Because of the good thermal stability and superior carrier transport characteristics of formamidinium lead trihalide perovskite HC(NH_2)_2 PbX_3(FAPbX_3), it has been considered to be a better optoelectronic material ...Because of the good thermal stability and superior carrier transport characteristics of formamidinium lead trihalide perovskite HC(NH_2)_2 PbX_3(FAPbX_3), it has been considered to be a better optoelectronic material than conventional CH_3NH_3-PbX_3(MAPbX_3). Herein, we fabricated a FAPbBr_3 microcrystal-based photodetector that exhibited a good responsivity of 4000 A W-1 and external quantum efficiency up to 106% under one-photon excitation, corresponding to the detectivity greater than 1014 Jones. The responsivity is two orders of magnitude higher than that of previously reported formamidinium perovskite photodetectors. Furthermore, the FAPbBr_3 photodetector's responsivity to two-photon absorption with an 800-nm excitation source can reach 0.07 A W^(-1), which is four orders of magnitude higher than that of its MAPbBr_3 counterparts. The response time of this photodetector is less than 1 ms.This study provides solid evidence that FAPbBr_3 can be an excellent candidate for highly sensitive and fast photodetectors.展开更多
Maximizing ultrafast electron-transfer kinetics in semiconductor is pivotal but challenging for highefficiency solar-to-energy during the photocatalytic reaction process due to the intrinsic property of photocatalysts...Maximizing ultrafast electron-transfer kinetics in semiconductor is pivotal but challenging for highefficiency solar-to-energy during the photocatalytic reaction process due to the intrinsic property of photocatalysts with low surface electron density.Herein,a model photocatalyst CdS@Mo is synthesized through a typical hydrothermal method for modulating the ultrafast electron-transfer to enhance the surface electron density.X-ray absorption fine spectra(XAFS)reveal that Mo is coordinated with S atoms to form a Mo-S_(6) configuration which is different from common MoS_(2) and Mo foil structures.Based on the femtosecond transient absorption spectra(fs-TAS),it is found that the formation of Mo-S6 configuration contributes to the fast decay of CdS signal and Mo-S_(6) signal reactivation,illustrating the ultrafast electron-transfer(∼2.2 ps)from CdS to Mo-S_(6) configuration,which achieves the enhanced electron density of photocatalyst surface.Finally,a holistic photocatalytic performance evaluation discloses that the growing of Mo-S_(6) configuration obviously improves the photocatalytic hydrogen evolution(PHE)effi-ciency of CdS from 28.5 to 47.5 mmol g^(-1)h^(-1)with a solar-to-hydrogen(STH)efficiency of 0.10%which is seldomly discussed in the system containing sacrificial agents.This work opens a new path to modulate the surface electron density by tuning the ultrafast electron-transfer for enhancing reaction efficiency in electron-density-dependent systems.展开更多
Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable.However,compared to the lead perovskites,their optoelectronic properties are compromised.He...Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable.However,compared to the lead perovskites,their optoelectronic properties are compromised.Herein we report a series of bulk lead-free mixed Bi-In halide double perovskites:Cs2AgBi1-xInxCl6(0<x<1).The Cs2AgBi0.125In0.875Cl6breaks the parity-forbidden transition and retains direct band gap structure,having warm-white light emission,with photoluminescence quantum efficiency(PLQE)of 70.3%,much higher than the PLQE of reported lead perovskite materials.Its exciton self-trapping dynamics is investigated.Meanwhile,the Cs2AgBi0.125In0.875Cl6nanocrystals and Cs2AgBi0.125In0.875Cl6microcrystals can be synthesized by modified hot injection and rapid cooling crystallization,respectively.The size effect of Cs2AgBi0.125In0.875Cl6is studied on the photoluminescence(PL)property.Additionally,the bulk material exhibits excellent stability on exposure to light,humidity and air for more than 3 months.It is a promising candidate as highly efficient warm white-light emitting material for road lighting.展开更多
Multiple morphologies of colloidal perovskite nanocrystals(NCs)diversify their optical and electronic properties.Among them,the linear absorption cross-section(σ)is a primary parameter to determine their intrinsic ph...Multiple morphologies of colloidal perovskite nanocrystals(NCs)diversify their optical and electronic properties.Among them,the linear absorption cross-section(σ)is a primary parameter to determine their intrinsic photophysical features,and consequently,application potential.Herein,three morphologies of all-inorganic hybrid colloidal perovskite CsPbBr_(3)NCs,nanocubes(NBs),nanoplatelets(NLs),and nanowires(NWs),were targeted,and their linearσvalues were obtained through femtosecond transient absorption(TA)spectroscopy analysis.At high excitation energy well above the bandgap,theσper particle of all CsPbBr3 NCs linearly increased with the particle volume(VNC)regardless of the morphology with the value ofσ400=9.45×10^(4)cm^(−1)×VNC(cm^(2)).Density functional theory(DFT)calculation confirmed the negligible influence of shapes on the optical selection rules.The Einstein spontaneous emission coefficients calculated from theσvalues define the intrinsic radiative recombination rate.However,reduced size dependence is observed when the excitation energy is close to the bandgap(i.e.,at 460 nm)with the value ofσ460=2.82×10^(8)cm0.65×(VNC)0.45(cm^(2)).This should be ascribed to the discrete energy levels as well as lower density of states close to the band edge for perovskite NCs.These results provide in-depth insight into the optical characteristics for perovskite NCs.展开更多
