The emergence of cesium lead halide perovskite materials stable at air opened new prospects for the optoelectronic industry.In this work we present an approach to fabricating a flexible green perovskite light-emitting...The emergence of cesium lead halide perovskite materials stable at air opened new prospects for the optoelectronic industry.In this work we present an approach to fabricating a flexible green perovskite light-emitting electrochemical cell(PeLEC)with a CsPbBr_(3)perovskite active layer using a highly-ordered silicon nanowire(Si NW)array as a distributed electrode integrated within a thin polydimethylsiloxane film(PDMS).Numerical simulations reveal that Si NWs-based distributed electrode aids the improvement of carrier injection into the perovskite layer with an increased thickness and,therefore,the enhancement of light-emitting performance.The X-ray diffraction study shows that the perovskite layer synthesized on the PDMS membrane with Si NWs has a similar crystal structure to the ones synthesized on planar Si wafers.We perform a comparative analysis of the light-emitting devices’properties fabricated on rigid silicon substrates and flexible Si NW-based membranes released from substrates.Due to possible potential barriers in a flexible PeLEC between the bottom electrode(made of a network of single-walled carbon nanotube film)and Si NWs,the electroluminescence performance and Ⅰ-V properties of flexible devices deteriorated compared to rigid devices.The developed PeLECs pave the way for further development of inorganic flexible uniformly light-emitting devices with improved properties.展开更多
Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allo...Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.展开更多
Metal halide perovskite solar cells have attracted considerable attention because of their high-power conversion efficiency and costeffective solution-processable fabrication;however,they exhibit poor structural stabi...Metal halide perovskite solar cells have attracted considerable attention because of their high-power conversion efficiency and costeffective solution-processable fabrication;however,they exhibit poor structural stability.Two-dimensional(2D)Ruddlesden-Popper(RP)perovskites could address the aforementioned issue and present excellent stability because of their hydrophobic organic spacer cations.However,the crystallographic orientation of 2D crystals should be perpendicular to the bottom substrates for charges to transport fast and be collected in solar cells.Moreover,controlling the crystallographic orientation of the 2D RP perovskites prepared by the solution process is difficult.Herein,we reviewed the progress of recent research regarding 2D RP perovskite films with the focus on the crystallographic orientation mechanism and orientation controlling methods.Furthermore,the current issues and prospects of 2D RP perovskites in the photovoltaic field were discussed to elucidate their development and application in the future.展开更多
TiC based cermets were produced with FeCr, as a binder, by conventional P/M （powder metallurgy） to near 〉97% of the theoretical density. Sintering temperature significantly affects the mechanical properties of the ...TiC based cermets were produced with FeCr, as a binder, by conventional P/M （powder metallurgy） to near 〉97% of the theoretical density. Sintering temperature significantly affects the mechanical properties of the composite. The sintering temperature of 〉1360℃ caused severe chemical reaction between TiC particles and the binder phase. In the TiC-FeCr cermets, the mechanical properties did not vary linearly with the carbide content. Optimum mechanical properties were found in the composite containing 57wt% TiC reinforcement, when sintered at 1360℃ for 1 h. Use of carbon as an additive enhanced the mechanical properties of the composites. Cermets containing carbon as an additive with 49wt% TiC exhibited attractive mechanical properties. The microstructure of the developed composite contained less or no debonding, representing good wettabifity of the binder with TiC particles. Homogeneous distribution of the TiC particles ensured the presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite. Preliminary experiments for evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.展开更多
Metal halide perovskite light-emitting diodes(PeLEDs)show great potential in ultra-high-definition displays,due to their narrowband emission,wide color gamut(~140%),and cost-effective solution processability[1].Thanks...Metal halide perovskite light-emitting diodes(PeLEDs)show great potential in ultra-high-definition displays,due to their narrowband emission,wide color gamut(~140%),and cost-effective solution processability[1].Thanks to scientists'tremendous efforts,the external quantum efficiencies(EQEs)for the state-of-the-art PeLEDs emitting near-infrared and green light have reached 21.6%[2]and 23.4%[3],respectively.However,blue PeLEDs,as one of the essential technologies for perovskite-based high-resolution monitors and white light-ing,are still inferior to their red and green counterparts.展开更多
Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierar...Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.展开更多
To date, the instability of organometal halide perovskite solar cells（PSCs） has become the focus issue that limits the development and long-term application of PSCs. Both the ultraviolet（UV） rays in sunlight and m...To date, the instability of organometal halide perovskite solar cells（PSCs） has become the focus issue that limits the development and long-term application of PSCs. Both the ultraviolet（UV） rays in sunlight and moisture in air can significantly accelerate the disintegration of the perovskite. Here, we introduced a Zn Se quantum dots layer as downshifting materials, which was spin-coated onto the backside of PSCs.This layer converted the UV rays into visible light to prevent the destruction of PSCs as well as increase the light harvesting of the perovskite layer. Under the UV irradiation in the moisture ambient（40%）, the destruction speed of the unencapsulated perovskite films were also delayed evidently. In addition, the power conversion efficiency（PCE） of the PSCs was increased from 16.6% to 17.3% due to the increase of the visible light absorbance of the perovskite.展开更多
BiFeO_(3)(BFO)has received considerable attention as a lead-free ferroelectric film due to its large theoretical remnant polariza-tion.However,BFO suffers from a large leakage current,resulting in poor ferroelectric p...BiFeO_(3)(BFO)has received considerable attention as a lead-free ferroelectric film due to its large theoretical remnant polariza-tion.However,BFO suffers from a large leakage current,resulting in poor ferroelectric properties.Herein,the sol-gel method was used to deposit a series of BFO-based thin films on fluorine-doped tin oxide substrates,and the effects of the substitution of the elements Co,Cu,Mn(B-site)and Sm,Eu,La(A-site)on the crystal structure,ferroelectricity,and leakage current of the BFO-based thin films were invest-igated.Results confirmed that lattice distortion by X-ray diffraction can be attributed to the substitution of individual elements in the BFO-based films.Sm and Eu substitutions contribute to the lattice distortion in a pseudo-cubic structure,while La is biased toward pseudo-tet-ragonal.Piezoelectric force microscopy confirmed that reversible switching of ferroelectric domains by nearly 180°can be realized through the prepared films.The ferroelectric hysteresis loops showed that the order for the polarization contribution is as follows:Cu>Co>Mn(B-site),Sm>La>Eu(A-site).The current density voltage curves indicated that the order for leakage contribution is as follows:Mn<Cu<Co(B-site),La<Eu<Sm(A-site).Scanning electron microscopy showed that the introduction of Cu elements facilitates the formation of dense grains,and the grain size distribution statistics proved that La element promotes the reduction of grain size,leading to the increase of grain boundaries and the reduction of leakage.Finally,a Bi_(0.985)Sm_(0.045)La_(0.03)Fe_(0.96)Co_(0.02)Cu_(0.02)O_(3)(SmLa-CoCu)thin film with a qualitative leap in the remnant polarization from 25.5(Bi_(0.985)Sm_(0.075)FeO_(3))to 98.8µC/cm^(2)(SmLa-CoCu)was prepared through the syner-gistic action of Sm,La,Co,and Cu elements.The leakage current is also drastically reduced from 160 to 8.4 mA/cm^(2)at a field strength of 150 kV/cm.Thus,based on the increasing entropy strategy of chemical engineering,this study focuses on enhancing ferroelectricity and decreasing leakage current,providing a promising path for the advancement of ferroelectric devices.展开更多
Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of p...Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of pure HfO_(2)limits its application potential in advanced ferroelectric devices.Here,an ultrahigh remanent polarization is successfully achieved in the Ce-doped HfO_(2)films through a chemical negative strain due to the biaxial strain engineering strategy.The Ce-doped HfO_(2)films with regulated ions concentrations are fabricated on crystallographic-oriented substrates,and the effects of substrate-induced strain on the film growth were systematically investigated.Notably,the Ce-doped HfO_(2)films grown on(011)oriented substrates exhibit an excellent remanent polarization(2P_(t)=102.1µC/cm^(2),representing the highest value reported for HfO_(2)-based ferroelectrics,along with the outstanding fatigue resistance(<10%degradation after 107 switching cycles).This work provides a novel strategy for developing high-performance HfO_(2)-based ferroelectric materials through strain engineering,laying a critical foundation for their applications in non-volatile memory technologies.展开更多
