Surface passivation via post-treatment with organic reagents is a popular strategy to improve the stability and efficiency of perovskite solar cell. However, organic passivation still suffers from the weak bonding bet...Surface passivation via post-treatment with organic reagents is a popular strategy to improve the stability and efficiency of perovskite solar cell. However, organic passivation still suffers from the weak bonding between organic chemicals and perovskite layers. Here we reported a facile inorganic layer passivating method containing strong Pb–S bonding by using ammonium sulfide treatment. A compact PbS_x layer was in-situ formed on the top surface of the perovskite film, which could passivate and protect the perovskite surface to enhance the performance and stability. Our novel inorganic passivation layer strategy demonstrates great potential for the development of high efficiency hybrid and robust perovskite optoelectronics.展开更多
The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are...The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are identified as crucial solutions. Organic perovskites MAPbI<sub>3</sub> and FAPbI<sub>3</sub>, characterized by their abundance, low cost, and ease of synthesis, are emerging as candidates for study to enhance their competitiveness. It is within this framework that this article presents a comparative analysis of the performances of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites in the context of photovoltaic devices. The analysis focuses on the optoelectronic characteristics and stability of these high-potential materials. The optical properties of perovskites are rigorously evaluated, including band gaps, photoluminescence, and light absorption, using UV-Vis spectroscopy and photoluminescence techniques. The crystal structure is characterized by X-ray diffraction, while film morphology is examined through scanning electron microscopy. The results reveal significant variations between the two types of perovskites, directly impacting the performance of resulting solar devices. Simultaneously, the stability of perovskites is subjected to a thorough study, exposing the materials to various environmental conditions, highlighting key determinants of their durability. Films of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> demonstrate distinct differences in terms of topography, optical performance, and stability. Research has unveiled that planar perovskite solar cells based on FAPbI<sub>3</sub> offer higher photoelectric conversion efficiency, surpassing their MAPbI<sub>3</sub>-based counterparts in terms of performance. These advancements aim to overcome stability constraints and enhance the long-term durability of perovskites, ultimately aiming for practical application of these materials. This comprehensive comparative analysis provides an enlightened understanding of the optoelectronic performance and stability of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites, which is critically important to guide future research and development of solar devices that are both more efficient and sustainable.展开更多
Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the rela...Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the relationship between the interfacial structure and electronic properties of these heterojunctions at the atomic scale.Access to such knowledge is critical for guiding the design and enhancing the efficiency of novel photocatalyst classes.Herein,a first-principles computational investigation focuses on the interfacial geometry,electronic structure and electron transfer mechanisms of MAPbI3/α-Fe_(2)O_(3),MAPbI3/γ-Fe_(2)O_(3) and MAPbI3/TiO_(2) heterojunctions.Compared to the classical MAPbI3/TiO_(2) system,the influence of iron coordination at the two octahedral iron sites ofα-Fe_(2)O_(3) and at both tetrahedral and octahedral iron sites ofγ-Fe_(2)O_(3) is investigated.This indicates that the stability of the interface on theγ-Fe_(2)O_(3)(111)surface is enhanced by the octahedrally coordinated iron,whereas the subsurface Fe_(o2) plays a pivotal role in stabilizing the interface with PbI on theα-Fe_(2)O_(3)-Fe_(o1) surface.Furthermore,a notable modulation by different iron coordinations of the valence band maximum charge distribution at theα-Fe_(2)O_(3)/PbI andγ-Fe_(2)O_(3)/PbI interfaces is observed,which is pivotal for the separation and transfer of photogenerated electrons and holes.Combined with the comprehensive analysis of the band structure,electrostatic potential and average plane charge density of the heterojunction,the MAPbI3/iron oxide heterojunction is consistent with the S-scheme heterojunction mechanism.Molecular adsorption simulations of CO_(2),O_(2) and H_(2)O show that theα-Fe_(2)O_(3)-Fe_(o1)/PbI interface stands out with the lowest adsorption energy,indicating its superior photocatalytic potential for CO_(2) reduction and dye degradation.These findings provide valuable insights into the design principles of photocatalytic materials,emphasizing the strategic manipulation of iron coordination to optimize iron-based heterojunction performance.展开更多
Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a signi...Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a significant increase in grain size to 29.64 nm,alongside reductions in dislocation line density to 5.39×1014 m−2 and d-spacing to 3.18Å,while maintaining the native cubic crystal structure of MAPbI2Br.This research demonstrates a reduction in deep-level trap states with Ag doping,along with a significant narrowing of the band gap to 1.91 eV in the 6%Ag-doped MAPbI2Br.Moreover,the refractive index and extinction coefficient increased to 2.54 and 2.13,respectively.Regarding solar cell performance,all cells demonstrated encouraging outcomes;still,the 6%Ag-doped cell distinguished itself with a fill factor of 0.82,an open-circuit voltage of 1.07 V,an outstanding short-circuit current density of 11.31 mA/cm²,and an efficiency of 10.03%.These results highlight the effectiveness of Ag doping in improving perovskite solar cell technology,marking a notable progress in this field.展开更多
Time-of-flight(ToF)transient current method is an important technique to study the transport characteristics of semiconductors.Here,both the direct current(DC)and pulsed bias ToF transient current method are employed ...Time-of-flight(ToF)transient current method is an important technique to study the transport characteristics of semiconductors.Here,both the direct current(DC)and pulsed bias ToF transient current method are employed to investigate the transport properties and electric field distribution inside the MAPbI_(3) single crystal detector.Owing to the almost homogeneous electric field built inside the detector during pulsed bias ToF measurement,the free hole mobility can be directly calculated to be about 22 cm^(2)·V^(-1)·s^(-1),and the hole lifetime is around 6.5μs–17.5μs.Hence,the mobility-lifetime product can be derived to be 1.4×10^(-4)cm^(2)·V^(-1)–3.9×10^(-4)cm^(2)·V^(-1).The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulsed bias,which arises mainly from the inhomogeneous electric field distribution inside the perovskite.The positive space charge density can then be deduced to increase from 3.1×10^(10)cm^(-3)to 6.89×10^(10)cm^(-3)in a bias range of 50 V–150 V.The ToF measurement can provide us with a facile way to accurately measure the transport properties of the perovskite single crystals,and is also helpful in obtaining a rough picture of the internal electric field distribution.展开更多
The ability of methylammonium lead triiodide(MAPbI3)to achieve photoelectric conversion efficiency that is on par with crystalline silicon has led to a surge of interest in perovskite photovoltaics.However,an in-depth...The ability of methylammonium lead triiodide(MAPbI3)to achieve photoelectric conversion efficiency that is on par with crystalline silicon has led to a surge of interest in perovskite photovoltaics.However,an in-depth understanding of how the ubiquitous coupling between the fast rovibrational movements of the organic cations and the phonon vibrations of the inorganic framework affects the relaxation and recombination of hot carriers remains largely elusive.Access to such knowledge is critical to guide design and increase efficiency of new classes of perovskite solar cells.We report a time-domain ab initio investigation of temperature dependent excited state dynamics in MAPbI3,with particular emphasis on nuclear anharmonic effects.The observed strong anharmonicity is attributed to softness of the material and unusual dynamical coupling between the organic and inorganic components.At an elevated temperature,the hydrogen bonding between MA and iodines is weakened,enhancing rotation of MA cations,which become more dynamically disordered.As a result,thermal vibrations of the inorganic Pb-Ⅰ sublattice are suppressed,and the lattice anharmonicity is decreased.Thermal fluctuations of the electronic energy levels are found to follow the trend of anharmonic motions of Pb and I atoms,with holes relaxing faster to the band edges than electrons,due to higher density of the hole states.While elevated temperature accelerates intraband carrier cooling,it slows nonradiative carrier recombination.The latter result is important for performance,since solar cells and other devices heat up during operation.The reported signatures of coupled structural dynamics of the organic cations and inorganic framework unravel the interplay between anomalous structural fluctuations and charge carrier dynamics,which is of particular importance for fundamental understanding of the structure-property relationships in hybrid metal halide perovskites.展开更多
