The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials develop...The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials development,so that a majority of the PSMAs have not fulfilled their potentials.Furthermore,most high-performance all-PSCs rely on the use of chloroform as the processing solvent.For instance,the recent highperformance PSMA,named PJ1-γ,with high LUMO,and HOMO levels,could only achieve a PCE of 16.1%with a high-energy-level donor(JD40)using chloroform.Herein,we present a methodology combining sequential processing(SqP)with the addition of 0.5%wt PC_(71)BM as a solid additive(SA)to achieve an impressive efficiency of 18.0%for all-PSCs processed from toluene,an aromatic hydrocarbon solvent.Compared to the conventional blend-casting(BC)method whose best efficiency(16.7%)could only be achieved using chloroform,the SqP method significantly boosted the device efficiency using toluene as the processing solvent.In addition,the donor we employ is the classic PM6 that has deeper energy levels than JD40,which provides low energy loss for the device.We compare the results with another PSMA(PYF-T-o)with the same method.Finally,an improved photostability of the SqP devices with the incorporation of SA is demonstrated.展开更多
Solar greenhouse with trapezoidal soil wall is widely used due to its good heat retaining property and cost efficiency.In this study, solar irradiance, heat flux and the temperature 0.05 and 0.3 m from the inner surfa...Solar greenhouse with trapezoidal soil wall is widely used due to its good heat retaining property and cost efficiency.In this study, solar irradiance, heat flux and the temperature 0.05 and 0.3 m from the inner surface of the wall at the upper,middle and lower measured positions were determined to study the thermal condition of the trapezoidal soil wall in solar greenhouse. The results showed: first, both the solar irradiance and the temperature increased from the upper to the lower measured position. Second, the heat absorption also increased from the upper to the lower measured position. In clear day, the heat absorption at the three measured positions accounted for 31.4%, 32.6% and 36.0% of the total amount of heat absorption of the whole wall. In cloudy day, the heat absorption at the three measured positions were 0.249, 0.370 and 0.440 MJ/m^2, which accounted for 23.5%, 35.0% and 41.4% of the total amount of heat absorption of the whole wall. When P<0.05, the heat fluxes were strikingly different between the upper and lower measured positions. But when P<0.01, the heat flux had no big difference among the three measured positions. Third, in clear day, the heat emission was the biggest at the middle measured position and smallest at the upper measured position. The heat emission at the three measured positions accounted for 27.5%, 36.7%and 35.8% of the total amount of heat emission of the whole wall. And the heat emission between the middle and lower measured position was not strikingly different. In cloudy day, the heat emission was the biggest at the lower measured position and smallest at the upper measured position. The average heat emission at the three measured positions accounted for 26.1%,36.4% and 37.4% of the total amount of heat emission of the whole wall. Fourthly, correlativity, the solar irradiance directly influenced the heat absorption and had close relation with heat emission. And heat emission again had close relation with the temperature in the greenhouse. Solar irradiance directly influences the thermal condition of a solar green house. It is hoped that this study can be referred to optimize trapezoidal structure and to improve the thermal conditions of the solar greenhouse.展开更多
Objective:To study the relationship between umbilical blood flow ultrasound characteristics of perioperative fetal intrauterine hypoxia and maternal as well as fetal oxidative stress injury.Methods: 108 puerperae givi...Objective:To study the relationship between umbilical blood flow ultrasound characteristics of perioperative fetal intrauterine hypoxia and maternal as well as fetal oxidative stress injury.Methods: 108 puerperae giving birth in our hospital between May 2014 and October 2016 were selected and divided into normal pregnancy group with neonatal Apgar score >7 points and intrauterine hypoxia group with neonatal Apgar score≤7 points, color Doppler diasonograph was used to determine umbilical blood flow ultrasound parameters, umbilical