Copper selenide （CurSe） has great potential as counter electrode for quantum dots sensitized solar cell （QDSSC） due to its excellent electrocatalytic activity and lower charge transfer resistance. A novel ion exch...Copper selenide （CurSe） has great potential as counter electrode for quantum dots sensitized solar cell （QDSSC） due to its excellent electrocatalytic activity and lower charge transfer resistance. A novel ion exchange method has been utilized to fabricate Cu3Se2 nanosheets array counter electrode. CdS layer was first deposited by sputtering and used as a template to grow compact and uni- form Cu3Se2 film in a typical chemical bath. The morphology and thickness of the Cu3Se2 nanosheets were controlled by the deposition time. The final products （2h-Cu3Se2） showed significantly improved electrochemical catalytic activity and carrier transport property, leading to a much increased power conversion efficiency （4.01%） when compared with the CuS counter electrode CdS/CdSe QDSSC （3.21%）.展开更多
The power conversion efficiency(PCE)of organic-inorganic hybrid metal halide perovskite solar cells(PSCs)has rocketed from around 3%to more than 25%in a decade,showing a miracle in the development history of photovolt...The power conversion efficiency(PCE)of organic-inorganic hybrid metal halide perovskite solar cells(PSCs)has rocketed from around 3%to more than 25%in a decade,showing a miracle in the development history of photovoltaics^([1]).However,the hybrid perovskites still suffer from the issue of thermodynamic instability due to the volatile organic cations in perovskites.All-inorganic metal halide perovskites.展开更多
Among all the excitonic solar cells(ESCs)including dyesensitized solar cells(DSSCs),quantum solar cells(QDSCs),perovskites solar cells(PSCs),and organic photovoltaics(OPVs),PSCs attracted enormous research attention i...Among all the excitonic solar cells(ESCs)including dyesensitized solar cells(DSSCs),quantum solar cells(QDSCs),perovskites solar cells(PSCs),and organic photovoltaics(OPVs),PSCs attracted enormous research attention in the past 7 years and attained the highest power conversion efficiency(PCE)of over 20%with the biggest progress,from 3.8%to over 22.1%in 7 years.However,one can easily realize the fact that such a rapid progress achieved in PSCs was made possible is largely based on the fundamental knowledge,experimental skills,and characterization facilities obtained and accumulated through the multi-decade long endeavor in the study of other excitonic solar cells.Even though PSCs have attractedmuch research human resource and funding,the study on other excitonic solar cells has never stopped,and such persistent展开更多
The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultr...The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultrafast optical memories,sensors and actuators with strain engineering.The mechanism of screening of the depolarization field by photoinduced carriers is generally accepted for UPS in ferroelectrics,while the thermal component of the strain is usually diluted as the offset and has not been systematically confronted,leading to unnecessary confusion.Herein,both the positive and negative thermal expansion effects in composite ferroelectric epitaxial films are investigated by use of high-repetition-rate ultrafast X-ray diffraction,along with the piezoelectric and photovoltaic effects.The coupling of the positive/negative thermal effects and the piezoelectric/photovoltaic effects in ultrafast strain is evidenced and can be regulated.The opposite lattice responses due to different thermal effects of the samples with different axial ratios are observed.The maximum UPS is up to 0.24%,comparable to that of conventional ferroelectric.The interaction between the thermal and ferroelectric effects in the induced strain could promote the diversified applications with the coupling of light,heat and electricity.展开更多
Quantum dot light-emitting diodes(QLEDs)have attracted considerable attention in displays owing to their high color purity,wide gamut,narrow emission band,and solution-processed characteristics.However,a major problem...Quantum dot light-emitting diodes(QLEDs)have attracted considerable attention in displays owing to their high color purity,wide gamut,narrow emission band,and solution-processed characteristics.However,a major problem of the unbalanced carrier(electrons and holes)injection in QLEDs deteriorates their performance.Here,we balanced the charge injection in QLEDs by optimizing the carrier transport layers.Different organic hole transport layers(HTLs)with a suitable thickness were employed to match the electron transport layer(ETL)of ZnO.Mg^(2+) was doped into the ZnO(MZO)ETL to decrease the electron mobility and match the hole mobility of the HTL.Consequently,the QLEDs exhibited an excellent external quantum efficiency(EQE)of 21.10%at a luminance of 4661 cd m^(-2).In the luminance range of 100–30,000 cd m^(-2),EQE roll-off was considerably low,and more than 80%of the initial EQE value could be maintained,indicating less Auger recombination because of the balanced carrier injection.This work reveals that compared with energy level matching,the charge transfer capability of the transport layers is more instrumental in the charge balance regulation of QLED devices.展开更多
