Front and Back contact engineering for high-efficient and low-cost hydrothermal derived Sb_(2)(S, Se)_(3) solar cells by using FTO/SnO_(2) and carbon

Antimony chalcogenide Sb_(2)(S, Se)_(3) is attracting a lot of attention as photovoltaic absorber owing to its rewarding photoelectric properties, low toxicity, and earth abundance. However, its device efficiency is still limited by the absorber material quality and device interface recombination. In this work, a fluorinedoped tin oxide(FTO) substrate with ultra-thin SnO_(2) layer and a low-cost stabilized carbon paste are introduced as a front and back contact layer respectively in Sb_(2)(S, Se)_(3) based planar solar cells. Over 5.2% efficiency is demonstrated in the structure of FTO/SnO_(2)/Cd S/Sb_(2)(S, Se)_3/Carbon/Ag, where the Sb_(2)(S, Se)_(3) is prepared by hydrothermal technique. The complementary device physics characterizations reveal that the interfacial recombination between TCO and Cd S is significantly suppressed by the introduction of ultra-thin SnO_(2) layer, which is profited from the leakage protection and bandgap offset engineering by its high resistivity and suitable conduction band minimum. Meanwhile, the successful adoption of the lowcost stabilized carbon as a back contact here shows an enormous potential to replace the conventional organic hole transport materials and noble metal. We hope this work can provide positive guidance to optimize Sb_(2)(S, Se)_(3) based planar solar cells in the future.

Engineering upconverting core–shell nano-probe for spectral responsive fluid velocimetry

Particle velocimetry based on the temporal feature of upconversion luminescent nanocrystals is a newly-raising fluid velocimetry.Exploiting the availability to low flow rate fluid and exempting redundance external calibration(achieving once calibration for all)are highly expected and challenging.Herein,an engineered core–shell nano-probe,NaYF4:Yb/Ho/Ce@NaGdF4,was proposed,in which the Ce3+ions were utilized to manipulate the upconversion dynamic of Ho3+.Through optimization,a superior sensitive against low-speed flow is achieved,and the external calibrations before each operation can be avoided.Application demonstrations were conducted on a fluid circulation system with controllable flow rate.The fluid velocity was monitored successfully,no matter it is permanent,or cyclically variating(imitating the in vivo arterial blood).Moreover,this velocimetric route is competent in spatial scanning for handling the spatially inhomogeneous velocity field.Such sensing nanomaterial and fluid velocimetric method exhibit promising application potential in human blood velocimetry,industrial control,or environmental monitoring.

Plant-leaf-inspired MXene-silk composite for intelligent solar steam generation combined with mechanical actuation

Solar steam generators based on photothermal materials are important in producing fresh water.However,conventional solar steam generators are difficult to self-adapt to the complex external environment as organisms.Herein,inspired by the plant leaf,we propose a photothermal composite based on MXene and silk to add more functionality.On one hand,the composite achieves an evaporation rate of 1.51 kg·m^(−2)·h^(−1)and a conversion efficiency of 86.9%under a solar intensity of 1 kW·m^(−2),mimicking the water transpiration of plant leaf.On the other hand,the MXene-silk-based actuator shows a maximum bending curvature of 0.91 cm^(−1)under a solar intensity of 5 kW·m^(−2).Furthermore,an intelligent solar system is constructed utilizing the synergy of solar steam generator and actuator,which advances the research from the material level to the system level.Mimicking the behavior of plant leaf,the system can automatically open during the day to generate steam and fresh water.And at night or in bad weather,it will automatically close to prevent external pollution such as dust,achieving intelligent anti-fouling.This research will have good application prospects in less developed areas.Meanwhile,it also provides a certain reference value for exploring multi-functional photothermal devices in the future.

Compact ultrabroadband light-emitting diodes based on lanthanide-doped lead-free double perovskites