cord blood was collected to determine the levels of oxidative stress products, and the placenta was collected to determine the levels of oxidative stress products and related apoptosis molecules.Results: During 24–30 weeks, 31–36 weeks and 37–41 weeks of pregnancy, umbilical blood flow resistance index (RI), pulsatility index (PI) and diastolic velocity/systolic velocity (S/D) of intrauterine hypoxia group were significantly higher than those of normal pregnancy group (P<0.05);malondialdehyde (MDA), oxidized low-density lipoprotein (ox-LDL), 8-isoprostanes (8-iso), and heat shock protein 70 (HSP-70) levels in umbilical cord blood of intrauterine hypoxia group were significantly higher than those of normal pregnancy group (P<0.05), MDA, oxLDL, 8-ios, HSP-70, Fas, FasL and Bax levels in placenta tissue were significantly higher than those of normal pregnancy group (P<0.05), and Bcl-2 and XIAP levels were significantly lower than those of normal pregnancy group (P<0.05);RI, PI and S/D were positively correlated with MDA, oxLDL, 8-ios and HSP-70 levels in umbilical cord blood and placenta tissue, positively correlated with Fas, FasL and Bax levels in placenta tissue, and negatively correlated with Bcl-2 and XIAP levels in placental tissue.Conclusions:The increased umbilical blood flow resistance and decreased flow volume of fetal intrauterine hypoxia are closely related to maternal, fetal and placental oxidative stress injury.展开更多
Wind erosion is widely recognised as one of the causes of soil degradation,which is exacerbated by the effects of freezing and thawing,and poses a serious threat to the sustainability of agricultural production.The me...Wind erosion is widely recognised as one of the causes of soil degradation,which is exacerbated by the effects of freezing and thawing,and poses a serious threat to the sustainability of agricultural production.The mechanisms of freeze-thaw effects on wind erosion in the Mollisols region have been the subject of considerable investigation from the perspective of what the impact of freeze-thaw processes have on soil aggregates.In contrast,the role of the physical crust in the mechanism of freeze-thaw effects on wind erosion remains uncertain.In this study,for disentangling the changes in environmental conditions(freeze-thaw cycles(FTCs),initial soil moisture(M))on aggregate size distribution,mean weight diameter(MWD),crust formation and their properties,and the roles played by these changes in influ-encing the magnitude of wind erosion(W),a wind tunnel simulation experiment was used to measure the wind erosion rate of erodible soil aggregates with four diameter ranges(D).The relationship between the variations in the distribution of aggregate sizes and the properties of the crust,as well as the impact of freezing and thawing on the distribution of aggregate sizes,were examined.The findings indicated that both aggregates and crust were susceptible to damage during the freeze-thaw cycle.The MWD of the aggregates exhibited a notable alteration following the 1st freeze-thaw cycle(p<0.05).There exists a good exponential correlation between the strength of the crust and the number of freeze-thaw cycles(R^(2)>0.70).The crust strength demonstrated a decline significantly with an increase in the number of freeze-thaw cycles.The variation tendency of crust strength tended to be flat and towards a minimum crust strength of 4.27 kPa(D_(0.5-1)),2.87 kPa(D_(0.25-0.5)),and 2.82 kPa(D_(<0.25))beyond 6th freeze-thaw cycles.The initial moisture content had a significant impact on the variation in aggregate sizes,with higher moisture leading to greater fluctuations in the variation percentage of aggregates breaking or aggregating.The percentage of de-aggregation(disintegration of soil aggregates)varied from 12.68%to 20.64%,while the percentage of re-aggregation(recombination of soil aggregates)varied from 0.84%to 10.78%.When the moisture content of the soil was greater than or equal to 12%,a physical crust formed on the surface of the constructed soil samples,with an approximate thickness of 1 mm.When D≥0.25 mm,the freezing-thawing effect was the primary cause of aggregate breakage,resulting in a reduction in MWD.When D<0.25 mm,the primary phenomenon was aggregation,which resulted in an increase in MWD.When D<1 mm,the formation of a physical crust on the constructed soil sample surface was facilitated.De-aggregation of aggregates increased the wind erosion rate by an average