Optofluidics:the interaction between light and flowing liquids in integrated devices

Optofluidics is a rising technology that combines microfluidics and optics.Its goal is to manipulate light and flowing liquids on the micro/nanoscale and exploiting their interaction in optofluidic chips.The fluid flow in the on-chip devices is reconfigurable,non-uniform and usually transports substances being analyzed,offering a new idea in the accurate manipulation of lights and biochemical samples.In this paper,we summarized the light modulation in heterogeneous media by unique fluid dynamic properties such as molecular diffusion,heat conduction,centrifugation effect,light-matter interaction and others.By understanding the novel phenomena due to the interaction of light and flowing liquids,quantities of tunable and reconfigurable optofluidic devices such as waveguides,lenses,and lasers are introduced.Those novel applications bring us firm conviction that optofluidics would provide better solutions to high-efficient and high-quality lab-on-chip systems in terms of biochemical analysis and environment monitoring.

To what extent of ion neutralization can multivalent ion distributions around RNA-like macroions be described by Poisson-Boltzmann theory?

Nucleic acids are negatively charged biomolecules, and metal ions in solutions are important to their folding structures and thermodynamics, especially multivalent ions. However, it has been suggested that the binding of multivalent ions to nucleic acids cannot be quantitatively described by the well-established Poisson-Boltzmann （PB） theory. In this work, we made extensive calculations of ion distributions around various RNA-like macroions in divalent and trivalent salt solutions by PB theory and Monte Carlo （MC） simulations. Our calculations show that PB theory appears to underestimate multi- valent ion distributions around RNA-like macroions while can reliably predict monovalent ion distributions. Our extensive comparisons between PB theory and MC simulations indicate that when an RNA-like macroion gets ion neutralization be- yond a ＂critical＂ value, the multivalent ion distribution around that macroion can be approximately described by PB theory. Furthermore, an empirical formula was obtained to approximately quantify the critical ion neutralization for various RNA- like macroions in multivalent salt solutions, and this empirical formula was shown to work well for various real nucleic acids including RNAs and DNAs.

Low-Temperature Growing Anatase TiO2/SnO2 Multi-dimensional Heterojunctions at MXene Conductive Network for High-Efficient Perovskite Solar Cells

A multi-dimensional conductive heterojunction structure,composited by TiO2,SnO2,and Ti3C2TX MXene,is facilely designed and applied as electron transport layer in efficient and stable planar perovskite solar cells.Based on an oxygen vacancy scramble effect,the zero-dimensional anatase TiO2 quantum dots,surrounding on two-dimensional conductive Ti3C2TX sheets,are in situ rooted on three-dimensional SnO2 nanoparticles,constructing nanoscale TiO2/SnO2 heterojunctions.The fabrication is implemented in a controlled lowtemperature anneal method in air and then in N2 atmospheres.With the optimal MXene content,the optical property,the crystallinity of perovskite layer,and internal interfaces are all facilitated,contributing more amount of carrier with effective and rapid transferring in device.The champion power conversion efficiency of resultant perovskite solar cells achieves 19.14%,yet that of counterpart is just 16.83%.In addition,it can also maintain almost 85%of its initial performance for more than 45 days in 30–40%humidity air;comparatively,the counterpart declines to just below 75%of its initial performance.

Performance optimization of dye-sensitized solar cells by gradient-ascent architecture of SiO_2@Au@TiO_2 microspheres embedded with Au nanoparticles

Highly homogeneous, well dispersed SiO_2@Au@TiO_2(SAT) microspheres decorated with Au nanoparticles(AuNPs) were prepared and incorporated into the photoanode with an optimized concentration gradientascent. The effects of SAT microspheres and the gradient-ascent architecture on the light absorption and the photoelectric conversion efficiency(PCE) of the dye-sensitized solar cells(DSSCs) were investigated.Studies indicate that the introduction of SAT microspheres and the gradient-ascent architecture in the photoanode significantly enhance the light scattering and harvesting capability of the photoanode. The DSSC with the optimized SAT gradient-ascent photoanode has the maximum short circuit current density(J_(sc)) of 17.7 mA cm^(-2) and PCE of 7.75%, remarkably higher than those of the conventional DSSC by 23.7%and 28.0%, respectively. This significantly enhancement of the performance of the DSSC can be attributed to the excellent light reflection/scattering of SAT, the localized surface plasma resonance(LSPR) effect of AuNPs within the microspheres, and the gradient-ascent architecture of SAT microspheres inside the photoanode. This study demonstrates that the tri-synergies of the scattering of SAT microspheres, the LSPR of AuNPs and the gradient-ascent architecture can effectively improve the PCE of DSSC.