Hybrid organic–inorganic perovskites are promising for optoelectronic applications,yet the impact of intrinsic defects on hot carrier dynamics remains poorly understood.Here,we investigate hot carrier dynamics in met...Hybrid organic–inorganic perovskites are promising for optoelectronic applications,yet the impact of intrinsic defects on hot carrier dynamics remains poorly understood.Here,we investigate hot carrier dynamics in methylammonium lead triiodide(MAPbI_(3))perovskite containing Pb vacancies,a prevalent defect type,using ab initio nonadiabatic molecular dynamics.We observe pronounced slower hot carrier cooling in Pb vacancy-containing MAPbI_(3)compared to pristine system.In particular,the hot hole cooling in the Pb vacancy system is approximately an order of magnitude slower than that of pristine perovskite for states situated∼0.5 eV below the top of the valence bands.This deceleration arises primarily from reduced nonadiabatic couplings due to charge state localization and suppressed fluctuations of the inorganic sub-lattice,facilitated by the enhanced rotational disorder of MA cations in the presence of Pb vacancies.Additionally,Pb vacancies introduce intraband defect states capable of trapping photogenerated hot holes,further delaying the hot carrier cooling process.The absence of trap-assisted hot carrier cooling dynamics in hybrid perovskite is consistent with the well-established consensus of defect tolerance in these materials.Our findings provide crucial insights into defect-mediated hot carrier dynamics in hybrid perovskites,holding significant implications for advancing the development of perovskite solar cells and related devices through defect engineering.展开更多
Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a signi...Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a significant increase in grain size to 29.64 nm,alongside reductions in dislocation line density to 5.39×1014 m−2 and d-spacing to 3.18Å,while maintaining the native cubic crystal structure of MAPbI2Br.This research demonstrates a reduction in deep-level trap states with Ag doping,along with a significant narrowing of the band gap to 1.91 eV in the 6%Ag-doped MAPbI2Br.Moreover,the refractive index and extinction coefficient increased to 2.54 and 2.13,respectively.Regarding solar cell performance,all cells demonstrated encouraging outcomes;still,the 6%Ag-doped cell distinguished itself with a fill factor of 0.82,an open-circuit voltage of 1.07 V,an outstanding short-circuit current density of 11.31 mA/cm²,and an efficiency of 10.03%.These results highlight the effectiveness of Ag doping in improving perovskite solar cell technology,marking a notable progress in this field.展开更多
The strong coupling between photons and phonons in polar materials gives rise to phonon-polaritons that encapsulate a wealth of physical information,offering crucial tools for the ultrafast terahertz sources and the t...The strong coupling between photons and phonons in polar materials gives rise to phonon-polaritons that encapsulate a wealth of physical information,offering crucial tools for the ultrafast terahertz sources and the topological engineering of terahertz light.However,it is still quite challenging to form and manipulate the terahertz phonon-polaritons under the ultrastrong coupling regime till now.In this work,we demonstrate the ultrastrong coupling between the phonon(at 0.95 THz)in a MAPbI3 film and the metallic bound states in the continuum(BICs)in Au metasurfaces.The Rabi splitting can be continuously tuned from 28%to 48.4%of the phonon frequency by adjusting the parameters(size,shape and period)of Au metasurfaces,reaching the ultrastrong coupling regime.By introducing wavelet transform,the mode evolution information of the terahertz phonon-polariton is successfully extracted.It indicates that the phonon radiation intensity of the MAPbI_(3)film is enhanced as the coupling strength is increased.This work not only establishes a new platform for terahertz devices but also opens new avenues for exploring the intricate dynamics of terahertz phonon-polaritons.展开更多