Impurity doping is an effective approach to tuning the optoelectronic performance of host materials by imparting extrinsic electronic channels.Herein,a family of lanthanide(Ln^(3+))ions was successfully incorporated into a Bi:Cs_(2)AgInCl_(6) lead-free double-perovskite(DP)semiconductor,expanding the spectral range from visible(Vis)to near-infrared(NIR)and improving the photoluminescence quantum yield(PLQY).After multidoping with Nd,Yb,Er and Tm,Bi/Ln:Cs_(2)AgInCl_(6) yielded an ultrabroadband continuous emission spectrum with a full width at half-maximum of~365 nm originating from intrinsic self-trapped exciton recombination and abundant 4f-4f transitions of the Ln^(3+)dopants.Steady-state and transient-state spectra were used to ascertain the energy transfer and emissive processes.To avoid adverse energy interactions between the various Ln^(3+)ions in a single DP host,a heterogeneous architecture was designed to spatially confine different Ln^(3+)dopants via a“DP-in-glass composite”(DiG)structure.This bottom-up strategy endowed the prepared Ln^(3+)-doped DIG with a high PLQY of 40%(nearly three times as high as that of the multidoped DP)and superior long-term stability.Finally,a compact Vis-NIR ultrabroadband(400~2000 nm)light source was easily fabricated by coupling the DiG with a commercial UV LED chip,and this light source has promising applications in nondestructive spectroscopic analyses and multifunctional lighting.

Self-supported hard carbon anode from fungus-treated basswood towards sodium-ion batteries

Hard carbon derived from biomass is regarded as a promising anode material for sodium-ion batteries(SIBs)because of its low operating potential,high capacity,resource availability,and low cost.However,scientific and technological challenges still exist to prepare hard carbon with a high initial Coulombic efficiency(ICE),an excellent rate capability,and good cycling stability.In this work,we report a self-supported hard carbon electrode from fungus-pretreated basswood with an improved graphitization degree and a low tortuosity.Compared with the hard carbon derived from basswood,the hard carbon electrode from fungus-pretreated basswood has an improved rate capability of 242.3 mAh·g^(−1)at 200 mA·g^(−1)and cycling stability with 93.9%of its capacity retention after 200 cycles at 40 mA·g^(−1),as well as the increased ICE from 84.3%to 88.2%.Additionally,ex-situ X-ray diffraction indicates that Na+adsorption caused the sloping capacity,whereas Na+intercalation between interlayer spacing corresponded to the low potential plateau capacity.This work provides a new perspective for the preparation of high-performance hard carbon and gains the in-depth understanding of Na storage mechanism.

Patterned phosphor-in-glass films with efficient thermal management for high-power laser projection displays

Recently,high-performance color converters excitable by blue laser diode(LD)have sprung up for projection displays.However,the thermal accumulation effect of the color converters is a non-negligible problem under high-power LD irradiation.Herein,we developed novel opto-functional composites(patterned CaAlSiN3:Eu^(2+)phosphor-in-glass film–Y_(3)Al_(5)O_(12):Ce^(3+)phosphor-in-glass film@Al_(2)O_(3)plate with aluminum"heat sink")via a thermal management methodology of combining"phosphor wheel"and"heat sink"for a lighting source of highpower laser projection displays.This new composite design makes it effective to transport generated thermal phonons away to reduce the thermal ionization process,and to yield stable and high-quality white light with brightness of 4510 lm@43 W,luminous efficacy of 105 lm/W,correlated color temperature of 3541 K,and color rendering index of 80.0.Furthermore,the phosphor-in-glass film-converted laser projection system was also successfully designed,showing a more vivid color effect compared to a traditional LED-based projector.This work emphasizes the importance of the thermal management upon high-power laser irradiation,and hopefully facilitates the development of a new LD-driven lighting source for high-power laser projection displays.

Photo-thermoelectric generator integrated in graphene-based actuator for self-powered sensing function

Smart actuators integrated with sensing functions are taking a significant role in constructing intelligent robots.However,the detection of sensing signals in most actuators requires external electrical power,lacking in the self-powered feature.Herein,we report a graphene-based light-driven actuator with self-powered sensing function,which is designed by integrating a photothermoelectric generator into the actuator intelligently.When one part of the actuator is irradiated by near-infrared light,it shows a deformation with bending curvature up to 1.5 cm^(−1),owing to the mismatch volume changes between two layers of the actuator.Meanwhile,the temperature difference across the actuator generates a voltage signal due to the photo-thermoelectric effect.The Seebeck coefficient is higher than 40μV/K.Furthermore,the self-powered voltage signal is consistent with the deformation trend,which can be used to characterize the deformation state of actuator without external electrical power.We further demonstrate a gripper and a bionic hand.Their deformations mimic the motions of human hand(or finger),even making complex gestures.Concurrently,they can output self-powered voltage signals for sensing.We hope this research will pave a new way for selfpowered devices,state-of-the-art intelligent robots,and other integrated multi-functional systems.