of 12.31%(M_(4%)),12.21%(M_(8%)),37.15%(M_(12%))and 43.47%(M_(16%))respectively.Conversely,re-aggregation led to a reduction in wind erosion rate by an average of 20.60%(M_(4%)),24.22%(M_(8%)),44.21%(M_(12%))and 34.46%(M_(16%)),respectively.The process of de-aggregation makes the aggregate size smaller,leading to an increase in wind soil erosion losses at the same wind speed.Re-aggregation process showed the opposite tendency.The formation of a crust greatly enhanced the soil surface strength and significantly reduced the degree of wind erosion,which decreased by 0.96%(M_(4%)),14.98%(M_(8%)),79.15%(M_(12%))and 107.23%(M_(16%)),respectively,after crust formation.Although the constructed soil samples formed crusts under different initial soil moisture levels,all samples had naturally air-dried to approximately 4%prior to the wind erosion experimental study was conducted.Therefore,there was no significant change in threshold wind velocity due to different sample moisture levels.In conclusion,we constructed a path model based on the effects of environmental conditions on the wind erosion rate.The results indicated that the initial soil moisture and freeze-thaw effect exerted an indirect influence on wind erosion,by mediating their impact on aggregate variation,MWD,crust strength and crust thickness.The relationship between wind erosion rate and topsoil(2 cm)properties was significant.The initial moisture content and the freeze-thaw effect contributed 30.4%and 49.2%,respectively,to the rate of wind erosion.This study clarifies the role played by the crust and aggregation in the influence of wind erosion under freeze-thaw conditions in the Mollisols region,and provides a scientific theoretical basis for the mechanism of spring wind erosion in cold regions.展开更多
In organic solar cells(OSCs),typical methods for fabricating the ternary active layer are blend-casting(BC)or two-step sequential processing(SqP-2T),where all three or at least two components are blended together,whic...In organic solar cells(OSCs),typical methods for fabricating the ternary active layer are blend-casting(BC)or two-step sequential processing(SqP-2T),where all three or at least two components are blended together,which affect the crystallization/aggregation behavior of each other during solid-film formation.Herein,we introduce for the first time a novel three-step sequential processing method,termed SqP-3T,which utilizes hydrocarbon solvents to prepare high-quality ternary active layers.Compared to the SqP-2T and BC techniques,SqP-3T yields an active layer with a higher acceptor ratio on its upper surface and exhibits a longer crystal coherence length in the out-of-plane direction(21.42 A).These characteristics enhance charge transport and collection.Additionally,SqP-3T devices demonstrate nearly a twofold increase in the transient photovoltage decay constant(up to 2.82μs)that is related to carrier lifetime to a certain extent,leading to reduced recombination losses.Consequently,the SqP-3T device achieves a high fill factor(75.67%)and a high short-circuit current density(27.35 mA/cm^(2)),contributing to a power conversion efficiency of 19.2%.These results highlight the potential of SqP-3T or a multi-step sequential deposition process in the production of ternary or multicomponent OSCs,which could be adopted by more material systems in the future.展开更多
Brillouin optical time domain reflectometry(BOTDR)inherently involves a trade-off between sensing range and spatial resolution,particularly in long-distance applications.This paper presents an image-deconvoluted rando...Brillouin optical time domain reflectometry(BOTDR)inherently involves a trade-off between sensing range and spatial resolution,particularly in long-distance applications.This paper presents an image-deconvoluted random coding BOTDR approach to simultaneously enhance both sensing range and spatial resolution.In this method,a series of pulses modulated with random codes is employed to extend the sensing range,while the Richardson-Lucy image deconvolution algorithm is applied to refine spatial resolution.The decoding principle for random pulse detection BOTDR is systematically described,and the corresponding point spread function(PSF)is constructed.Numerical simulations are conducted to optimize coding parameters,achieving a simulated spatial resolution of 1 m over a 100 km sensing fiber.The proposed method is experimentally implemented and thoroughly evaluated.The experiment results demonstrate that,without any hardware modifications,the combination of 256-bit random coding with 1oo ns single-code width and image deconvolution extends the sensing range of BOTDR to 100.4 km with a root-mean-square error(RMSE)below 2 MHz,while achieving an actual spatial resolution of 2 m at the fiber end.These findings indicate that the proposed approach can significantly improve both the sensing range and spatial resolution in BOTDR sensing systems.展开更多
