Christina Boukouvala, George Lewis Hao Wang Han Zhang Yunhe Lai He Huang Emilie Ringe Lei Shao ; Wang, Jianfang Facet- and Gas-Dependent Reshaping of Au Nanoplates by Plasma Treatment Journal Article ACS Nano, 2021. @article{Ai2021, title = {Facet- and Gas-Dependent Reshaping of Au Nanoplates by Plasma Treatment}, author = {Ruoqi Ai, Christina Boukouvala, George Lewis, Hao Wang, Han Zhang, Yunhe Lai, He Huang, Emilie Ringe, Lei Shao, and Jianfang Wang}, url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.1c00861}, year = {2021}, date = {2021-06-11}, journal = {ACS Nano}, abstract = {The reshaping of metal nanocrystals on substrates is usually realized by pulsed laser irradiation or ion-beam milling with complex procedures. In this work, we demonstrate a simple method for reshaping immobilized Au nanoplates through plasma treatment. Au nanoplates can be reshaped gradually with nearly periodic right pyramid arrays formed on the surface of the nanoplates. The gaseous environment in the plasma-treatment system plays a significant role in the reshaping process with only nitrogen-containing environments leading to reshaping. The reshaping phenomenon is facet-dependent, with right pyramids formed only on the exposed {111} facets of the Au nanoplates. The morphological change of the Au nanoplates induced by the plasma treatment leads to large plasmon peak redshifts. The reshaped Au nanoplates possess slightly higher refractive index sensitivities and largely increased surface-enhanced Raman scattering intensities compared to the flat, untreated nanoplates. Our results offer insights for studying the interaction mechanism between plasma and the different facets of noble metal nanocrystals and an approach for reshaping light-interacting noble metal nanocrystals.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The reshaping of metal nanocrystals on substrates is usually realized by pulsed laser irradiation or ion-beam milling with complex procedures. In this work, we demonstrate a simple method for reshaping immobilized Au nanoplates through plasma treatment. Au nanoplates can be reshaped gradually with nearly periodic right pyramid arrays formed on the surface of the nanoplates. The gaseous environment in the plasma-treatment system plays a significant role in the reshaping process with only nitrogen-containing environments leading to reshaping. The reshaping phenomenon is facet-dependent, with right pyramids formed only on the exposed {111} facets of the Au nanoplates. The morphological change of the Au nanoplates induced by the plasma treatment leads to large plasmon peak redshifts. The reshaped Au nanoplates possess slightly higher refractive index sensitivities and largely increased surface-enhanced Raman scattering intensities compared to the flat, untreated nanoplates. Our results offer insights for studying the interaction mechanism between plasma and the different facets of noble metal nanocrystals and an approach for reshaping light-interacting noble metal nanocrystals. |
| 606. |  | AK Jayaram AM Pappa, Ghosh ZA Manzer WC Traberg TPJ Knowles Daniel RM Owens S S Biomembranes in Bioelectronic Sensing Journal Article Trends in Biotechnology, 2021, ISSN: 0167-7799. @article{Jayaram2021, title = {Biomembranes in Bioelectronic Sensing}, author = {AK Jayaram, AM Pappa, S Ghosh, ZA Manzer, WC Traberg, TPJ Knowles, S Daniel, RM Owens}, url = {https://www.sciencedirect.com/science/article/pii/S0167779921001311}, issn = {0167-7799}, year = {2021}, date = {2021-06-10}, journal = {Trends in Biotechnology}, abstract = {Cell membranes are integral to the functioning of the cell and are therefore key to drive fundamental understanding of biological processes for downstream applications. Here we review the current state-of-the art with respect to biomembrane systems and electronic substrates, with a view of how the field has evolved towards creating biomimetic conditions and improving detection sensitivity. Of particular interest are conducting polymers, a class of electroactive polymers, which have the potential to create the next step-change for bioelectronics devices. Lastly, we discuss the impact these types of devices could have for biomedical applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cell membranes are integral to the functioning of the cell and are therefore key to drive fundamental understanding of biological processes for downstream applications. Here we review the current state-of-the art with respect to biomembrane systems and electronic substrates, with a view of how the field has evolved towards creating biomimetic conditions and improving detection sensitivity. Of particular interest are conducting polymers, a class of electroactive polymers, which have the potential to create the next step-change for bioelectronics devices. Lastly, we discuss the impact these types of devices could have for biomedical applications. |