Antimony Potassium Tartrate Stabilizes Wide-Bandgap Perovskites for Inverted 4-T All-Perovskite Tandem Solar Cells with Efficiencies over 26%

Wide-bandgap(WBG)perovskites have been attracting much attention because of their immense potential as a front light-absorber for tandem solar cells.However,WBG perovskite solar cells(PSCs)generally exhibit undesired large open-circuit voltage(VOC)loss due to light-induced phase segregation and severe non-radiative recombination loss.Herein,antimony potassium tartrate(APTA)is added to perovskite precursor as a multifunctional additive that not only coordinates with unbonded lead but also inhibits the migration of halogen in perovskite,which results in suppressed non-radiative recombination,inhibited phase segregation and better band energy alignment.Therefore,a APTA auxiliary WBG PSC with a champion photoelectric conversion efficiency of 20.35%and less hysteresis is presented.They maintain 80%of their initial efficiencies under 100 mW cm^(-2)white light illumination in nitrogen after 1,000 h.Furthermore,by combining a semi-transparent WBG perovskite front cell with a narrow-bandgap tin–lead PSC,a perovskite/perovskite four-terminal tandem solar cell with an efficiency over 26%is achieved.Our work provides a feasible approach for the fabrication of efficient tandem solar cells.

Copper ion beam emission in solid electrolyte Rb_(4)Cu_(16)I_(6.5)Cl_(13.5)

Copper ion conducting solid electrolyte Rb_(4)Cu_(16)I_(6.5)Cl_(13.5)was prepared by means of mechano-chemical method.The structure and morphology of the powder was investigated by x-ray diffraction and scanning electron microscopy.The grain size was estimated to be 0.2-0.9μm and the ionic conductivity at room temperature was approximately 0.206 S/cm.The solid electrolyte Rb_(4)Cu_(16)I_(6.5)Cl_(13.5)was exploited for copper ion beam generation.The copper ion emission current of several nA was successfully obtained at acceleration voltages of 15 kV and temperature of 197℃in vacuum of 2.1×10^(-4)Pa.A good linear correlation between the logarithmic ion current(logI)and the square root of the acceleration voltage(U_(acc))at high voltage range was obtained,suggesting the Schottky emission mechanism in the process of copper ion beam generation.

Intrinsically large effective mass and multi-valley band characteristics of n-type Bi_(2)eBi_(2)Te_(3)superlattice-like films

Thermoelectric superlattices are expected to decouple the strong correlation between various thermo-electric parameters,and are an important strategy for excellent thermoelectric performances.The superlattices of(Bi_(2))m(Bi_(2)Te_(3))n homologous series are well-known for low lattice thermal conductivity and intriguing topological surface states.However,the impacts of electronic structure on the thermo-electric performance were still not well-understood in(Bi_(2))m(Bi_(2)Te_(3))n.To cope with this issue,Bi_(2)eBi_(2)Te_(3)superlattice-like films with adjustable Bi_(2)/(Bi_(2)+Bi_(2)Te_(3))molar ratio(R)were successfully fabricated by the molecular beam epitaxy technique.Angle-resolved photoemission spectroscopy measurements com-bined with theoretical calculations revealed the conduction band evolution from single-valley to multi-valley as R≥0.30,leading to intrinsically high carrier effective mass and improved thermoelectric power factor.Also,the superlattice film(R=0.46)with the structure close to Bi_(4)Te_(3)possesses the topological surface state feature around the high symmetry point.As a result of the high effective mass of 3.9 m0 and very high electron density of_(2).31×10^(21)cm^(-3),the film with R=0.46 acquired the highest power factor of 1.49 mW·m^(-1)·K^(-2)at 420 K,outperforming that of other(Bi_(2))m(Bi_(2)Te_(3))n superlattices.This work lays an essential foundation on understanding the electronic structure and further improving thermoelectric performances of(Bi_(2))m(Bi_(2)Te_(3))n homologous series.