Photocatalysis plays a crucial role in harnessing renewable energy by efficiently converting solar energy into chemical energy.Adequate cognition of photogenerated charge carrier dynamics in photocatalysis is the key ...Photocatalysis plays a crucial role in harnessing renewable energy by efficiently converting solar energy into chemical energy.Adequate cognition of photogenerated charge carrier dynamics in photocatalysis is the key to realizing efficient solar energy utilization,and provides guidance for breaking through the efficiency bottleneck.However,a convincing correlation between those photophysical processes and the photocatalytic performance has yet been established due to the complexity of photocatalytic reactions.In this review,we overviewed the detailed ultrafast photophysics in photocatalysis based on three typical ultrafast spectroscopic techniques(TRPL,TA and TRIR),and put a special focus on the justification as well as the limitation on correlating those photophysics with the actual catalytic performance.The classification of carrier behaviors after photoexcitation as well as typical time-resolved spectroscopic characterization techniques are briefly introduced first.State-of-the-art studies on the excited state dynamics in photocatalysis and its correlation to catalytic performance are then systematically presented from three types of common photocatalysts including quantum dots,polymeric photocatalysts,and traditional semiconductors.Finally,a summary on the correlation between ultrafast photophysics and the final photocatalytic performance is provided,and challenges and limitations of current photophysical characterization to rationalize the catalytic performance are outlined.展开更多
基金the National Key R@D Program of China (Grant 2017YFA0204800)the National Natural Science Foundation of China (Grant Nos: 21533010, 21321091, 21525315, 91333116 and 21173169) for their financial supports
文摘Because of the good thermal stability and superior carrier transport characteristics of formamidinium lead trihalide perovskite HC(NH_2)_2 PbX_3(FAPbX_3), it has been considered to be a better optoelectronic material than conventional CH_3NH_3-PbX_3(MAPbX_3). Herein, we fabricated a FAPbBr_3 microcrystal-based photodetector that exhibited a good responsivity of 4000 A W-1 and external quantum efficiency up to 106% under one-photon excitation, corresponding to the detectivity greater than 1014 Jones. The responsivity is two orders of magnitude higher than that of previously reported formamidinium perovskite photodetectors. Furthermore, the FAPbBr_3 photodetector's responsivity to two-photon absorption with an 800-nm excitation source can reach 0.07 A W^(-1), which is four orders of magnitude higher than that of its MAPbBr_3 counterparts. The response time of this photodetector is less than 1 ms.This study provides solid evidence that FAPbBr_3 can be an excellent candidate for highly sensitive and fast photodetectors.
基金The National Natural Science Foundation of China(Nos.22178291,22209135,22002123,and 22311530118)the National Science Fund for the Distinguished Young Scholars(No.52325401)。
文摘Maximizing ultrafast electron-transfer kinetics in semiconductor is pivotal but challenging for highefficiency solar-to-energy during the photocatalytic reaction process due to the intrinsic property of photocatalysts with low surface electron density.Herein,a model photocatalyst CdS@Mo is synthesized through a typical hydrothermal method for modulating the ultrafast electron-transfer to enhance the surface electron density.X-ray absorption fine spectra(XAFS)reveal that Mo is coordinated with S atoms to form a Mo-S_(6) configuration which is different from common MoS_(2) and Mo foil structures.Based on the femtosecond transient absorption spectra(fs-TAS),it is found that the formation of Mo-S6 configuration contributes to the fast decay of CdS signal and Mo-S_(6) signal reactivation,illustrating the ultrafast electron-transfer(∼2.2 ps)from CdS to Mo-S_(6) configuration,which achieves the enhanced electron density of photocatalyst surface.Finally,a holistic photocatalytic performance evaluation discloses that the growing of Mo-S_(6) configuration obviously improves the photocatalytic hydrogen evolution(PHE)effi-ciency of CdS from 28.5 to 47.5 mmol g^(-1)h^(-1)with a solar-to-hydrogen(STH)efficiency of 0.10%which is seldomly discussed in the system containing sacrificial agents.This work opens a new path to modulate the surface electron density by tuning the ultrafast electron-transfer for enhancing reaction efficiency in electron-density-dependent systems.