Solution-processed cadmium-based quantum dots(QDs)light-emitting diodes(QLEDs)have shown promising for high-definition display panels due to their high colour purity and low-cost fabrication,but the toxicity still is ...Solution-processed cadmium-based quantum dots(QDs)light-emitting diodes(QLEDs)have shown promising for high-definition display panels due to their high colour purity and low-cost fabrication,but the toxicity still is a big threat.InP is considered as the most promising cadmium-free material to achieve high performance QLEDs,however,the performance of the InP-based QLEDs is far behind of the cadmium-based counterparts.Here,we report high efficiency InP-based QLEDs with more than 20%of external quantum efficiency(EQE)by suppressing hole injection loss.This suppression is achieved by doping a strong Lewis acid into a Lewis base poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)to form a Lewis acid-base adduct hole-transport layer(HTL),which improves the hole mobility of the HTL,reduces the hole transfer barrier between HTL and QDs layer to increase hole transport capability.This eventually leads to a more balanced carrier-injection through accelerating hole-injection to match well with the rate of electron-injection,thus suppressing the hole injection loss in the QLED.The InP-based QLED shows EQE of 20.4%,current efficiency of 25.3 cd·A^(−1),turn-on voltage of 2.0 V,luminance of 24,000 cd·m^(−2).This strategy would be a constructive approach to reduce hole loss for p-n junction optoelectronics.展开更多
Search and development of clean sustainable energy or renewable energy become an imperative demand beyond the concerns of limited resource and cost of fossil fuels that our modern life is so much dependent on.Among al...Search and development of clean sustainable energy or renewable energy become an imperative demand beyond the concerns of limited resource and cost of fossil fuels that our modern life is so much dependent on.Among all the renewable energy,solar energy is the most abundant and likely to make the most significant contribution to the clean energy efforts.Although the usage of solar energy has展开更多
基金the Russian Science Foundation Project No.22-79-10286,https://rscf.ru/project/22-7910286/(synthesis of perovskites, PeLEC fabrication)the Russian Science Foundation Project No.23-79-01151 for NW/PDMS membrane fabrication and PeLEC characterization+1 种基金the Ministry of Science and Higher Education of the Russian Federation (Project. FZSR-2020-0007 within the framework of state task no. 075-03-2020-097/1) for the support of SWCNT synthesisthe Ministry of Science and Higher Education of the Russian Federation (Project FSRM-2022-0007) for NW fabrication
文摘The emergence of cesium lead halide perovskite materials stable at air opened new prospects for the optoelectronic industry.In this work we present an approach to fabricating a flexible green perovskite light-emitting electrochemical cell(PeLEC)with a CsPbBr_(3)perovskite active layer using a highly-ordered silicon nanowire(Si NW)array as a distributed electrode integrated within a thin polydimethylsiloxane film(PDMS).Numerical simulations reveal that Si NWs-based distributed electrode aids the improvement of carrier injection into the perovskite layer with an increased thickness and,therefore,the enhancement of light-emitting performance.The X-ray diffraction study shows that the perovskite layer synthesized on the PDMS membrane with Si NWs has a similar crystal structure to the ones synthesized on planar Si wafers.We perform a comparative analysis of the light-emitting devices’properties fabricated on rigid silicon substrates and flexible Si NW-based membranes released from substrates.Due to possible potential barriers in a flexible PeLEC between the bottom electrode(made of a network of single-walled carbon nanotube film)and Si NWs,the electroluminescence performance and Ⅰ-V properties of flexible devices deteriorated compared to rigid devices.The developed PeLECs pave the way for further development of inorganic flexible uniformly light-emitting devices with improved properties.