Organic light-emitting diodes(OLEDs),which have been recently utilized in some flat-panel display screens such as mobile phones and televisions,show many merits,including light weight,high flexibility,energy preservat...Organic light-emitting diodes(OLEDs),which have been recently utilized in some flat-panel display screens such as mobile phones and televisions,show many merits,including light weight,high flexibility,energy preservation,and so forth,and are considered the next-generation displays and solid-state lightings.Blue-emitting materials that can be applied in nondoped OLEDs with little efficiency roll-offs at high brightness are of great importance.Here,a highly efficient,blue-emitting material,9-phenyl10-(4-(pyren-1-yl)phenyl)-9H-pyreno[4,5-d]imidazole(PyPI-Py),is achieved using pyrene[4,5-d]imidazole and pyrene as the weak electron donor and electron acceptor,respectively.The nondoped blue OLED exhibits excellent performance with a maximum brightness of 75,687 cd m^(−2),a maximum current efficiency of 13.38 cd A−1,and a maximum external quantum efficiency(ηext)of 8.52%.Moreover,theηext is maintained at 8.35%and 8.05%at a brightness of 10,000 and 50,000 cd m^(−2),respectively,displaying extremely small efficiency roll-offs of 2.0%and 5.5%.The device characteristics are among the highest values for nondoped blue OLEDs and correspond to the best performance obtained for nondoped pyrene-based blue OLEDs.The superior performance is attributed to the proper donor–acceptor design strategy which results in a quasi-equivalent hybrid local and charge-transfer excited state with the maximum generation of an 82%fraction of singlet excitons.展开更多
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2022A1515010875)Guangdong Basic and Applied Basic Research Foundation(2021A1515110017)+10 种基金Natural Science Foundation of Top Talent of SZTU(grant no.20200205)Project of Education Commission of Guangdong Province of China(2021KQNCX080)Research on the electrochemical reaction mechanism of the anode of mediumlow temperature direct ammonia SOFCs(20231063020006)the project of al solid-state high energy density energy storage system(20221063010031)the project of Shenzhen Overseas Talent upon Industrialization of 1kw stack for direct ammonia SOFCs(20221061010002)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515011673)Education Department of Guangdong Province(No.2021KCXTD045)National Natural Science Foundation of China(No.12274303)the support from the Fundamental Research Funds for the Central Universities(2232023A-01)NSFC No.52103202beamline BL16B1 at Shanghai Synchrotron Radiation Facility(SSRF)for the synchrotron experiment
文摘The emergence of polymerized small molecule acceptors(PSMAs)has significantly improved the performance of all-polymer solar cells(all-PSCs).However,the pace of device engineering lacks behind that of materials development,so that a majority of the PSMAs have not fulfilled their potentials.Furthermore,most high-performance all-PSCs rely on the use of chloroform as the processing solvent.For instance,the recent highperformance PSMA,named PJ1-γ,with high LUMO,and HOMO levels,could only achieve a PCE of 16.1%with a high-energy-level donor(JD40)using chloroform.Herein,we present a methodology combining sequential processing(SqP)with the addition of 0.5%wt PC_(71)BM as a solid additive(SA)to achieve an impressive efficiency of 18.0%for all-PSCs processed from toluene,an aromatic hydrocarbon solvent.Compared to the conventional blend-casting(BC)method whose best efficiency(16.7%)could only be achieved using chloroform,the SqP method significantly boosted the device efficiency using toluene as the processing solvent.In addition,the donor we employ is the classic PM6 that has deeper energy levels than JD40,which provides low energy loss for the device.We compare the results with another PSMA(PYF-T-o)with the same method.Finally,an improved photostability of the SqP devices with the incorporation of SA is demonstrated.