Constructing ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on Cu doped CoZn-ZIF derived porous N-doped carbon for highly efficient dehydrogenation of ammonia borane

Rational construction of highly dispersed,small size,low cost catalysts for release of hydrogen from ammonia borane(AB)is regarded as a prospective approach for promoting the development of upcoming hydrogen economy.However,the high price and scarcity of precious metal catalysts impose restrictions on their large-scale application.To this end,with the aid of a Cu doped CoZn-zeolitic imidazolate frameworks(ZIFs)template strategy,we successfully construct ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on CoZn-ZIF derived porous N-doped carbon(Co_(2)P/(0.59-Cu_(3)P)-NC)as an efficient non-noble-metal catalyst.Specifically,Co and Cu atoms can be geometrically separated to high degree due to the presence of Zn in the CuCoZn-ZIF precursor,evaporation of Zn during pyrolysis can generate porous structure with the framework well maintained.The results show that porous Co_(2)P/(0.59-Cu_(3)P)-NC bimetallic phosphide exhibits large specific surface area,hierarchical pore structure,well-exposed active sites.Based on the kinetics analyses and ion effects,the catalyst has achieved an unprecedentedly high total turnover frequency(TOF)of 798 mol·molcat^(−1)·min^(−1)in 0.4 M NaOH solution at 298 K,which surpasses all the ever-reported transition-metal phosphides catalysts for hydrogen generation from AB.Experiments and theoretical studies confirm that the highly porous structure of the support,the ultrafine and high dispersion of nanoparticles,the N/P doping and their synergistic effects(e.g.,M-P,M-N,N-C,M-M',M-support)jointly induce strong electron transfer,which can reduce the reaction energy barrier and enhance their interaction with AB,thus correspondingly obtaining excellent catalytic performance.The mechanism and strategy presented in this work pave an avenue for the design of non-noble metal catalyst for hydrogen energy system.

Enhanced efficiency and stability of triple-cation perovskite solar cells with CsPbI_(x)Br_(3−x)QDs“surface patches”

Perovskite solar cells(PSCs)with a light-harvesting three-dimensional perovskite bulk layer as backbone component have achieved great progress in performance.Nonradiative recombination is one major place to improve efficiency and stability as they cause significant energy loss in PSCs.Additionally,an imperfection in grain boundaries will initiate device degradation.One of the most successful strategies to decrease nonradiative recombination in PSCs is the introduction of reduced dimensional perovskite(e.g.,perovskite quantum wells),benefiting the device's efficiency and stability tremendously.Here,instead of quantum wells,mixed-cation perovskites with ligand-contained CsPbBr_(x)I_(3−x)quantum dots(QDs)are prepared,which is shown to function as perovskite healing“surface patches.”Benefiting from the“surface patches”effect,the QDs-film shows reduced defects and enhancing film quality which lead to the excellent performance of solar cells(enhancing the power conversion efficiency from 19.21%of the control device to 21.71%[22.1%in reverse scan]).

Intermediate phase assisted sequential deposition of reverse-graded quasi-2D alternating cation perovskites for MA-free perovskite solar cells

