The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confine...The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confined interface in PBXs,bilayer films of F2314/HMX and F2311/HMX were designed.Neutron reflectivity(NR),nanoindentation,and X-ray reflectivity(XRR)were employed to examine the layer thickness,interface characteristics,diffusion behavior,and surface morphology of the bilayers.NR measurements revealed interface thicknesses of 45Å and 98Å for F2314/HMX and F2311/HMX,respectively,indicating deeper penetration of F2311 into the HMX matrix.NR also suggested a denser polymer network with a higher scattering length density(SLD)near the HMX interface for both fluoroelastomers,while the bound layer of F2311 was notably thicker.Nanoindentation cross-checks and confirms the presence of a bound layer,highlighting the differences in stiffness and diffusion ability between the two polymers.The consistency between the NR and nanoindentation results suggests that F2311 demonstrates better flexibility and elasticity,whereas F2314 is stiffer and more plastic.Accordingly,the structures and performances of different fluoroelastomers at the HMX interface are discussed,which can provide valuable insights into the selection of binders for PBX formulations tailored to specific applications.展开更多
The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the inter...The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the interlayer coupling and switching mechanisms in YIG/Py(permalloy)heterostructures based on gadolinium gallium garnet(GGG)and SiO_(2)substrates.We observe antiferromagnetic interlayer coupling between Py and YIG on SiO_(2)substrates,whereas ferromagnetic interlayer coupling is observed on GGG substrates.Using polarized neutron reflectometry with depth-and elementresolved measurements,we obtain an in-depth understanding of the magnetic interactions between the YIG and Py layers.We demonstrate that polycrystalline YIG gives rise to antiferromagnetic interlayer coupling.This work provides valuable insights into designing and controlling magnetic coupling in hybrid structures for spintronic applications.展开更多
Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))has been attracting more and more attention due to its unique merits such as wide bandgap(∼4.9 eV),low growth temperature,large-scale uniformity,low cost and energy efficient,makin...Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))has been attracting more and more attention due to its unique merits such as wide bandgap(∼4.9 eV),low growth temperature,large-scale uniformity,low cost and energy efficient,making it a powerful competitor in flexible deep ultraviolet(UV)photodetection.Although the responsivity of the ever-reported a-Ga_(2)O_(3)UV photodetectors(PDs)is usually in the level of hundreds of A/W,it is often accompanied by a large dark current due to the presence of abundant oxygen vacancy(VO)defects,which severely limits the possibility to detect weak signals and achieve versatile applications.In this work,the VO defects in a-Ga_(2)O_(3)thin films are successfully passivated by in-situ hydrogen doping during the magnetron sputtering process.As a result,the dark current of a-Ga_(2)O_(3)UV PD is remarkably suppressed to 5.17×10^(-11) A at a bias of 5 V.Importantly,the photocurrent of the corresponding device is still as high as 1.37×10^(-3)A,leading to a high photo-to-dark current ratio of 2.65×107 and the capability to detect the UV light with the intensity below 10 nW cm^(-2).Moreover,the H-doped a-Ga_(2)O_(3)thin films have also been deposited on polyethylene naphtholate substrates to construct flexible UV PDs,which exhibit no great degradation in bending states and fatigue tests.These results demonstrate that hydrogen doping can effectively improve the performance of a-Ga_(2)O_(3)UV PDs,further promoting its practical application in various areas.展开更多
As phase separation between the small-molecule semiconductor and the polymer binder is the key enabler of blend-based organic field-effect transistors(OFETs)fabricated by low-cost solution processing,it is crucial to ...As phase separation between the small-molecule semiconductor and the polymer binder is the key enabler of blend-based organic field-effect transistors(OFETs)fabricated by low-cost solution processing,it is crucial to understand the underlying phase separation mechanisms that determine the phase morphology,which significantly impacts device performance.Beyond the parameter space investigated in previous work,here we investigate the formation of blends by varying the branch architecture of the polymer binder and by shortening the solvent dry time using ultrasonic spray casting.The phase morphologies of the resulting blend films have been thoroughly characterized with a variety of techniques in three dimensions over multiple length scales,including AFM,energy-filtered transmission electron microscope,and neutron reflectivity,and have been correlated with electrical transport performance.From the results,we have inferred that the phase morphology is kinetically determined,limited by the inherent slow movement of polymer macromolecules.The kinetic picture,supported by molecular dynamics modeling,not only consistently explains our observations but also resolves inconsistencies in previous works.The achieved mechanistic understanding will guide further optimization of blend-based organic electronics,such as OFETs and organic photovoltaics.展开更多
We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substr...We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.展开更多