Organic–inorganic hybrid perovskites are quite promising candidates in the field of electromagnetic wave (EMW) absorption due to their unique physicochemical properties. However, it is still a considerable challenge ...Organic–inorganic hybrid perovskites are quite promising candidates in the field of electromagnetic wave (EMW) absorption due to their unique physicochemical properties. However, it is still a considerable challenge to satisfy the light weight, broad bandwidth, and strong absorption properties simultaneously. Herein, the solution of methylammonium lead iodide (MAPbI3) perovskites was infiltrated into the pores of reduced graphene oxide (rGO) aerogels. After drying, a series of MAPbI3/rGO composite aerogel (MGA) materials were synthesized by anchoring the MAPbI3 perovskite nanoparticles to rGO sheets with the assistance of rGO templates. Through the adjustment of component ratios, excellent EMW absorption properties are obtained with the synergistic effects of polarization loss, conduction loss, and multiple reflection and scattering of MAPbI3 and rGO. The porous structure of the aerogel and the suitable group distribution ratio allowed the MGA-4 samples to obtain excellent impedance matching and ultra-low density of ∼ 7.69 mg·cm−3. At a low filling ratio of 15 wt.%, the MGA-4 sample simultaneously achieves highly efficient and broadband EMW absorption performance at a thin thickness. The MGA-4 sample obtained a minimum reflection loss value of −64.35 dB and the effective absorption bandwidth (EAB) value of 5.4 GHz at a thickness of 2.08 mm and a maximum EAB (EABmax) value of 6.2 GHz under 2.22 mm. The MGA-5 sample obtained a maximum EAB value of 6.4 GHz with the thinckness of 2.16 mm. Furthermore, the simulation results of the radar cross-section (RCS) verified the component-optimized composites are capable of achieving excellent EMW attenuation. This paper provides a new approach and valuable reference for the development of hybrid perovskite-based microwave absorption materials with lightweight, ultra-broadband, and strong absorption properties.展开更多
基金the support of the NSFC (Grant 21777096 and 51861145101)Huoyingdong Grant (151046)+1 种基金the support of the Initiative Postdocs Supporting Program (Grant No.BX20180185)China Postdoctoral Science Foundation (Grant No.2018M640387)。
文摘Surface passivation via post-treatment with organic reagents is a popular strategy to improve the stability and efficiency of perovskite solar cell. However, organic passivation still suffers from the weak bonding between organic chemicals and perovskite layers. Here we reported a facile inorganic layer passivating method containing strong Pb–S bonding by using ammonium sulfide treatment. A compact PbS_x layer was in-situ formed on the top surface of the perovskite film, which could passivate and protect the perovskite surface to enhance the performance and stability. Our novel inorganic passivation layer strategy demonstrates great potential for the development of high efficiency hybrid and robust perovskite optoelectronics.
文摘The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are identified as crucial solutions. Organic perovskites MAPbI<sub>3</sub> and FAPbI<sub>3</sub>, characterized by their abundance, low cost, and ease of synthesis, are emerging as candidates for study to enhance their competitiveness. It is within this framework that this article presents a comparative analysis of the performances of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites in the context of photovoltaic devices. The analysis focuses on the optoelectronic characteristics and stability of these high-potential materials. The optical properties of perovskites are rigorously evaluated, including band gaps, photoluminescence, and light absorption, using UV-Vis spectroscopy and photoluminescence techniques. The crystal structure is characterized by X-ray diffraction, while film morphology is examined through scanning electron microscopy. The results reveal significant variations between the two types of perovskites, directly impacting the performance of resulting solar devices. Simultaneously, the stability of perovskites is subjected to a thorough study, exposing the materials to various environmental conditions, highlighting key determinants of their durability. Films of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> demonstrate distinct differences in terms of topography, optical performance, and stability. Research has unveiled that planar perovskite solar cells based on FAPbI<sub>3</sub> offer higher photoelectric conversion efficiency, surpassing their MAPbI<sub>3</sub>-based counterparts in terms of performance. These advancements aim to overcome stability constraints and enhance the long-term durability of perovskites, ultimately aiming for practical application of these materials. This comprehensive comparative analysis provides an enlightened understanding of the optoelectronic performance and stability of MAPbI<sub>3</sub> and FAPbI<sub>3</sub> perovskites, which is critically important to guide future research and development of solar devices that are both more efficient and sustainable.
基金supported by the Natural Science Foundation of Inner Mongolia of China[grant number 2021BS02018 and 2023QN02008].
