Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exc...Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exceedingly high thermal stability is designed and grown.It obtains a cubic lattice system in the temperature range of 80-500 K,accompanied by a completely reversible chromatic variation ranging from yellow to black.Importantly,the intriguing thermochromism is proved to own extremely high reproducibility(over 1000 cycles)without a hysteretic effect,originating from its structural flexibility that including(i)the noteworthy distortion/deformation of[NaCl_(6)]5−and[FeCl_(6)]3−octahedra;(ii)order-disorder arrangement transition of[NaCl_(6)]5−and[FeCl6]3−octahedra as the function of temperature.This study paves the way towards a new class of smart windows and camouflage coatings with an unprecedented colour range based on a Cs_(2)NaFeCl_(6) perovskite.展开更多
Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-b...Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.展开更多
Inorganic halide double perovskites A_(2)B'B"X_(6) have gained significant interests for their diverse composition,stable physicochemical properties,and potential for photoelectric applications.The influences...Inorganic halide double perovskites A_(2)B'B"X_(6) have gained significant interests for their diverse composition,stable physicochemical properties,and potential for photoelectric applications.The influences of trivalent and monovalent cations on the formation energy,decomposition energy,electronic structure and optical properties of cesium-based lead-free Cs^(+)_(2)B'B"Br_(6) (B'=Na^(+),In^(+)Cu^(+),or Ag^(+);B"=Bi^(3),Sb^(3+),In^(3+)) are systematically studied.In view of the analysis and results of the selected double perovskites,for the double perovskites with different B-site trivalent cation,the band gap increases in the order of Cs_(2)AgInBr_(6),Cs_(2)AgSbBr_(6) and Cs_(2)AgBiBr_(6),with Cs_(2)AgBiBr_(6) possessing the highest thermodynamic stability.Therefore,the Bi-based perovskites are further studied to elucidate the effect of monovalent cation on their stability and electronics.Results show that the thermodynamic stability rises in the sequence of Cs_(2)NaBiBr_(6),Cs_(2)InBiBr_(6),Cs_(2)AgBiBr_(6) and Cs_(2)CuBiBr_(6).Notably,Cs_(2)CuBiBr_(6) exhibits a relatively narrow and appropriate band gap of 1.4634 eV,together with the highest absorption coefficient than other compounds,suggesting that Cs_(2)CuBiBr_(6) is a promising light absorbing material that can be further explored experimentally and be applied to optoelectronic devices.Our research offers theoretical backing for the potential optoelectronic application of cesium-based lead-free halide double perovskites in solar energy conversion.展开更多
Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the ...Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the resulted Cs2SnCl6 vacancy-ordered perovskite variant exhibits poor photoluminescence property although it has a direct band gap. Controllable doping is an effective strategy to regulate the optical properties of Cs2SnX6. Herein, combining the first principles calculation and spectral analysis, we attempted to understand the luminescence mechanism of Te4+-doped Cs2SnCl6 lead-free perovskite variants. The chemical potential and defect formation energy are calculated to confirm theoretically the feasible substitutability of tetravalent Te4+ ions in Cs2SnCl6 lattices for the Sn-site. Through analysis of the absorption, emission/excitation, and time-resolved photoluminescence (PL) spectroscopy, the intense green-yellow emission in Te4+:Cs2SnCl6 was considered to originate from the triplet Te(IV) ion 3P1→1S0 STE recombination. Temperature-dependent PL spectra demonstrated the strong electron-phonon coupling that inducing an evident lattice distortion to produce STEs. We further calculated the electronic band structure and molecular orbital levels to reveal the underlying photophysical process. These results will shed light on the doping modulated luminescence properties in stable lead-free Cs2MX6 vacancy-ordered perovskite variants and be helpful to understand the optical properties and physical processes of doped perovskite variants.展开更多