基金Supported by Ningxia Science and Technology Planning Program
文摘Solar greenhouse with trapezoidal soil wall is widely used due to its good heat retaining property and cost efficiency.In this study, solar irradiance, heat flux and the temperature 0.05 and 0.3 m from the inner surface of the wall at the upper,middle and lower measured positions were determined to study the thermal condition of the trapezoidal soil wall in solar greenhouse. The results showed: first, both the solar irradiance and the temperature increased from the upper to the lower measured position. Second, the heat absorption also increased from the upper to the lower measured position. In clear day, the heat absorption at the three measured positions accounted for 31.4%, 32.6% and 36.0% of the total amount of heat absorption of the whole wall. In cloudy day, the heat absorption at the three measured positions were 0.249, 0.370 and 0.440 MJ/m^2, which accounted for 23.5%, 35.0% and 41.4% of the total amount of heat absorption of the whole wall. When P<0.05, the heat fluxes were strikingly different between the upper and lower measured positions. But when P<0.01, the heat flux had no big difference among the three measured positions. Third, in clear day, the heat emission was the biggest at the middle measured position and smallest at the upper measured position. The heat emission at the three measured positions accounted for 27.5%, 36.7%and 35.8% of the total amount of heat emission of the whole wall. And the heat emission between the middle and lower measured position was not strikingly different. In cloudy day, the heat emission was the biggest at the lower measured position and smallest at the upper measured position. The average heat emission at the three measured positions accounted for 26.1%,36.4% and 37.4% of the total amount of heat emission of the whole wall. Fourthly, correlativity, the solar irradiance directly influenced the heat absorption and had close relation with heat emission. And heat emission again had close relation with the temperature in the greenhouse. Solar irradiance directly influences the thermal condition of a solar green house. It is hoped that this study can be referred to optimize trapezoidal structure and to improve the thermal conditions of the solar greenhouse.
文摘Objective:To study the relationship between umbilical blood flow ultrasound characteristics of perioperative fetal intrauterine hypoxia and maternal as well as fetal oxidative stress injury.Methods: 108 puerperae giving birth in our hospital between May 2014 and October 2016 were selected and divided into normal pregnancy group with neonatal Apgar score >7 points and intrauterine hypoxia group with neonatal Apgar score≤7 points, color Doppler diasonograph was used to determine umbilical blood flow ultrasound parameters, umbilical cord blood was collected to determine the levels of oxidative stress products, and the placenta was collected to determine the levels of oxidative stress products and related apoptosis molecules.Results: During 24–30 weeks, 31–36 weeks and 37–41 weeks of pregnancy, umbilical blood flow resistance index (RI), pulsatility index (PI) and diastolic velocity/systolic velocity (S/D) of intrauterine hypoxia group were significantly higher than those of normal pregnancy group (P<0.05);malondialdehyde (MDA), oxidized low-density lipoprotein (ox-LDL), 8-isoprostanes (8-iso), and heat shock protein 70 (HSP-70) levels in umbilical cord blood of intrauterine hypoxia group were significantly higher than those of normal pregnancy group (P<0.05), MDA, oxLDL, 8-ios, HSP-70, Fas, FasL and Bax levels in placenta tissue were significantly higher than those of normal pregnancy group (P<0.05), and Bcl-2 and XIAP levels were significantly lower than those of normal pregnancy group (P<0.05);RI, PI and S/D were positively correlated with MDA, oxLDL, 8-ios and HSP-70 levels in umbilical cord blood and placenta tissue, positively correlated with Fas, FasL and Bax levels in placenta tissue, and negatively correlated with Bcl-2 and XIAP levels in placental tissue.Conclusions:The increased umbilical blood flow resistance and decreased flow volume of fetal intrauterine hypoxia are closely related to maternal, fetal and placental oxidative stress injury.