基金supported by the National Natural Science Foundation of China (21533010, 21525315)the National Key Research and Development Program of China (2017YFA0204800)+2 种基金DICP DMTO201601DICP ZZBS201703the Science Challenging Program (JCKY2016212A501)
文摘Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable.However,compared to the lead perovskites,their optoelectronic properties are compromised.Herein we report a series of bulk lead-free mixed Bi-In halide double perovskites:Cs2AgBi1-xInxCl6(0<x<1).The Cs2AgBi0.125In0.875Cl6breaks the parity-forbidden transition and retains direct band gap structure,having warm-white light emission,with photoluminescence quantum efficiency(PLQE)of 70.3%,much higher than the PLQE of reported lead perovskite materials.Its exciton self-trapping dynamics is investigated.Meanwhile,the Cs2AgBi0.125In0.875Cl6nanocrystals and Cs2AgBi0.125In0.875Cl6microcrystals can be synthesized by modified hot injection and rapid cooling crystallization,respectively.The size effect of Cs2AgBi0.125In0.875Cl6is studied on the photoluminescence(PL)property.Additionally,the bulk material exhibits excellent stability on exposure to light,humidity and air for more than 3 months.It is a promising candidate as highly efficient warm white-light emitting material for road lighting.
基金supported by the National Natural Science Foundation of China (NSFC, U1862111)China Scholarship Council (201706990062)+4 种基金Independent Research Fund Denmark-Nature Sciences (DFF-7014-00302)Independent Research Fund Denmark-Sapere Aude starting grant (7026-00037A)Swedish Research Council VR starting grant (2017-05337), grants VR2018-06011, and VR201805090the Research Fund for international Young Scientists from NSFC, China (21950410515)Swedish Energy Agency
文摘Multiple morphologies of colloidal perovskite nanocrystals(NCs)diversify their optical and electronic properties.Among them,the linear absorption cross-section(σ)is a primary parameter to determine their intrinsic photophysical features,and consequently,application potential.Herein,three morphologies of all-inorganic hybrid colloidal perovskite CsPbBr_(3)NCs,nanocubes(NBs),nanoplatelets(NLs),and nanowires(NWs),were targeted,and their linearσvalues were obtained through femtosecond transient absorption(TA)spectroscopy analysis.At high excitation energy well above the bandgap,theσper particle of all CsPbBr3 NCs linearly increased with the particle volume(VNC)regardless of the morphology with the value ofσ400=9.45×10^(4)cm^(−1)×VNC(cm^(2)).Density functional theory(DFT)calculation confirmed the negligible influence of shapes on the optical selection rules.The Einstein spontaneous emission coefficients calculated from theσvalues define the intrinsic radiative recombination rate.However,reduced size dependence is observed when the excitation energy is close to the bandgap(i.e.,at 460 nm)with the value ofσ460=2.82×10^(8)cm0.65×(VNC)0.45(cm^(2)).This should be ascribed to the discrete energy levels as well as lower density of states close to the band edge for perovskite NCs.These results provide in-depth insight into the optical characteristics for perovskite NCs.
基金supported by the National Science Fund for Distinguished Young Scholars(52325401)the National Key R&D Project of China(2020YFA0710000)+7 种基金the National Natural Science Foundation of China(22178291,22309152,22311530118,22209135)the National High-end Foreign Experts Recruitment Program(G2022036015L)the Sichuan High-end Foreign Experts Recruitment Program(23RCYJ0029)the International Science and Technology Cooperation project of Chengdu(2021-GH02-00052-HZ)Special Project for the Central Government to Guide the Development of Local Science and Technology in Sichuan Province(22ZYZYTS0231)the Scientific Research Starting Project of SWPU(2021QHZ028)Swedish Foundation for International Cooperation in Research and Higher Education(STINT,CH2019-8179)support from research grant(VIL50350)from VILLUM FONDEN,Denmark,and Swedish Research Council(2021-05319).
文摘Photocatalysis plays a crucial role in harnessing renewable energy by efficiently converting solar energy into chemical energy.Adequate cognition of photogenerated charge carrier dynamics in photocatalysis is the key to realizing efficient solar energy utilization,and provides guidance for breaking through the efficiency bottleneck.However,a convincing correlation between those photophysical processes and the photocatalytic performance has yet been established due to the complexity of photocatalytic reactions.In this review,we overviewed the detailed ultrafast photophysics in photocatalysis based on three typical ultrafast spectroscopic techniques(TRPL,TA and TRIR),and put a special focus on the justification as well as the limitation on correlating those photophysics with the actual catalytic performance.The classification of carrier behaviors after photoexcitation as well as typical time-resolved spectroscopic characterization techniques are briefly introduced first.State-of-the-art studies on the excited state dynamics in photocatalysis and its correlation to catalytic performance are then systematically presented from three types of common photocatalysts including quantum dots,polymeric photocatalysts,and traditional semiconductors.Finally,a summary on the correlation between ultrafast photophysics and the final photocatalytic performance is provided,and challenges and limitations of current photophysical characterization to rationalize the catalytic performance are outlined.