The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite sola...The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite solar cell(PSC)for achieving high power conversion efficiency(PCE).To tackle this problem,we propose the optimization of the energy level alignment by designing and synthesizing novel deep-level hole transport materials(HTMs).The sole introduction of deep-level HTMs successfully reduces the valence band offset between Cs_(2)Ag Bi Br_(6)and HTL,but induces the increased valence band offset at HTL/Au interface,limiting the PCE improvement.To further solve the problem and improve the PCE,the gradient energy level arrangement is constructed by combining the newly developed deep-level HTM 6,6’-(3-((9,9-dimethyl-9H-fluoren-3-yl)(4-methoxyphenyl)amino)thiophene-2,5-diyl)bis(N-(9,9-dimethyl-9H-fluoren-2-yl)-N,9-bis(4-methoxyphenyl)-9H-carbazol-3-amine)(TF)with 2,2’,7,7’-tetrakis(N,N’-dipmethoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD).Through optimization,an impressive PCE of 3.50%with remarkably high open-circuit voltage(V_(oc))and fill factor(FF)is achieved,qualifying it among the best pristine Cs_(2)AgBiBr_(6)PSCs.展开更多
The response speed of the reported Cs_(2)AgBiBr_(6)-based photodetectors exhibits a wide variation ranging from microseconds to nanoseconds,while the reason is still unclear.Apart from the conventional approaches such...The response speed of the reported Cs_(2)AgBiBr_(6)-based photodetectors exhibits a wide variation ranging from microseconds to nanoseconds,while the reason is still unclear.Apart from the conventional approaches such as reducing effective area,new regulating approaches for response speed improvement have rarely been reported.On the other hand,it is generally believed that ultraviolet(UV)light has negative impact on perovskite devices resulting in performance degradation.In this work,we demonstrated that the response speed of the photodetector with FTO/Cs_(2)AgBiBr_(6)/Au structure can be effectively regulated by utilizing UV light-soaking effect without reducing the device area.Particularly,the decay time is efficiently modulated from 30.1μs to 340 ns.In addition,the−3 dB bandwidth of the device is extended from 5 to 20 kHz.It is worth mentioning that the light current is remarkably boosted by 15 times instead of any attenuation.Furthermore,we prove the universality of UV soaking treatment on Cs_(2)AgBiBr_(6)-based photodetectors with other all-inorganic structures,i.e.,FTO/TiO_(2)/Cs_(2)AgBiBr_(6)/Au,FTO/Cs_(2)AgBiBr_(6)/TiO_(2)/Au and FTO/TiO_(2)/Cs_(2)AgBiBr_(6)/CuSCN/Au.Our results demonstrate a new method to improve the response speed and light current of Cs_(2)AgBiBr_(6)-based perovskite all-inorganic photodetectors.展开更多
Near UV highly luminescent colloidal Cs_(2)NaBiCl_(6)nanocrystals(NCs)were synthesized by a simple low-cost ligand-assisted reprecipitation method.In our strategy,metal chloride precursors were added to the mixture of...Near UV highly luminescent colloidal Cs_(2)NaBiCl_(6)nanocrystals(NCs)were synthesized by a simple low-cost ligand-assisted reprecipitation method.In our strategy,metal chloride precursors were added to the mixture of anti-solvent and ligand at room-temperature.The obtained Cs_(2)NaBiCl_(6)NCs exhibited a bright blue emission with significantly improved photoluminescence quantum yield(PLQY)of 39.05%.The optical properties and stability were greatly enhanced by doping Sb where Cs_(2)NaBi_(0.75)Sb_(0.25)Cl_(6)showed a high PLQY of 46.57%,and both the powder and the colloidal solution exhibited superior stability.展开更多