文摘Wind erosion is widely recognised as one of the causes of soil degradation,which is exacerbated by the effects of freezing and thawing,and poses a serious threat to the sustainability of agricultural production.The mechanisms of freeze-thaw effects on wind erosion in the Mollisols region have been the subject of considerable investigation from the perspective of what the impact of freeze-thaw processes have on soil aggregates.In contrast,the role of the physical crust in the mechanism of freeze-thaw effects on wind erosion remains uncertain.In this study,for disentangling the changes in environmental conditions(freeze-thaw cycles(FTCs),initial soil moisture(M))on aggregate size distribution,mean weight diameter(MWD),crust formation and their properties,and the roles played by these changes in influ-encing the magnitude of wind erosion(W),a wind tunnel simulation experiment was used to measure the wind erosion rate of erodible soil aggregates with four diameter ranges(D).The relationship between the variations in the distribution of aggregate sizes and the properties of the crust,as well as the impact of freezing and thawing on the distribution of aggregate sizes,were examined.The findings indicated that both aggregates and crust were susceptible to damage during the freeze-thaw cycle.The MWD of the aggregates exhibited a notable alteration following the 1st freeze-thaw cycle(p<0.05).There exists a good exponential correlation between the strength of the crust and the number of freeze-thaw cycles(R^(2)>0.70).The crust strength demonstrated a decline significantly with an increase in the number of freeze-thaw cycles.The variation tendency of crust strength tended to be flat and towards a minimum crust strength of 4.27 kPa(D_(0.5-1)),2.87 kPa(D_(0.25-0.5)),and 2.82 kPa(D_(<0.25))beyond 6th freeze-thaw cycles.The initial moisture content had a significant impact on the variation in aggregate sizes,with higher moisture leading to greater fluctuations in the variation percentage of aggregates breaking or aggregating.The percentage of de-aggregation(disintegration of soil aggregates)varied from 12.68%to 20.64%,while the percentage of re-aggregation(recombination of soil aggregates)varied from 0.84%to 10.78%.When the moisture content of the soil was greater than or equal to 12%,a physical crust formed on the surface of the constructed soil samples,with an approximate thickness of 1 mm.When D≥0.25 mm,the freezing-thawing effect was the primary cause of aggregate breakage,resulting in a reduction in MWD.When D<0.25 mm,the primary phenomenon was aggregation,which resulted in an increase in MWD.When D<1 mm,the formation of a physical crust on the constructed soil sample surface was facilitated.De-aggregation of aggregates increased the wind erosion rate by an average of 12.31%(M_(4%)),12.21%(M_(8%)),37.15%(M_(12%))and 43.47%(M_(16%))respectively.Conversely,re-aggregation led to a reduction in wind erosion rate by an average of 20.60%(M_(4%)),24.22%(M_(8%)),44.21%(M_(12%))and 34.46%(M_(16%)),respectively.The process of de-aggregation makes the aggregate size smaller,leading to an increase in wind soil erosion losses at the same wind speed.Re-aggregation process showed the opposite tendency.The formation of a crust greatly enhanced the soil surface strength and significantly reduced the degree of wind erosion,which decreased by 0.96%(M_(4%)),14.98%(M_(8%)),79.15%(M_(12%))and 107.23%(M_(16%)),respectively,after crust formation.Although the constructed soil samples formed crusts under different initial soil moisture levels,all samples had naturally air-dried to approximately 4%prior to the wind erosion experimental study was conducted.Therefore,there was no significant change in threshold wind velocity due to different sample moisture levels.In conclusion,we constructed a path model based on the effects of environmental conditions on the wind erosion rate.The results indicated that the initial soil moisture and freeze-thaw effect exerted an indirect influence on wind erosion,by mediating their impact on aggregate variation,MWD,crust strength and crust thickness.The relationship between wind erosion rate and topsoil(2 cm)properties was significant.The initial moisture content and the freeze-thaw effect contributed 30.4%and 49.2%,respectively,to the rate of wind erosion.This study clarifies the role played by the crust and aggregation in the influence of wind erosion under freeze-thaw conditions in the Mollisols region,and provides a scientific theoretical basis for the mechanism of spring wind erosion in cold regions.
基金supported by Guangdong Basic and Applied Basic Research Foundation(2025A1515012147)National Natural Science Foundation of China(12404480)+5 种基金Shenzhen Science and Technology Program(JCYJ20240813113238050,JCYJ20240813113306008)Characteristic Innovation Foundation of Higher Education Institutions of Guangdong Province(2022KTSCX116)Education Department of Guangdong Province(2021KCXTD045)National Natural Science Foundation of China(12274303)Shenzhen Key Laboratory of Applied Technologies of Super-Diamond and Functional Crystals(ZDSYS20230626091303007)National Natural Science Foundation of China(52103202).