One-step deposition approaches have been widely applied and developed in the fabrication of quasi-2D perovskites.However,the regulation of quantum wells(QWs)and crystalline orientation is difficult and complicated when using this methodology.Sequential deposition is another widespread synthetic approach for preparing perovskite films and perovskite dimension engineering.In this article,δ-CsPbI_(3)intermediate phase assisted sequential(IPAS)deposition is successfully carried out to fabricate MA-free quasi-2D ACI perovskites.The amount of theδ-CsPbI_(3)intermediate phase in the PbI2 layer and the concentration of GAI molecule in the IPA solution both play important roles in the production of MA-free quasi-2D ACI perovskite films.The n value of the MA-free quasi-2D ACI perovskites can be adjusted,which affects the photovoltaic performance and device stability.Compared with one-step deposition,the MA-free quasi-2D ACI perovskites prepared via IPAS deposition have opposite reverse-graded QW distribution and improved vertical orientation,leading to a remarkable PEC of up to 18.86%and allowing the preparation of unpackaged devices with prominent working stability(80%,400 h).The underlying mechanism and crystallization pathway of IPAS deposition confirm that sequential deposition has unique superiority in regulating the QW distribution and crystalline orientation of quasi-2D perovskites.

Influences of the Shape of Magnetic Material on the Magnetoelectric Properties of the PZT/Metglas Composite

In this paper,the influences of the shape of magnetic material on the magnetoelectric（ME）properties of PZT/Metglas magnetoelectric（ME）composites have been investigated.The results indicate that,with the decrease of the waist length（L w）of the dumbbell-shaped Metglas,the magnetic flux density in the center region and ME coefficients（αME）of the composites increase,while the optimal bias magnetic field H dc decreases on the contrary.In an AC magnetic field of 1 k Hz,the maximumαME（αMax）of the composite with L w=20 mm exhibits 1.3 times larger than that of the one with L w=50 mm,and the optimal H dc deceases by 15%.At the resonant frequencies of each composites,αMax is enhanced by1.3 times as L w decreases from 50 to 20 mm.The simulation made by Comsol Multiphysics and the theoretical analysis based on an equivalent magnetic circuit confirm the experimental results.

Lattice Thermal Conductivity of Boron Nitride Nanoribbon from Molecular Dynamics Simulation

The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used to acquire the thermal conductivity from heat current auto-correlation function（HCACF）. HCACF of the selected BNNR system shows a tendency of a very fast decay and then be followed by a very slow decay process,finally,approaching zero approximately within 3 ps. The convergence of lattice thermal conductivity demonstrates that the thermal conductivity of BNNR can be simulated by EMD simulation using several thousands of atoms with periodic boundary conditions. The results show that BNNR exhibit lower thermal conductivity than that of boron nitride（BN） monolayer,which indicates that phonons boundary scatting significantly suppresses the phonons transport in BNNR. Vacancies in BNNR greatly affect the lattice thermal conductivity,in detail,only 1% concentration of vacancies in BNNR induce a 60% reduction of the lattice thermal conductivity at room temperature.

Enhancement of Magnetoelectric Properties in A Surface-Mount Magnetoelectric Device

The fabrication and properties of a novel double layered surface-mount magnetoelectric（ME） device are investigated and reported. This ME device is made up of two opposite polarized piezoelectric PZT slices bonded on the same side of a magnetostrictive material Metglas, forming a novel two PZT in-series device. ME voltage obtained from the two PZT in-series is obviously higher than that of single PZT in a magnetic field with certain value. The ME voltage coefficient（αV） of the surface-mount ME device is significantly enhanced by adjusting the thickness of Metglas： 1） At a frequency of 1 k Hz, αV of this device increases with the layer number of Metglas increased, and the maximum value of αV is about 4.25 times than the minimum; 2） At a frequency of 5 k Hz, the maximum value of αV is 458 mV /Oe, which derives from the ME device with three layers Metglas. This novel design provides an effective way to manufacture miniature and high sensitive ME devices, which makes it possible to apply ME device into integrated circuit（IC）.

大n值准相纯二维卤化物钙钛矿:从材料到器件的工具箱

Despite their excellent environmental stability,low defect density,and high carrier mobility,large-n quasi-two-dimensional halide perovskites(quasi-2DHPs)feature a limited application scope because of the formation of self-assembled multiple quantum wells(QWs)due to the similar thermal stabilities of large-n phases.However,large-n quasi-phase-pure 2DHPs(quasi-PP-2DHPs)can solve this problem perfectly.This review discusses the structures,formation mechanisms,and photoelectronic and physical properties of quasi-PP-2DHPs,summarises the corresponding single crystals,thin films,and heterojunction preparation methods,and presents the related advances.Moreover,we focus on applications of large-n quasi-PP-2DHPs in solar cells,photodetectors,lasers,light-emitting diodes,and field-effect transistors,discuss the challenges and prospects of these emerging photoelectronic materials,and review the potential technological developments in this area.