| 605. | ![Structural Origins of Voltage Hysteresis in the Na-ion Cathode P2-Na0.67[Mg0.28Mn0.72]O2: a Combined Spectroscopic and Density Functional Theory Study](https://pubs.acs.org/na101/home/literatum/publisher/achs/journals/content/cmatex/0/cmatex.ahead-of-print/acs.chemmater.1c00248/20210621/images/medium/cm1c00248_0010.gif) | Bassey Euan, Reeves Philip Jones Michael Lee Jeongjae Seymour Ieuan Cibin Giannantonio Grey Clare Chemistry of Materials, 2021. @article{Bassey2021, title = {Structural Origins of Voltage Hysteresis in the Na-ion Cathode P2-Na0.67[Mg0.28Mn0.72]O2: a Combined Spectroscopic and Density Functional Theory Study}, author = {Bassey, Euan, Reeves, Philip, Jones, Michael, Lee, Jeongjae, Seymour, Ieuan, Cibin, Giannantonio, Grey, Clare}, url = {https://pubs.acs.org/doi/10.1021/acs.chemmater.1c00248}, year = {2021}, date = {2021-06-10}, journal = {Chemistry of Materials}, abstract = {P2 layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ XRD, Mn K-edge EXAFS and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle—including the formation of a high-voltage “Z-phase”, an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z-phase is both kinetically and thermodynamically favourable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.}, keywords = {}, pubstate = {published}, tppubtype = {article} } P2 layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ XRD, Mn K-edge EXAFS and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle—including the formation of a high-voltage “Z-phase”, an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z-phase is both kinetically and thermodynamically favourable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility. |
| 604. |  | van de Timo Neumann Sascha Feldmann, Philipp Moser Alex Delhomme Jonathan Zerhoch Tim Goor Shuli Wang Mateusz Dyksik Thomas Winkler Jonathan Finley Paulina Plochocka Martin Brandt Clément Faugeras Andreas Stier & Felix Deschler J S V Nature Communication, 12 (3489 ), 2021. @article{Neumann2021, title = {Manganese doping for enhanced magnetic brightening and circular polarization control of dark excitons in paramagnetic layered hybrid metal-halide perovskites}, author = {Timo Neumann, Sascha Feldmann, Philipp Moser, Alex Delhomme, Jonathan Zerhoch, Tim van de Goor, Shuli Wang, Mateusz Dyksik, Thomas Winkler, Jonathan J. Finley, Paulina Plochocka, Martin S. Brandt, Clément Faugeras, Andreas V. Stier & Felix Deschler}, url = {https://www.nature.com/articles/s41467-021-23602-1}, year = {2021}, date = {2021-06-09}, journal = {Nature Communication}, volume = {12}, number = {3489 }, abstract = {Materials combining semiconductor functionalities with spin control are desired for the advancement of quantum technologies. Here, we study the magneto-optical properties of novel paramagnetic Ruddlesden-Popper hybrid perovskites Mn:(PEA)2PbI4 (PEA = phenethylammonium) and report magnetically brightened excitonic luminescence with strong circular polarization from the interaction with isolated Mn2+ ions. Using a combination of superconducting quantum interference device (SQUID) magnetometry, magneto-absorption and transient optical spectroscopy, we find that a dark exciton population is brightened by state mixing with the bright excitons in the presence of a magnetic field. Unexpectedly, the circular polarization of the dark exciton luminescence follows the Brillouin-shaped magnetization with a saturation polarization of 13% at 4 K and 6 T. From high-field transient magneto-luminescence we attribute our observations to spin-dependent exciton dynamics at early times after excitation, with first indications for a Mn-mediated spin-flip process. Our findings demonstrate manganese doping as a powerful approach to control excitonic spin physics in Ruddlesden-Popper perovskites, which will stimulate research on this highly tuneable material platform with promise for tailored interactions between magnetic moments and excitonic states.