基金the National Key Research and Development Program of China (2022YFB3803300)the open research fund of Songshan Lake Materials Laboratory (2021SLABFK02)the National Natural Science Foundation of China (21961160720)。
文摘Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.
基金This work was financially supported by the National Key Research and Development Program of China(No.2017YFE0119700)the National Natural Science Found-ation of China(Nos.51961135107,51774034,and 51772026).
文摘Metal halide perovskite solar cells have attracted considerable attention because of their high-power conversion efficiency and costeffective solution-processable fabrication;however,they exhibit poor structural stability.Two-dimensional(2D)Ruddlesden-Popper(RP)perovskites could address the aforementioned issue and present excellent stability because of their hydrophobic organic spacer cations.However,the crystallographic orientation of 2D crystals should be perpendicular to the bottom substrates for charges to transport fast and be collected in solar cells.Moreover,controlling the crystallographic orientation of the 2D RP perovskites prepared by the solution process is difficult.Herein,we reviewed the progress of recent research regarding 2D RP perovskite films with the focus on the crystallographic orientation mechanism and orientation controlling methods.Furthermore,the current issues and prospects of 2D RP perovskites in the photovoltaic field were discussed to elucidate their development and application in the future.
文摘TiC based cermets were produced with FeCr, as a binder, by conventional P/M （powder metallurgy） to near 〉97% of the theoretical density. Sintering temperature significantly affects the mechanical properties of the composite. The sintering temperature of 〉1360℃ caused severe chemical reaction between TiC particles and the binder phase. In the TiC-FeCr cermets, the mechanical properties did not vary linearly with the carbide content. Optimum mechanical properties were found in the composite containing 57wt% TiC reinforcement, when sintered at 1360℃ for 1 h. Use of carbon as an additive enhanced the mechanical properties of the composites. Cermets containing carbon as an additive with 49wt% TiC exhibited attractive mechanical properties. The microstructure of the developed composite contained less or no debonding, representing good wettabifity of the binder with TiC particles. Homogeneous distribution of the TiC particles ensured the presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite. Preliminary experiments for evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.
基金J.Tian thanks the National Key Research and Development Program of China(2017YFE0119700)National Natural Science Foundation of China(51961135107,51774034,51772026)+2 种基金Beijing Natural Science Foundation(2182039)L.Ding thanks the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032 and 21961160720)for financial support.
文摘Metal halide perovskite light-emitting diodes(PeLEDs)show great potential in ultra-high-definition displays,due to their narrowband emission,wide color gamut(~140%),and cost-effective solution processability[1].Thanks to scientists'tremendous efforts,the external quantum efficiencies(EQEs)for the state-of-the-art PeLEDs emitting near-infrared and green light have reached 21.6%[2]and 23.4%[3],respectively.However,blue PeLEDs,as one of the essential technologies for perovskite-based high-resolution monitors and white light-ing,are still inferior to their red and green counterparts.