Recently,power conversion efficiency(PCE)of organic-inorganic hybrid perovskite solar cells(PSCs)has been improved to26.1%.However,the toxicity issue of lead still hinders the large-scale commercial production and app...Recently,power conversion efficiency(PCE)of organic-inorganic hybrid perovskite solar cells(PSCs)has been improved to26.1%.However,the toxicity issue of lead still hinders the large-scale commercial production and application of lead(Pb)-based halide perovskites.Fortunately,environmentally friendly tin(Sn)-based perovskites have recently shown excellent performance.Among them,the all-inorganic Sn-based perovskites,including CsSnX_(3) and Cs_(2)SnX_(6),have better stability,more suitable bandgap,and higher charge mobility,which have attracted more attention from researchers than organic-inorganic Sn-based hybrid perovskites.Herein,we review recent research progress on all-inorganic Sn-based perovskite materials and corresponding solar cell devices.Finally,we also summarize the current challenges and future research directions for this type of PSCs.展开更多
Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their pho...Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their photoelectric device performance is still not satisfactory.Herein,we report a facile solution-process method to synthesize the recently most popular lead-free halide double perovskite,MA_(2)Ag Bi Br_(6),and its all-inorganic counterpart,Cs_(2)Ag Bi Br_(6).The obtained MA_(2)Ag Bi Br_(6)and Cs_(2)Ag Bi Br_(6)films exhibit the microplatelet morphology with excellent crystallinity,distinctly contrasting the ones fabricated by the conventional spin-coating method.Once fabricated into simple photodetectors,the Cs_(2)Ag Bi Br_(6)microplatelet devices yield a respectable responsivity of 245 m A W^(-1) that is two orders of magnitude larger than that of the spin-coated films.More importantly,the response speed of the Cs_(2)Ag Bi Br_(6)microplatelets device is as fast as 145μs,which is higher than most of the values reported in the community of halide double perovskites.When subjected to the thermal stability testing,the Cs_(2)Ag Bi Br_(6)microplatelet device can maintain its initial performance after heating to 160℃ and cooling down to room temperature in the ambient environment.All these results suggest that the facile solution-process method is capable of fabricating high-quality lead-free double perovskites,enabling their advanced device applications.展开更多
基金The research was funded by the National Natural Science Foundation of China(No.51802120,51872126,22075103,51672111)Guangdong Basic and Applied Basic Research Foundation for Distinguished Young Scholar(No.2019B151502030)+7 种基金Natural Science Foundation of Guangdong Province(No.2018030310181)the Science and Technology Plan Project of Guangzhou(No.202002030159)Guangdong Basic and Applied Basic Research Foundation for Young Scholar(No.2020A1515111057)‘100 Talents Program of Hebei Province’(No.E2014100008)the Fundamental Research Funds for the Central Universities(No.21619406)X.Y.thanks for the Special Funds for the Cultivation of Guangdong College Students'Scientific and Technological Innovation("Climbing Program"Special Funds)(No.pdjh2019a0055)J.Fan also thanks for the project support for"Young Top talents"in the Pearl River Talent Project of Guangdong Province(2017GC010424)the Guangdong Provincial Innovation and Entrepreneurship Project(grant 2016ZT06D081).
文摘Multifunctional lead-free double perovskites demonstrate remarkable potential towards applications in various fields.Herein,an environmentally-friendly,low-cost,high-throughput Cs_(2)NaFeCl_(6) single crystal with exceedingly high thermal stability is designed and grown.It obtains a cubic lattice system in the temperature range of 80-500 K,accompanied by a completely reversible chromatic variation ranging from yellow to black.Importantly,the intriguing thermochromism is proved to own extremely high reproducibility(over 1000 cycles)without a hysteretic effect,originating from its structural flexibility that including(i)the noteworthy distortion/deformation of[NaCl_(6)]5−and[FeCl_(6)]3−octahedra;(ii)order-disorder arrangement transition of[NaCl_(6)]5−and[FeCl6]3−octahedra as the function of temperature.This study paves the way towards a new class of smart windows and camouflage coatings with an unprecedented colour range based on a Cs_(2)NaFeCl_(6) perovskite.