Atomic layer deposition(ALD)has been an important surface processing technique of materials of important applications.In the present investigation aluminum oxide thin films are generated using ALD technique(ALD-Al_(2)...Atomic layer deposition(ALD)has been an important surface processing technique of materials of important applications.In the present investigation aluminum oxide thin films are generated using ALD technique(ALD-Al_(2)O_(3)).The ALD-Al_(2)O_(3)films are formed over SS304 substrates with thicknesses of 20,75 and 100 nm and the corrosion investigations are carried out using polarization and impedance measurements.The neutron reflectivity measurements are carried out to measure the thickness and surface roughness of the film.The corrosion property of SS304 observed to be reduced on ALD deposition which has been evident from the polarization measurements and supported by the electrochemical impedance measurements.The ennoblement in the corrosion potential has been observed due to the ALD-Al_(2)O_(3)film formation over the SS304 surface.The polarization resistance remained high even at high applied anodic potential of 0.7 V,the protection remained stable even at an elevated temperature of 60οC.The investigation supports the primary objective of the important role of the protection of material through thin ALD-Al_(2)O_(3)protective films.展开更多
Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics,especially utilizing organic photovoltaics(OPVs).Combined liquid‐and solid...Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics,especially utilizing organic photovoltaics(OPVs).Combined liquid‐and solid‐state processing,such as printing and lamination used in industry for developing indoor OPVs,also provides a new opportunity to investigate the device structure,which is otherwise hardly possible based on the conventional approach due to solvent orthogonality.This study investigates the impact of fullerene‐based acceptor interlayer on the performance of conjugated polymer–fullerene‐based laminated OPVs for indoor applications.We observe open‐circuit voltage(VOC)loss across the interface despite this arrangement being presumed to be ideal for optimal device performance.Incorporating insulating organic components such as polyethyleneimine(PEI)or polystyrene(PS)into fullerene interlayers decreases the work function of the cathode,leading to better energy level alignment with the active layer(AL)and reducing the VOC loss across the interface.Neutron reflectivity studies further uncover two different mechanisms behind the VOC increase upon the incorporation of these insulating organic components.The self‐organized PEI layer could hinder the transfer of holes from the AL to the acceptor interlayer,while the gradient distribution of the PS‐incorporated fullerene interlayer eliminates the thermalization losses.This work highlights the importance of structural dynamics near the extraction interfaces in OPVs and provides experimental demonstrations of interface investigation between solution‐processed cathodic fullerene layer and bulk heterojunction AL.展开更多
基金supported in part by the National Natural Science Foundation of China(Nos.12335018,12105264,and 12275248)NSAF Joint Fund Project(Nos.U2230107,U1730244,U2130207)+1 种基金Innovation and Development Fund of China Academy of Engineering Physics(No.CXKS20240052)Central Guidance for Local Science and Technology Development Fund Project(No.2023ZYDF075).
文摘The current work addresses the challenge of elucidating the performance of fluoroelastomers within the HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)based polymer-bonded explosives(PBXs).To simulate the confined interface in PBXs,bilayer films of F2314/HMX and F2311/HMX were designed.Neutron reflectivity(NR),nanoindentation,and X-ray reflectivity(XRR)were employed to examine the layer thickness,interface characteristics,diffusion behavior,and surface morphology of the bilayers.NR measurements revealed interface thicknesses of 45Å and 98Å for F2314/HMX and F2311/HMX,respectively,indicating deeper penetration of F2311 into the HMX matrix.NR also suggested a denser polymer network with a higher scattering length density(SLD)near the HMX interface for both fluoroelastomers,while the bound layer of F2311 was notably thicker.Nanoindentation cross-checks and confirms the presence of a bound layer,highlighting the differences in stiffness and diffusion ability between the two polymers.The consistency between the NR and nanoindentation results suggests that F2311 demonstrates better flexibility and elasticity,whereas F2314 is stiffer and more plastic.Accordingly,the structures and performances of different fluoroelastomers at the HMX interface are discussed,which can provide valuable insights into the selection of binders for PBX formulations tailored to specific applications.
基金supported by the National Key Basic Research Program of China(Grant Nos.2021YFA1400300 and 2023YFA1610400)the National Natural Science Foundation of China(Grant Nos.12204268,52371169,52130103,and U22A20263)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023B1515120015)the Open Research Fund of Songshan Lake Materials Laboratory(Grant No.2022SLABFN13)。
文摘The complex interplay of magnetic interactions at the yttrium iron garnet(YIG)/ferromagnet interface is important for spintronic and magnonic devices.In this study,we present a comprehensive investigation of the interlayer coupling and switching mechanisms in YIG/Py(permalloy)heterostructures based on gadolinium gallium garnet(GGG)and SiO_(2)substrates.We observe antiferromagnetic interlayer coupling between Py and YIG on SiO_(2)substrates,whereas ferromagnetic interlayer coupling is observed on GGG substrates.Using polarized neutron reflectometry with depth-and elementresolved measurements,we obtain an in-depth understanding of the magnetic interactions between the YIG and Py layers.We demonstrate that polycrystalline YIG gives rise to antiferromagnetic interlayer coupling.This work provides valuable insights into designing and controlling magnetic coupling in hybrid structures for spintronic applications.
基金supported by Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2022A1515110607 and 2019B1515120057)the National Natural Science Foundation of China(Grant Nos.62174113,12174275,61874139,61904201 and 11875088).