基金support of the National Natural Science Foundation of China(21901246,22105203 and 22175174)the Natural Science Foundation of Fujian Province(2020J01116 and 2021J06033)the China Postdoctoral Science Foundation(2021TQ0332 and 2021M703215).
文摘Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.
基金supported by the National Science Foundation of China (51774034, 51772026, 51611130063)the Fundamental Research Funds for the Central Universities (FRF-BD-16-012A)111 Project (No. B17003)
文摘To date, the instability of organometal halide perovskite solar cells（PSCs） has become the focus issue that limits the development and long-term application of PSCs. Both the ultraviolet（UV） rays in sunlight and moisture in air can significantly accelerate the disintegration of the perovskite. Here, we introduced a Zn Se quantum dots layer as downshifting materials, which was spin-coated onto the backside of PSCs.This layer converted the UV rays into visible light to prevent the destruction of PSCs as well as increase the light harvesting of the perovskite layer. Under the UV irradiation in the moisture ambient（40%）, the destruction speed of the unencapsulated perovskite films were also delayed evidently. In addition, the power conversion efficiency（PCE） of the PSCs was increased from 16.6% to 17.3% due to the increase of the visible light absorbance of the perovskite.
基金supported by the National Natural Science Foundation of China(No.22371013)the National Key Research and Development Program of China(No.2018YFA0703700)+3 种基金the Fundamental Research Funds for the Central Universities,China(Nos.FRF-IDRY-19-007 and FRF-TP-19-055A2Z)the National Program for Support of Top-notch Young Professionals,Chinathe Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(CAST),China(No.2019-2021 QNRC)the“Xiaomi Young Scholar”Funding Project,China.
文摘BiFeO_(3)(BFO)has received considerable attention as a lead-free ferroelectric film due to its large theoretical remnant polariza-tion.However,BFO suffers from a large leakage current,resulting in poor ferroelectric properties.Herein,the sol-gel method was used to deposit a series of BFO-based thin films on fluorine-doped tin oxide substrates,and the effects of the substitution of the elements Co,Cu,Mn(B-site)and Sm,Eu,La(A-site)on the crystal structure,ferroelectricity,and leakage current of the BFO-based thin films were invest-igated.Results confirmed that lattice distortion by X-ray diffraction can be attributed to the substitution of individual elements in the BFO-based films.Sm and Eu substitutions contribute to the lattice distortion in a pseudo-cubic structure,while La is biased toward pseudo-tet-ragonal.Piezoelectric force microscopy confirmed that reversible switching of ferroelectric domains by nearly 180°can be realized through the prepared films.The ferroelectric hysteresis loops showed that the order for the polarization contribution is as follows:Cu>Co>Mn(B-site),Sm>La>Eu(A-site).The current density voltage curves indicated that the order for leakage contribution is as follows:Mn<Cu<Co(B-site),La<Eu<Sm(A-site).Scanning electron microscopy showed that the introduction of Cu elements facilitates the formation of dense grains,and the grain size distribution statistics proved that La element promotes the reduction of grain size,leading to the increase of grain boundaries and the reduction of leakage.Finally,a Bi_(0.985)Sm_(0.045)La_(0.03)Fe_(0.96)Co_(0.02)Cu_(0.02)O_(3)(SmLa-CoCu)thin film with a qualitative leap in the remnant polarization from 25.5(Bi_(0.985)Sm_(0.075)FeO_(3))to 98.8µC/cm^(2)(SmLa-CoCu)was prepared through the syner-gistic action of Sm,La,Co,and Cu elements.The leakage current is also drastically reduced from 160 to 8.4 mA/cm^(2)at a field strength of 150 kV/cm.Thus,based on the increasing entropy strategy of chemical engineering,this study focuses on enhancing ferroelectricity and decreasing leakage current,providing a promising path for the advancement of ferroelectric devices.