基金financial support from Macao Science and Technology Development Fund,China(FDCT-0044/2020/A1,FDCT-091/2017/A2,FDCT-014/2017/AMJ)University of Macao Research Grant,China(MYRG2018-00148-IAPME,MYRG2018-00142-IAPME)from University of Macao+2 种基金the Natural Science Foundation of China,China(91733302,61935017)Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials(2019B121205002)Natural Science Foundation of Guangdong Province,China(2019A1515012186).
文摘Lead-free double perovskite Cs_(2)AgBiBr_(6) has gained increasing attention recently.However,the power conversion efficiency(PCE)of Cs_(2)AgBiBr_(6) perovskite solar cells(PSCs)is still low compared with their lead-based counterparts.Here,by using photoluminescence(PL),time-resolved photoluminescence(TRPL),and ultrafast transient absorption(TA)measurements,the unbalance between the electron and hole in diffusion and transfer,which limits the performance of the Cs_(2)AgBiBr_(6) PSCs,was further revealed.Considering this issue,a strategy of using the mesoporous TiO_(2) electron transport layer(ETL)to construct a bulk heterojunction in Cs_(2)AgBiBr_(6) PSCs was proposed.Consequently,the PCE had improved by over 24%comparing with that only used compact TiO_(2) ETL.Moreover,based on mesoporous TiO_(2),the unencapsulated Cs_(2)AgBiBr_(6) PSCs maintained 90%of their initial performance after approximately 1200 h of storage in a desiccator(humidity~30%).This work gives further understanding of Cs_(2)AgBiBr_(6) perovskite and demonstrates that a proper design of balancing the electron and hole diffusion can improve device performance.
基金Funded by the National Natural Science Foundation of China (No.51772228)the Open Fund of Sanya Science and Education Innovation Park (No.2022KF0008)。
文摘Inorganic halide double perovskites A_(2)B'B"X_(6) have gained significant interests for their diverse composition,stable physicochemical properties,and potential for photoelectric applications.The influences of trivalent and monovalent cations on the formation energy,decomposition energy,electronic structure and optical properties of cesium-based lead-free Cs^(+)_(2)B'B"Br_(6) (B'=Na^(+),In^(+)Cu^(+),or Ag^(+);B"=Bi^(3),Sb^(3+),In^(3+)) are systematically studied.In view of the analysis and results of the selected double perovskites,for the double perovskites with different B-site trivalent cation,the band gap increases in the order of Cs_(2)AgInBr_(6),Cs_(2)AgSbBr_(6) and Cs_(2)AgBiBr_(6),with Cs_(2)AgBiBr_(6) possessing the highest thermodynamic stability.Therefore,the Bi-based perovskites are further studied to elucidate the effect of monovalent cation on their stability and electronics.Results show that the thermodynamic stability rises in the sequence of Cs_(2)NaBiBr_(6),Cs_(2)InBiBr_(6),Cs_(2)AgBiBr_(6) and Cs_(2)CuBiBr_(6).Notably,Cs_(2)CuBiBr_(6) exhibits a relatively narrow and appropriate band gap of 1.4634 eV,together with the highest absorption coefficient than other compounds,suggesting that Cs_(2)CuBiBr_(6) is a promising light absorbing material that can be further explored experimentally and be applied to optoelectronic devices.Our research offers theoretical backing for the potential optoelectronic application of cesium-based lead-free halide double perovskites in solar energy conversion.