文摘Iron oxide-based heterojunctions have garnered widespread interest in the field of photocatalysis due to their outstanding photoelectric properties.However,there remains a lack of an in-depth understanding of the relationship between the interfacial structure and electronic properties of these heterojunctions at the atomic scale.Access to such knowledge is critical for guiding the design and enhancing the efficiency of novel photocatalyst classes.Herein,a first-principles computational investigation focuses on the interfacial geometry,electronic structure and electron transfer mechanisms of MAPbI3/α-Fe_(2)O_(3),MAPbI3/γ-Fe_(2)O_(3) and MAPbI3/TiO_(2) heterojunctions.Compared to the classical MAPbI3/TiO_(2) system,the influence of iron coordination at the two octahedral iron sites ofα-Fe_(2)O_(3) and at both tetrahedral and octahedral iron sites ofγ-Fe_(2)O_(3) is investigated.This indicates that the stability of the interface on theγ-Fe_(2)O_(3)(111)surface is enhanced by the octahedrally coordinated iron,whereas the subsurface Fe_(o2) plays a pivotal role in stabilizing the interface with PbI on theα-Fe_(2)O_(3)-Fe_(o1) surface.Furthermore,a notable modulation by different iron coordinations of the valence band maximum charge distribution at theα-Fe_(2)O_(3)/PbI andγ-Fe_(2)O_(3)/PbI interfaces is observed,which is pivotal for the separation and transfer of photogenerated electrons and holes.Combined with the comprehensive analysis of the band structure,electrostatic potential and average plane charge density of the heterojunction,the MAPbI3/iron oxide heterojunction is consistent with the S-scheme heterojunction mechanism.Molecular adsorption simulations of CO_(2),O_(2) and H_(2)O show that theα-Fe_(2)O_(3)-Fe_(o1)/PbI interface stands out with the lowest adsorption energy,indicating its superior photocatalytic potential for CO_(2) reduction and dye degradation.These findings provide valuable insights into the design principles of photocatalytic materials,emphasizing the strategic manipulation of iron coordination to optimize iron-based heterojunction performance.
基金supported by King Saud University,Riyadh,Saudi Arabia,under project number RSP2024R397CONAHCYT for the scholarship awarded.
文摘Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a significant increase in grain size to 29.64 nm,alongside reductions in dislocation line density to 5.39×1014 m−2 and d-spacing to 3.18Å,while maintaining the native cubic crystal structure of MAPbI2Br.This research demonstrates a reduction in deep-level trap states with Ag doping,along with a significant narrowing of the band gap to 1.91 eV in the 6%Ag-doped MAPbI2Br.Moreover,the refractive index and extinction coefficient increased to 2.54 and 2.13,respectively.Regarding solar cell performance,all cells demonstrated encouraging outcomes;still,the 6%Ag-doped cell distinguished itself with a fill factor of 0.82,an open-circuit voltage of 1.07 V,an outstanding short-circuit current density of 11.31 mA/cm²,and an efficiency of 10.03%.These results highlight the effectiveness of Ag doping in improving perovskite solar cell technology,marking a notable progress in this field.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12175131 and 11905133)the China Postdoctoral Science Foundation(Grant No.2021M692021)。
文摘Time-of-flight(ToF)transient current method is an important technique to study the transport characteristics of semiconductors.Here,both the direct current(DC)and pulsed bias ToF transient current method are employed to investigate the transport properties and electric field distribution inside the MAPbI_(3) single crystal detector.Owing to the almost homogeneous electric field built inside the detector during pulsed bias ToF measurement,the free hole mobility can be directly calculated to be about 22 cm^(2)·V^(-1)·s^(-1),and the hole lifetime is around 6.5μs–17.5μs.Hence,the mobility-lifetime product can be derived to be 1.4×10^(-4)cm^(2)·V^(-1)–3.9×10^(-4)cm^(2)·V^(-1).The transit time measured under the DC bias deviates with increasing voltage compared with that under the pulsed bias,which arises mainly from the inhomogeneous electric field distribution inside the perovskite.The positive space charge density can then be deduced to increase from 3.1×10^(10)cm^(-3)to 6.89×10^(10)cm^(-3)in a bias range of 50 V–150 V.The ToF measurement can provide us with a facile way to accurately measure the transport properties of the perovskite single crystals,and is also helpful in obtaining a rough picture of the internal electric field distribution.