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Materials combining semiconductor functionalities with spin control are desired for the advancement of quantum technologies. Here, we study the magneto-optical properties of novel paramagnetic Ruddlesden-Popper hybrid perovskites Mn:(PEA)2PbI4 (PEA = phenethylammonium) and report magnetically brightened excitonic luminescence with strong circular polarization from the interaction with isolated Mn2+ ions. Using a combination of superconducting quantum interference device (SQUID) magnetometry, magneto-absorption and transient optical spectroscopy, we find that a dark exciton population is brightened by state mixing with the bright excitons in the presence of a magnetic field. Unexpectedly, the circular polarization of the dark exciton luminescence follows the Brillouin-shaped magnetization with a saturation polarization of 13% at 4 K and 6 T. From high-field transient magneto-luminescence we attribute our observations to spin-dependent exciton dynamics at early times after excitation, with first indications for a Mn-mediated spin-flip process. Our findings demonstrate manganese doping as a powerful approach to control excitonic spin physics in Ruddlesden-Popper perovskites, which will stimulate research on this highly tuneable material platform with promise for tailored interactions between magnetic moments and excitonic states. |
| 603. |  | de Junyang Huang David-Benjamin Grys, Jack Griffiths Bart Nijs Marlous Kamp Qianqi Lin ; Baumberg, Jeremy J Tracking interfacial single-molecule pH and binding dynamics via vibrational spectroscopy Journal Article Science Advances, 7 (23), 2021. @article{Huang2021, title = {Tracking interfacial single-molecule pH and binding dynamics via vibrational spectroscopy}, author = {Junyang Huang, David-Benjamin Grys, Jack Griffiths, Bart de Nijs, Marlous Kamp, Qianqi Lin and Jeremy J. Baumberg}, url = {https://advances.sciencemag.org/content/7/23/eabg1790}, year = {2021}, date = {2021-06-04}, journal = {Science Advances}, volume = {7}, number = {23}, abstract = {Understanding single-molecule chemical dynamics of surface ligands is of critical importance to reveal their individual pathways and, hence, roles in catalysis, which ensemble measurements cannot see. Here, we use a cascaded nano-optics approach that provides sufficient enhancement to enable direct tracking of chemical trajectories of single surface-bound molecules via vibrational spectroscopy. Atomic protrusions are laser-induced within plasmonic nanojunctions to concentrate light to atomic length scales, optically isolating individual molecules. By stabilizing these atomic sites, we unveil single-molecule deprotonation and binding dynamics under ambient conditions. High-speed field-enhanced spectroscopy allows us to monitor chemical switching of a single carboxylic group between three discrete states. Combining this with theoretical calculation identifies reversible proton transfer dynamics (yielding effective single-molecule pH) and switching between molecule-metal coordination states, where the exact chemical pathway depends on the intitial protonation state. These findings open new domains to explore interfacial single-molecule mechanisms and optical manipulation of their reaction pathways.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding single-molecule chemical dynamics of surface ligands is of critical importance to reveal their individual pathways and, hence, roles in catalysis, which ensemble measurements cannot see. Here, we use a cascaded nano-optics approach that provides sufficient enhancement to enable direct tracking of chemical trajectories of single surface-bound molecules via vibrational spectroscopy. Atomic protrusions are laser-induced within plasmonic nanojunctions to concentrate light to atomic length scales, optically isolating individual molecules. By stabilizing these atomic sites, we unveil single-molecule deprotonation and binding dynamics under ambient conditions. High-speed field-enhanced spectroscopy allows us to monitor chemical switching of a single carboxylic group between three discrete states. Combining this with theoretical calculation identifies reversible proton transfer dynamics (yielding effective single-molecule pH) and switching between molecule-metal coordination states, where the exact chemical pathway depends on the intitial protonation state. These findings open new domains to explore interfacial single-molecule mechanisms and optical manipulation of their reaction pathways. |