Polarization-directed nanophotonic routers based on twodimensional inorganic molecular crystals

Photonic and plasmonic hybrid nanostructures are the key solution for integratednanophotonic circuits with ultracompact size but relative low loss. However,the poor tunability and modulability of conventional waveguides makesthem cumbersome for optical multiplexing. Here we make use of twodimensionalmolecular crystal, α-Sb_(2)O_(3) as a dielectric waveguide via totalinternal reflection, which shows polarization-sensitive modulation of the propagatingbeams due to its large polarization mode dispersion. Both experimentsand simulations are performed to verify such concept. These Sb_(2)O_(3) nanoflakescan be coupled with plasmonic nanowires to form nanophotonic beam splittersand routers which can be easily modulated by changing the polarization of theincidence. It thus provides a robust, exploitable and tunable platform for onchipnanophotonics.

Tailoring component incorporation for homogenized perovskite solar cells

Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskite solar cells(PSCs)using the one-step spin-coating method.Here,we strategically employed sparingly soluble germanium iodide as a homogenized bulk in-situ reconstruction inducing material preferentially aggregated at the perovskite buried interface with gradient doping,markedly reducing deep-level traps and withstanding local lattice strain,while minimizing non-radiative recombination losses and enhancing the charge carrier lifetime over 9μs.Furthermore,this gradient doping assisted in modifying the band diagram at the buried interface into a desirable flattened alignment,substantially mitigating the energy loss of charge carriers within perovskite films and improving the carrier extraction equilibrium.As a result,the optimized device achieved a champion power conversion efficiency of 25.24% with a fill factor of up to 84.65%,and the unencapsulated device also demonstrated excellent light stability and humidity stability.This work provides a straightforward and reliable homogenization strategy of perovskite components for obtaining efficient and stable PSCs.

Breathing "Trap" Mechanism for C_(60) Nanocage

A new trap mechanism has been proposed to generate H@C 60 . Buckyball excited by shaped laser pulse could have large Raman-active vibration mode A g （1）, which enlarges and shrinks buckyball alternately, and raises and decreases the energy barrier repeatedly, forming a trap to capture the incoming H atom. In this trap mechanism, the A g （1） vibration mode is excited before the encapsulation process of H atom. Simulations of semiclassical electron-radiation-ion dynamics showed that the kinetic energy threshold for H atom in this mechanism was lowered from 17.51 eV to 10.51 eV, and successful encapsulation happened in the range from 10.51 eV to 15.55 eV.

Touchable cell biophysics property recognition platforms enable multifunctional blood smart health care

As a crucial biophysical property,red blood cell(RBC)deformability is pathologically altered in numerous disease states,and biochemical and structural changes occur over time in stored samples of otherwise normal RBCs.However,there is still a gap in applying it further to point-of-care blood devices due to the large external equipment(high-resolution microscope and microfluidic pump),associated operational difficulties,and professional analysis.Herein,we revolutionarily propose a smart optofluidic system to provide a differential diagnosis for blood testing via precise cell biophysics property recognition both mechanically and morphologically.Deformation of the RBC population is caused by pressing the hydrogel via an integrated mechanical transfer device.The biophysical properties of the cell population are obtained by the designed smartphone algorithm.Artificial intelligence-based modeling of cell biophysics properties related to blood diseases and quality was developed for online testing.We currently achieve 100%diagnostic accuracy for five typical clinical blood diseases(90 megaloblastic anemia,78 myelofibrosis,84 iron deficiency anemia,48 thrombotic thrombocytopenic purpura,and 48 thalassemias)via real-world prospective implementation;furthermore,personalized blood quality(for transfusion in cardiac surgery)monitoring is achieved with an accuracy of 96.9%.This work suggests a potential basis for next-generation blood smart health care devices.