基金the National Natural Science Foundation of China(22371013,92263205)the National Key Research and Development Program of China(2018YFA0703700)+3 种基金the Fundamental Research Funds for the Central Universities(FRF-IDRY-19-007 and FRF-TP-19-055A2Z)the National Program for Support of Top-notch Young Professionalsthe Young Elite Scientists Sponsorship Program by CAST(2019-2021QNRC)the"Xiaomi Young Scholar"Funding Project。
文摘Hafnium oxide(HfO_(2))-based ferroelectric materials have been widely applied in logic and memory devices due to their favorable ferroelectric and dielectric properties.However,the weak ferroelectric polarization of pure HfO_(2)limits its application potential in advanced ferroelectric devices.Here,an ultrahigh remanent polarization is successfully achieved in the Ce-doped HfO_(2)films through a chemical negative strain due to the biaxial strain engineering strategy.The Ce-doped HfO_(2)films with regulated ions concentrations are fabricated on crystallographic-oriented substrates,and the effects of substrate-induced strain on the film growth were systematically investigated.Notably,the Ce-doped HfO_(2)films grown on(011)oriented substrates exhibit an excellent remanent polarization(2P_(t)=102.1µC/cm^(2),representing the highest value reported for HfO_(2)-based ferroelectrics,along with the outstanding fatigue resistance(<10%degradation after 107 switching cycles).This work provides a novel strategy for developing high-performance HfO_(2)-based ferroelectric materials through strain engineering,laying a critical foundation for their applications in non-volatile memory technologies.
基金supported by the National Natural Science Foundation of China (51374029 and 51611130063)Fundamental Research Funds for the Central Universities (FRF-BD-16-012A)111 Project (B17003)
文摘Copper selenide （CurSe） has great potential as counter electrode for quantum dots sensitized solar cell （QDSSC） due to its excellent electrocatalytic activity and lower charge transfer resistance. A novel ion exchange method has been utilized to fabricate Cu3Se2 nanosheets array counter electrode. CdS layer was first deposited by sputtering and used as a template to grow compact and uni- form Cu3Se2 film in a typical chemical bath. The morphology and thickness of the Cu3Se2 nanosheets were controlled by the deposition time. The final products （2h-Cu3Se2） showed significantly improved electrochemical catalytic activity and carrier transport property, leading to a much increased power conversion efficiency （4.01%） when compared with the CuS counter electrode CdS/CdSe QDSSC （3.21%）.
文摘The power conversion efficiency(PCE)of organic-inorganic hybrid metal halide perovskite solar cells(PSCs)has rocketed from around 3%to more than 25%in a decade,showing a miracle in the development history of photovoltaics^([1]).However,the hybrid perovskites still suffer from the issue of thermodynamic instability due to the volatile organic cations in perovskites.All-inorganic metal halide perovskites.
文摘Among all the excitonic solar cells(ESCs)including dyesensitized solar cells(DSSCs),quantum solar cells(QDSCs),perovskites solar cells(PSCs),and organic photovoltaics(OPVs),PSCs attracted enormous research attention in the past 7 years and attained the highest power conversion efficiency(PCE)of over 20%with the biggest progress,from 3.8%to over 22.1%in 7 years.However,one can easily realize the fact that such a rapid progress achieved in PSCs was made possible is largely based on the fundamental knowledge,experimental skills,and characterization facilities obtained and accumulated through the multi-decade long endeavor in the study of other excitonic solar cells.Even though PSCs have attractedmuch research human resource and funding,the study on other excitonic solar cells has never stopped,and such persistent
基金supported by the National Key Research and Development Program of China(2018YFA0703700 and 2017YFE0119700)the National Natural Science Foundation of China(21801013,1190524,51774034 and 51961135107)+2 种基金Beijing Natural Science Foundation(2182039)the Fundamental Research Funds for the Central Universities(FRF-IDRY-19-007 and FRF-TP-19-055A2Z)the Young Elite Scientists Sponsorship Program by CAST(20192021QNRC)。
文摘The ultrafast photoinduced strain(UPS)resulting from the coupling of piezoelectric and photovoltaic effects in ferroelectric has been focused in the last decade,endowing them with extensive applications including ultrafast optical memories,sensors and actuators with strain engineering.The mechanism of screening of the depolarization field by photoinduced carriers is generally accepted for UPS in ferroelectrics,while the thermal component of the strain is usually diluted as the offset and has not been systematically confronted,leading to unnecessary confusion.Herein,both the positive and negative thermal expansion effects in composite ferroelectric epitaxial films are investigated by use of high-repetition-rate ultrafast X-ray diffraction,along with the piezoelectric and photovoltaic effects.The coupling of the positive/negative thermal effects and the piezoelectric/photovoltaic effects in ultrafast strain is evidenced and can be regulated.The opposite lattice responses due to different thermal effects of the samples with different axial ratios are observed.The maximum UPS is up to 0.24%,comparable to that of conventional ferroelectric.The interaction between the thermal and ferroelectric effects in the induced strain could promote the diversified applications with the coupling of light,heat and electricity.