文摘In organic solar cells(OSCs),typical methods for fabricating the ternary active layer are blend-casting(BC)or two-step sequential processing(SqP-2T),where all three or at least two components are blended together,which affect the crystallization/aggregation behavior of each other during solid-film formation.Herein,we introduce for the first time a novel three-step sequential processing method,termed SqP-3T,which utilizes hydrocarbon solvents to prepare high-quality ternary active layers.Compared to the SqP-2T and BC techniques,SqP-3T yields an active layer with a higher acceptor ratio on its upper surface and exhibits a longer crystal coherence length in the out-of-plane direction(21.42 A).These characteristics enhance charge transport and collection.Additionally,SqP-3T devices demonstrate nearly a twofold increase in the transient photovoltage decay constant(up to 2.82μs)that is related to carrier lifetime to a certain extent,leading to reduced recombination losses.Consequently,the SqP-3T device achieves a high fill factor(75.67%)and a high short-circuit current density(27.35 mA/cm^(2)),contributing to a power conversion efficiency of 19.2%.These results highlight the potential of SqP-3T or a multi-step sequential deposition process in the production of ternary or multicomponent OSCs,which could be adopted by more material systems in the future.
基金Fundamental Research Program of Shanxi Province (202303021221032, 202403021222292)Key Research and Development (RD) Projects of Shanxi Province (202302150101003)。
文摘Brillouin optical time domain reflectometry(BOTDR)inherently involves a trade-off between sensing range and spatial resolution,particularly in long-distance applications.This paper presents an image-deconvoluted random coding BOTDR approach to simultaneously enhance both sensing range and spatial resolution.In this method,a series of pulses modulated with random codes is employed to extend the sensing range,while the Richardson-Lucy image deconvolution algorithm is applied to refine spatial resolution.The decoding principle for random pulse detection BOTDR is systematically described,and the corresponding point spread function(PSF)is constructed.Numerical simulations are conducted to optimize coding parameters,achieving a simulated spatial resolution of 1 m over a 100 km sensing fiber.The proposed method is experimentally implemented and thoroughly evaluated.The experiment results demonstrate that,without any hardware modifications,the combination of 256-bit random coding with 1oo ns single-code width and image deconvolution extends the sensing range of BOTDR to 100.4 km with a root-mean-square error(RMSE)below 2 MHz,while achieving an actual spatial resolution of 2 m at the fiber end.These findings indicate that the proposed approach can significantly improve both the sensing range and spatial resolution in BOTDR sensing systems.
基金supported by the National Natural Science Foundation of China(nos.91833304,51903032,and 21774047)the Jilin Provincial Science and Technology Department(no.20180201084GX)+3 种基金the Natural Science Foundation of Heilongjiang Province(no.LH2019B002)Postdoctoral Science Foundation of Heilongjiang Province(nos.LBH-TZ1003 and LBH-Z17014)the Open Fund of the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology,no.2021-skllmd)the Fundamental Research Funds for the Central Universities.
文摘Organic light-emitting diodes(OLEDs),which have been recently utilized in some flat-panel display screens such as mobile phones and televisions,show many merits,including light weight,high flexibility,energy preservation,and so forth,and are considered the next-generation displays and solid-state lightings.Blue-emitting materials that can be applied in nondoped OLEDs with little efficiency roll-offs at high brightness are of great importance.Here,a highly efficient,blue-emitting material,9-phenyl10-(4-(pyren-1-yl)phenyl)-9H-pyreno[4,5-d]imidazole(PyPI-Py),is achieved using pyrene[4,5-d]imidazole and pyrene as the weak electron donor and electron acceptor,respectively.The nondoped blue OLED exhibits excellent performance with a maximum brightness of 75,687 cd m^(−2),a maximum current efficiency of 13.38 cd A−1,and a maximum external quantum efficiency(ηext)of 8.52%.Moreover,theηext is maintained at 8.35%and 8.05%at a brightness of 10,000 and 50,000 cd m^(−2),respectively,displaying extremely small efficiency roll-offs of 2.0%and 5.5%.The device characteristics are among the highest values for nondoped blue OLEDs and correspond to the best performance obtained for nondoped pyrene-based blue OLEDs.The superior performance is attributed to the proper donor–acceptor design strategy which results in a quasi-equivalent hybrid local and charge-transfer excited state with the maximum generation of an 82%fraction of singlet excitons.