基金This work was supported by the National Natural Science Foundation of China(Nos.21661010 and 11774134)Guangxi Natural Science Foundation(No.2017GXNSFGA198005)+1 种基金Natural Science Foundation of Hunan Province(No.2020JJ4424)Research Foundation of Education Bureau of Hunan Province(No.18A009)。
文摘Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the resulted Cs2SnCl6 vacancy-ordered perovskite variant exhibits poor photoluminescence property although it has a direct band gap. Controllable doping is an effective strategy to regulate the optical properties of Cs2SnX6. Herein, combining the first principles calculation and spectral analysis, we attempted to understand the luminescence mechanism of Te4+-doped Cs2SnCl6 lead-free perovskite variants. The chemical potential and defect formation energy are calculated to confirm theoretically the feasible substitutability of tetravalent Te4+ ions in Cs2SnCl6 lattices for the Sn-site. Through analysis of the absorption, emission/excitation, and time-resolved photoluminescence (PL) spectroscopy, the intense green-yellow emission in Te4+:Cs2SnCl6 was considered to originate from the triplet Te(IV) ion 3P1→1S0 STE recombination. Temperature-dependent PL spectra demonstrated the strong electron-phonon coupling that inducing an evident lattice distortion to produce STEs. We further calculated the electronic band structure and molecular orbital levels to reveal the underlying photophysical process. These results will shed light on the doping modulated luminescence properties in stable lead-free Cs2MX6 vacancy-ordered perovskite variants and be helpful to understand the optical properties and physical processes of doped perovskite variants.
基金financially supported by the National Natural Science Foundation of China(Nos.22179053,22279046 and 21905119)the Natural Science Excellent Youth Foundation of Jiangsu Provincial(No.BK20220112)+1 种基金the Open Competition Mechanism Project of Carbon Neutrality of Jiangsu Province(No.BE2022026)Zhejiang Province Selected Funding for Postdoctoral Research Projects(No.ZJ2021001)for financial support。
文摘The valence band offset between Cs_(2)AgBiBr_(6)and hole transport layer(HTL)is approximately 1.00 e V,which results in high energy loss and is identified as one of the bottle necks of Cs_(2)Ag BiBr_(6)perovskite solar cell(PSC)for achieving high power conversion efficiency(PCE).To tackle this problem,we propose the optimization of the energy level alignment by designing and synthesizing novel deep-level hole transport materials(HTMs).The sole introduction of deep-level HTMs successfully reduces the valence band offset between Cs_(2)Ag Bi Br_(6)and HTL,but induces the increased valence band offset at HTL/Au interface,limiting the PCE improvement.To further solve the problem and improve the PCE,the gradient energy level arrangement is constructed by combining the newly developed deep-level HTM 6,6’-(3-((9,9-dimethyl-9H-fluoren-3-yl)(4-methoxyphenyl)amino)thiophene-2,5-diyl)bis(N-(9,9-dimethyl-9H-fluoren-2-yl)-N,9-bis(4-methoxyphenyl)-9H-carbazol-3-amine)(TF)with 2,2’,7,7’-tetrakis(N,N’-dipmethoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD).Through optimization,an impressive PCE of 3.50%with remarkably high open-circuit voltage(V_(oc))and fill factor(FF)is achieved,qualifying it among the best pristine Cs_(2)AgBiBr_(6)PSCs.
基金supported by the National Natural Science Foundation of China(51772135 and 52002148)the Ministry of Education of China(6141A02022516)+2 种基金the Fundamental Research Funds for the Central Universities(11619103)Guangdong Basic and Applied Basic Research Foundation(2020A1515011377)the support from China and Germany Postdoctoral Exchange Programthe financial support from Agency for Science,Technology,and Research(A*STAR),Singapore by the AME Individual Research Grants(A1883c0004)。
文摘The response speed of the reported Cs_(2)AgBiBr_(6)-based photodetectors exhibits a wide variation ranging from microseconds to nanoseconds,while the reason is still unclear.Apart from the conventional approaches such as reducing effective area,new regulating approaches for response speed improvement have rarely been reported.On the other hand,it is generally believed that ultraviolet(UV)light has negative impact on perovskite devices resulting in performance degradation.In this work,we demonstrated that the response speed of the photodetector with FTO/Cs_(2)AgBiBr_(6)/Au structure can be effectively regulated by utilizing UV light-soaking effect without reducing the device area.Particularly,the decay time is efficiently modulated from 30.1μs to 340 ns.In addition,the−3 dB bandwidth of the device is extended from 5 to 20 kHz.It is worth mentioning that the light current is remarkably boosted by 15 times instead of any attenuation.Furthermore,we prove the universality of UV soaking treatment on Cs_(2)AgBiBr_(6)-based photodetectors with other all-inorganic structures,i.e.,FTO/TiO_(2)/Cs_(2)AgBiBr_(6)/Au,FTO/Cs_(2)AgBiBr_(6)/TiO_(2)/Au and FTO/TiO_(2)/Cs_(2)AgBiBr_(6)/CuSCN/Au.Our results demonstrate a new method to improve the response speed and light current of Cs_(2)AgBiBr_(6)-based perovskite all-inorganic photodetectors.