基金financial support of the National Natural Science Foundation of China(No.21903023)Science and Technology Innovation Program of Hunan Province(No.2021RC3089)+2 种基金China Postdoctoral Science Foundation(2021M701168)the UNSW Materials and Manufacturing Futures Institutefinancial support of the U.S.Department of Energy(DE-SC0014429).
文摘The ability of methylammonium lead triiodide(MAPbI3)to achieve photoelectric conversion efficiency that is on par with crystalline silicon has led to a surge of interest in perovskite photovoltaics.However,an in-depth understanding of how the ubiquitous coupling between the fast rovibrational movements of the organic cations and the phonon vibrations of the inorganic framework affects the relaxation and recombination of hot carriers remains largely elusive.Access to such knowledge is critical to guide design and increase efficiency of new classes of perovskite solar cells.We report a time-domain ab initio investigation of temperature dependent excited state dynamics in MAPbI3,with particular emphasis on nuclear anharmonic effects.The observed strong anharmonicity is attributed to softness of the material and unusual dynamical coupling between the organic and inorganic components.At an elevated temperature,the hydrogen bonding between MA and iodines is weakened,enhancing rotation of MA cations,which become more dynamically disordered.As a result,thermal vibrations of the inorganic Pb-Ⅰ sublattice are suppressed,and the lattice anharmonicity is decreased.Thermal fluctuations of the electronic energy levels are found to follow the trend of anharmonic motions of Pb and I atoms,with holes relaxing faster to the band edges than electrons,due to higher density of the hole states.While elevated temperature accelerates intraband carrier cooling,it slows nonradiative carrier recombination.The latter result is important for performance,since solar cells and other devices heat up during operation.The reported signatures of coupled structural dynamics of the organic cations and inorganic framework unravel the interplay between anomalous structural fluctuations and charge carrier dynamics,which is of particular importance for fundamental understanding of the structure-property relationships in hybrid metal halide perovskites.
基金the National Natural Science Foundation of China(No.22373033)the Science and Technology Innovation Program of Hunan Province(No.2021RC3089)+3 种基金the National Natural Science Foundation of China(Grant No.22373082)the Science and Technology Innovation Program of Hunan Province(2023RC1055)the Innovation and Entrepreneurship Training Program for Undergraduates(No.D202305231555195730)O.V.P.acknowledges support of the US Department of Energy(grant DE-SC0014429).
文摘Hybrid organic–inorganic perovskites are promising for optoelectronic applications,yet the impact of intrinsic defects on hot carrier dynamics remains poorly understood.Here,we investigate hot carrier dynamics in methylammonium lead triiodide(MAPbI_(3))perovskite containing Pb vacancies,a prevalent defect type,using ab initio nonadiabatic molecular dynamics.We observe pronounced slower hot carrier cooling in Pb vacancy-containing MAPbI_(3)compared to pristine system.In particular,the hot hole cooling in the Pb vacancy system is approximately an order of magnitude slower than that of pristine perovskite for states situated∼0.5 eV below the top of the valence bands.This deceleration arises primarily from reduced nonadiabatic couplings due to charge state localization and suppressed fluctuations of the inorganic sub-lattice,facilitated by the enhanced rotational disorder of MA cations in the presence of Pb vacancies.Additionally,Pb vacancies introduce intraband defect states capable of trapping photogenerated hot holes,further delaying the hot carrier cooling process.The absence of trap-assisted hot carrier cooling dynamics in hybrid perovskite is consistent with the well-established consensus of defect tolerance in these materials.Our findings provide crucial insights into defect-mediated hot carrier dynamics in hybrid perovskites,holding significant implications for advancing the development of perovskite solar cells and related devices through defect engineering.
