BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfacto...BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.展开更多
Lead-free double perovskite halides are emerging optoelectronic materials that are alternatives to leadbased perovskite halides.Recently,single-crystalline double perovskite halides were synthesized,and their intrigui...Lead-free double perovskite halides are emerging optoelectronic materials that are alternatives to leadbased perovskite halides.Recently,single-crystalline double perovskite halides were synthesized,and their intriguing functional properties were demonstrated.Despite such pioneering works,lead-free double perovskite halides with better crystallinity are still in demand for applications to novel optoelectronic devices.Here,we realized highly crystalline Cs2AgBiBr6 single crystals with a well-defined atomic ordering on the microscopic scale.We avoided the formation of Ag vacancies and the subsequent secondary Cs3Bi2Br9 by manipulating the initial chemical environments in hydrothermal synthesis.The suppression of Ag vacancies allows us to reduce the trap density in the as-grown crystals and to enhance the carrier mobility further.Our design strategy is applicable for fabricating other lead-free halide materials with high crystallinity.展开更多
基金supported by the program of Future Hydrogen Original Technology Development(2021M3I3A1084747),through the National Research Foundation of Korea(NRF)funded by the Korean government(Ministry of Science and ICT(MSIT))by the NRF grant funded by the Korea government(MSIT)(No.2020R1A2C1005590)。
文摘BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.
基金the National Research Foundation of Korea(NRF)grants funded by the Ministry of Science and ICT(NRF-2020R1F1A1057220)the Ministry of Education(NRF-2019R1A6A1A11053838)+4 种基金C.W.A acknowledges the support by Basic Science Research Program through the NRF funded the Ministry of Science and ICT(NRF-2018R1A2B6009210)Y.H.H.acknowledges the support by the NRF of Korea(NRF-2019R1I1A3A01063856)H.Y.J.acknowledges the support from Creative Materials Discovery Program(NRF-2016M3D1A1900035)Y.-H.S.acknowledges the support by Basic Science Research Programthrough the NRF funded the Ministry of Science and ICT(NRF-2018R1A2B6005159)Experiments at PLS-II were supported in part by MSICT and POSTECH.
文摘Lead-free double perovskite halides are emerging optoelectronic materials that are alternatives to leadbased perovskite halides.Recently,single-crystalline double perovskite halides were synthesized,and their intriguing functional properties were demonstrated.Despite such pioneering works,lead-free double perovskite halides with better crystallinity are still in demand for applications to novel optoelectronic devices.Here,we realized highly crystalline Cs2AgBiBr6 single crystals with a well-defined atomic ordering on the microscopic scale.We avoided the formation of Ag vacancies and the subsequent secondary Cs3Bi2Br9 by manipulating the initial chemical environments in hydrothermal synthesis.The suppression of Ag vacancies allows us to reduce the trap density in the as-grown crystals and to enhance the carrier mobility further.Our design strategy is applicable for fabricating other lead-free halide materials with high crystallinity.