文摘Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))has been attracting more and more attention due to its unique merits such as wide bandgap(∼4.9 eV),low growth temperature,large-scale uniformity,low cost and energy efficient,making it a powerful competitor in flexible deep ultraviolet(UV)photodetection.Although the responsivity of the ever-reported a-Ga_(2)O_(3)UV photodetectors(PDs)is usually in the level of hundreds of A/W,it is often accompanied by a large dark current due to the presence of abundant oxygen vacancy(VO)defects,which severely limits the possibility to detect weak signals and achieve versatile applications.In this work,the VO defects in a-Ga_(2)O_(3)thin films are successfully passivated by in-situ hydrogen doping during the magnetron sputtering process.As a result,the dark current of a-Ga_(2)O_(3)UV PD is remarkably suppressed to 5.17×10^(-11) A at a bias of 5 V.Importantly,the photocurrent of the corresponding device is still as high as 1.37×10^(-3)A,leading to a high photo-to-dark current ratio of 2.65×107 and the capability to detect the UV light with the intensity below 10 nW cm^(-2).Moreover,the H-doped a-Ga_(2)O_(3)thin films have also been deposited on polyethylene naphtholate substrates to construct flexible UV PDs,which exhibit no great degradation in bending states and fatigue tests.These results demonstrate that hydrogen doping can effectively improve the performance of a-Ga_(2)O_(3)UV PDs,further promoting its practical application in various areas.
文摘As phase separation between the small-molecule semiconductor and the polymer binder is the key enabler of blend-based organic field-effect transistors(OFETs)fabricated by low-cost solution processing,it is crucial to understand the underlying phase separation mechanisms that determine the phase morphology,which significantly impacts device performance.Beyond the parameter space investigated in previous work,here we investigate the formation of blends by varying the branch architecture of the polymer binder and by shortening the solvent dry time using ultrasonic spray casting.The phase morphologies of the resulting blend films have been thoroughly characterized with a variety of techniques in three dimensions over multiple length scales,including AFM,energy-filtered transmission electron microscope,and neutron reflectivity,and have been correlated with electrical transport performance.From the results,we have inferred that the phase morphology is kinetically determined,limited by the inherent slow movement of polymer macromolecules.The kinetic picture,supported by molecular dynamics modeling,not only consistently explains our observations but also resolves inconsistencies in previous works.The achieved mechanistic understanding will guide further optimization of blend-based organic electronics,such as OFETs and organic photovoltaics.
文摘We present measurements of the in situ, microscopic architecture of a self- assembled bilayer at the interface between a regularly nanopatterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nanoscale holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this stud; 1,2-dilauroyl-sn-glycero-3-phosphocholine （DLPC） single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion （VF） or by the Langmuir-Schaefer （L-S） technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nanopatterned features.
文摘Atomic layer deposition(ALD)has been an important surface processing technique of materials of important applications.In the present investigation aluminum oxide thin films are generated using ALD technique(ALD-Al_(2)O_(3)).The ALD-Al_(2)O_(3)films are formed over SS304 substrates with thicknesses of 20,75 and 100 nm and the corrosion investigations are carried out using polarization and impedance measurements.The neutron reflectivity measurements are carried out to measure the thickness and surface roughness of the film.The corrosion property of SS304 observed to be reduced on ALD deposition which has been evident from the polarization measurements and supported by the electrochemical impedance measurements.The ennoblement in the corrosion potential has been observed due to the ALD-Al_(2)O_(3)film formation over the SS304 surface.The polarization resistance remained high even at high applied anodic potential of 0.7 V,the protection remained stable even at an elevated temperature of 60οC.The investigation supports the primary objective of the important role of the protection of material through thin ALD-Al_(2)O_(3)protective films.
基金G.B.,J.B.,and F.G.acknowledge the Swedish Foundation for Strategic Research(SSF)(No.ID20‐0105)A.Z.and F.E.acknowledge the Swedish Research Council(LiU No.201900653)for financial support.
文摘Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics,especially utilizing organic photovoltaics(OPVs).Combined liquid‐and solid‐state processing,such as printing and lamination used in industry for developing indoor OPVs,also provides a new opportunity to investigate the device structure,which is otherwise hardly possible based on the conventional approach due to solvent orthogonality.This study investigates the impact of fullerene‐based acceptor interlayer on the performance of conjugated polymer–fullerene‐based laminated OPVs for indoor applications.We observe open‐circuit voltage(VOC)loss across the interface despite this arrangement being presumed to be ideal for optimal device performance.Incorporating insulating organic components such as polyethyleneimine(PEI)or polystyrene(PS)into fullerene interlayers decreases the work function of the cathode,leading to better energy level alignment with the active layer(AL)and reducing the VOC loss across the interface.Neutron reflectivity studies further uncover two different mechanisms behind the VOC increase upon the incorporation of these insulating organic components.The self‐organized PEI layer could hinder the transfer of holes from the AL to the acceptor interlayer,while the gradient distribution of the PS‐incorporated fullerene interlayer eliminates the thermalization losses.This work highlights the importance of structural dynamics near the extraction interfaces in OPVs and provides experimental demonstrations of interface investigation between solution‐processed cathodic fullerene layer and bulk heterojunction AL.