基金sponsored by the National Natural Science Foundation of China(Nos.21475021,21427807 and 21777096)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Near UV highly luminescent colloidal Cs_(2)NaBiCl_(6)nanocrystals(NCs)were synthesized by a simple low-cost ligand-assisted reprecipitation method.In our strategy,metal chloride precursors were added to the mixture of anti-solvent and ligand at room-temperature.The obtained Cs_(2)NaBiCl_(6)NCs exhibited a bright blue emission with significantly improved photoluminescence quantum yield(PLQY)of 39.05%.The optical properties and stability were greatly enhanced by doping Sb where Cs_(2)NaBi_(0.75)Sb_(0.25)Cl_(6)showed a high PLQY of 46.57%,and both the powder and the colloidal solution exhibited superior stability.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX19_0932)。
文摘Recently,power conversion efficiency(PCE)of organic-inorganic hybrid perovskite solar cells(PSCs)has been improved to26.1%.However,the toxicity issue of lead still hinders the large-scale commercial production and application of lead(Pb)-based halide perovskites.Fortunately,environmentally friendly tin(Sn)-based perovskites have recently shown excellent performance.Among them,the all-inorganic Sn-based perovskites,including CsSnX_(3) and Cs_(2)SnX_(6),have better stability,more suitable bandgap,and higher charge mobility,which have attracted more attention from researchers than organic-inorganic Sn-based hybrid perovskites.Herein,we review recent research progress on all-inorganic Sn-based perovskite materials and corresponding solar cell devices.Finally,we also summarize the current challenges and future research directions for this type of PSCs.
基金financially supported by the Research Fellow Scheme(RFS2021-1S04)the Theme-based Research(T42-103/16-N)of the Research Grants Council of Hong Kong SAR,ChinaFoshan Innovative and Entrepreneurial Research Team Program(2018IT100031)。
文摘Due to the better stability and environmentfriendly nature,lead-free halide double perovskites are widely explored as promising materials for next-generation photovoltaics and optoelectronics;however,to date,their photoelectric device performance is still not satisfactory.Herein,we report a facile solution-process method to synthesize the recently most popular lead-free halide double perovskite,MA_(2)Ag Bi Br_(6),and its all-inorganic counterpart,Cs_(2)Ag Bi Br_(6).The obtained MA_(2)Ag Bi Br_(6)and Cs_(2)Ag Bi Br_(6)films exhibit the microplatelet morphology with excellent crystallinity,distinctly contrasting the ones fabricated by the conventional spin-coating method.Once fabricated into simple photodetectors,the Cs_(2)Ag Bi Br_(6)microplatelet devices yield a respectable responsivity of 245 m A W^(-1) that is two orders of magnitude larger than that of the spin-coated films.More importantly,the response speed of the Cs_(2)Ag Bi Br_(6)microplatelets device is as fast as 145μs,which is higher than most of the values reported in the community of halide double perovskites.When subjected to the thermal stability testing,the Cs_(2)Ag Bi Br_(6)microplatelet device can maintain its initial performance after heating to 160℃ and cooling down to room temperature in the ambient environment.All these results suggest that the facile solution-process method is capable of fabricating high-quality lead-free double perovskites,enabling their advanced device applications.