基金supported by the National Natural Science Foundation of China(51774034,51961135107 and 51772026)the National Key Research&Development Program of China(2017YFE0119700)。
文摘Quantum dot light-emitting diodes(QLEDs)have attracted considerable attention in displays owing to their high color purity,wide gamut,narrow emission band,and solution-processed characteristics.However,a major problem of the unbalanced carrier(electrons and holes)injection in QLEDs deteriorates their performance.Here,we balanced the charge injection in QLEDs by optimizing the carrier transport layers.Different organic hole transport layers(HTLs)with a suitable thickness were employed to match the electron transport layer(ETL)of ZnO.Mg^(2+) was doped into the ZnO(MZO)ETL to decrease the electron mobility and match the hole mobility of the HTL.Consequently,the QLEDs exhibited an excellent external quantum efficiency(EQE)of 21.10%at a luminance of 4661 cd m^(-2).In the luminance range of 100–30,000 cd m^(-2),EQE roll-off was considerably low,and more than 80%of the initial EQE value could be maintained,indicating less Auger recombination because of the balanced carrier injection.This work reveals that compared with energy level matching,the charge transfer capability of the transport layers is more instrumental in the charge balance regulation of QLED devices.
基金the Beijing Municipal Natural Science Foundation(No.2222061)the National Natural Science Foundation of China(Nos.51961135107 and 51774034)the National Key Research and Development Program of China(No.2017YFE0119700).
文摘Solution-processed cadmium-based quantum dots(QDs)light-emitting diodes(QLEDs)have shown promising for high-definition display panels due to their high colour purity and low-cost fabrication,but the toxicity still is a big threat.InP is considered as the most promising cadmium-free material to achieve high performance QLEDs,however,the performance of the InP-based QLEDs is far behind of the cadmium-based counterparts.Here,we report high efficiency InP-based QLEDs with more than 20%of external quantum efficiency(EQE)by suppressing hole injection loss.This suppression is achieved by doping a strong Lewis acid into a Lewis base poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)to form a Lewis acid-base adduct hole-transport layer(HTL),which improves the hole mobility of the HTL,reduces the hole transfer barrier between HTL and QDs layer to increase hole transport capability.This eventually leads to a more balanced carrier-injection through accelerating hole-injection to match well with the rate of electron-injection,thus suppressing the hole injection loss in the QLED.The InP-based QLED shows EQE of 20.4%,current efficiency of 25.3 cd·A^(−1),turn-on voltage of 2.0 V,luminance of 24,000 cd·m^(−2).This strategy would be a constructive approach to reduce hole loss for p-n junction optoelectronics.
文摘Search and development of clean sustainable energy or renewable energy become an imperative demand beyond the concerns of limited resource and cost of fossil fuels that our modern life is so much dependent on.Among all the renewable energy,solar energy is the most abundant and likely to make the most significant contribution to the clean energy efforts.Although the usage of solar energy has