文摘Using the spray pyrolysis process,the work shows the production of pristine and 6%Ag-doped methylammonium lead iodide bromide(MAPbI2Br)film.Through X-ray diffraction analysis,it was found that Ag doping led to a significant increase in grain size to 29.64 nm,alongside reductions in dislocation line density to 5.39×1014 m−2 and d-spacing to 3.18Å,while maintaining the native cubic crystal structure of MAPbI2Br.This research demonstrates a reduction in deep-level trap states with Ag doping,along with a significant narrowing of the band gap to 1.91 eV in the 6%Ag-doped MAPbI2Br.Moreover,the refractive index and extinction coefficient increased to 2.54 and 2.13,respectively.Regarding solar cell performance,all cells demonstrated encouraging outcomes;still,the 6%Ag-doped cell distinguished itself with a fill factor of 0.82,an open-circuit voltage of 1.07 V,an outstanding short-circuit current density of 11.31 mA/cm²,and an efficiency of 10.03%.These results highlight the effectiveness of Ag doping in improving perovskite solar cell technology,marking a notable progress in this field.
基金supported by National Key Research and Development Program of China(2022YFA1604403)National Natural Science Foundation of China(12274157,12021004,12274334,11904271)Natural Science Foundation of Hubei Province(2023AFA076).
文摘The strong coupling between photons and phonons in polar materials gives rise to phonon-polaritons that encapsulate a wealth of physical information,offering crucial tools for the ultrafast terahertz sources and the topological engineering of terahertz light.However,it is still quite challenging to form and manipulate the terahertz phonon-polaritons under the ultrastrong coupling regime till now.In this work,we demonstrate the ultrastrong coupling between the phonon(at 0.95 THz)in a MAPbI3 film and the metallic bound states in the continuum(BICs)in Au metasurfaces.The Rabi splitting can be continuously tuned from 28%to 48.4%of the phonon frequency by adjusting the parameters(size,shape and period)of Au metasurfaces,reaching the ultrastrong coupling regime.By introducing wavelet transform,the mode evolution information of the terahertz phonon-polariton is successfully extracted.It indicates that the phonon radiation intensity of the MAPbI_(3)film is enhanced as the coupling strength is increased.This work not only establishes a new platform for terahertz devices but also opens new avenues for exploring the intricate dynamics of terahertz phonon-polaritons.
基金financial support from the National Natural Science Foundation of China(No.52103223)the Natural Science Basic Research Program of Shaanxi(No.2023-JC-YB-413)+2 种基金the Natural Science Foundation of Heilongjiang Province of China(No.YQ2023E027)the Key Laboratory of Functional Molecular Solids,Ministry of Education(No.FMS20230010)the Fundamental Research Funds for the Central Universities(Nos.3072024GH2605,3072024XX2613,and 3072024XX2616).
文摘Organic–inorganic hybrid perovskites are quite promising candidates in the field of electromagnetic wave (EMW) absorption due to their unique physicochemical properties. However, it is still a considerable challenge to satisfy the light weight, broad bandwidth, and strong absorption properties simultaneously. Herein, the solution of methylammonium lead iodide (MAPbI3) perovskites was infiltrated into the pores of reduced graphene oxide (rGO) aerogels. After drying, a series of MAPbI3/rGO composite aerogel (MGA) materials were synthesized by anchoring the MAPbI3 perovskite nanoparticles to rGO sheets with the assistance of rGO templates. Through the adjustment of component ratios, excellent EMW absorption properties are obtained with the synergistic effects of polarization loss, conduction loss, and multiple reflection and scattering of MAPbI3 and rGO. The porous structure of the aerogel and the suitable group distribution ratio allowed the MGA-4 samples to obtain excellent impedance matching and ultra-low density of ∼ 7.69 mg·cm−3. At a low filling ratio of 15 wt.%, the MGA-4 sample simultaneously achieves highly efficient and broadband EMW absorption performance at a thin thickness. The MGA-4 sample obtained a minimum reflection loss value of −64.35 dB and the effective absorption bandwidth (EAB) value of 5.4 GHz at a thickness of 2.08 mm and a maximum EAB (EABmax) value of 6.2 GHz under 2.22 mm. The MGA-5 sample obtained a maximum EAB value of 6.4 GHz with the thinckness of 2.16 mm. Furthermore, the simulation results of the radar cross-section (RCS) verified the component-optimized composites are capable of achieving excellent EMW attenuation. This paper provides a new approach and valuable reference for the development of hybrid perovskite-based microwave absorption materials with lightweight, ultra-broadband, and strong absorption properties.
