Hybrid perovskite solar cell(PSC)has attracted extensive research interest due to its rapid increase in efficiency,regarding as one of the most promising candidates for the next-generation photovoltaic technology.The ...Hybrid perovskite solar cell(PSC)has attracted extensive research interest due to its rapid increase in efficiency,regarding as one of the most promising candidates for the next-generation photovoltaic technology.The certified power conversion efficiency of the devices based on formamidinium lead iodide(FAPbI_(3))perovskite has reached 25.5%,approaching the record of monocrystalline silicon solar cells.Unfortunately,the blackα-phase FAPbI_(3)materials can spontaneously transform to non-optically activeδ-phase at room temperature,which greatly hinder their photovoltaic application.In order to overcome this problem,various strategies,especially introducing methylammonium(MA^(+)),caesium(Cs^(+))and bromide(Br^(-))ions into the materials,have been widely adopted.However,MA^(+)can largely reduce the thermal stability of the materials.Furthermore,the introduction of Br^(-)can enlarge the materials'bandgap,resulting in a reduced theoretical efficiency.Keeping these in mind,developing the strategies which without using MA^(+)and Br^(-)is the inevitable trend.Here,we focus on the recent progresses of stabilizingαFAPbI_(3)without employing MA^(+)and Br^(-),and discuss the advantages of inorganic ions doping and dimensionality engineering to stabilizedαFAPbI_(3).Meanwhile,in order to deeply understand the relationship between the semiconducting properties and device performance of the corresponding materials,we then summarize several significant strategies to suppress the non-radiation recombination,such as interface modification and trap passivation.Finally,we propose to develop more effective'A-site'alternatives to stabilizeαFAPbI_(3),which is expected to achieve high-efficient PSCs with long-term stability,facilitating its commercialization process.展开更多
The dielectric confinement effect plays an essential role in optoelectronic devices.Existing studies on the relationship between the dielectric confinement and the photoelectric properties are inadequate.Herein,three ...The dielectric confinement effect plays an essential role in optoelectronic devices.Existing studies on the relationship between the dielectric confinement and the photoelectric properties are inadequate.Herein,three organic spacers with different dielectric constants are employed to tune the exciton dynamics of quasi-two-dimensional(quasi-2D)Ruddlesden–Popper perovskite films.Femtosecond transient absorption spectroscopy reveals that the small dielectric constant ligand enables a weak dynamic disorder and a large modulation depth of the coherent phonons,resulting in a more complete energy transfer and the inhibition of a trap-mediated nonradiative recombination.Additionally,the increase in the bulk-ligand dielectric constant reduces the corresponding exciton binding energy and then suppresses the Auger recombination,which is beneficial for high-luminance lightemitting diodes.This work emphasizes the importance of dielectric confinement for regulating the exciton dynamics of layered perovskites.展开更多
Organic-inorganic layered perovskites are two-dimensional quantum well layers in which the layers of lead halide octahedra are stacked between the organic cation layers.The packing geometry of the soft organic molecul...Organic-inorganic layered perovskites are two-dimensional quantum well layers in which the layers of lead halide octahedra are stacked between the organic cation layers.The packing geometry of the soft organic molecules and the stiff ionic crystals induce structural deformation of the inorganic octahedra,generating complex lattice dynamics.Especially,the dielectric confinement and ionic sublattice lead to strong coupling between the photogenerated excitons and the phonons from the polar lattice which intensively affects the properties for device applications.The anharmonicity and dynamic disorder from the organic cations participate in the relaxation dynamics coupled with excitations.However,a detailed understanding of this underlying mechanism remains obscure.This work investigates the electron–optical phonon coupling dynamics by employing ultrafast pump-probe transient absorption spectroscopy.The activated different optical phonon modes are observed via systematic studies of(PEA)_(2)PbBr_(4) perovskite films on the ultrafast lattice vibrational dynamics.The experimental results indicate that solvent engineering has a significant influence on lattice vibrational modes and coherent phonon dynamics.This work provides fresh insights into electron-optical phonon coupling for emergent optoelectronics development based on layered perovskites.展开更多
Metal-halide perovskite light-emitting diodes(PeLEDs)possess wide colour gamut,high luminescence efficiency,and low-cost synthesis,making them a promising photonic source for next-generation display applications.Since...Metal-halide perovskite light-emitting diodes(PeLEDs)possess wide colour gamut,high luminescence efficiency,and low-cost synthesis,making them a promising photonic source for next-generation display applications.Since the first room-temperature emission PeLED was demonstrated in 2014,their performance has improved rapidly within a few years,leading to considerable attention from academia and industry.In this review,we discuss the primary technical bottlenecks of PeLEDs for commercial display applications,including large-area PeLED preparation,patterning strategies,and flexible PeLED devices.We review the technical approaches for achieving these targets and highlight the current challenges while providing an outlook for these perovskite materials and PeLED devices to meet the requirements of the next-generation high-colour-purity full-colour display market.展开更多
Quasi-two-dimensional(quasi-2D)perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation lightemitti...Quasi-two-dimensional(quasi-2D)perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation lightemitting diodes(LEDs).The outstanding optical properties originate from their structural characteristics.In particular,the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectricand quantum-confinement effects;the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields(PLQYs),particularly at low excitation intensities.The review herein presents an overview of the inherent properties of quasi-2D perovskite materials,the corresponding energy transfer and spectral tunability methodologies for thin films,as well as their application in high-performance LEDs.We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs.The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.展开更多
Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lea...Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lead based perovskites. However, the performance of lead-based perovskites solar cells is still far inferior to their lead analogues owing to the unavoidable oxidation of Sn^(2+)to Sn^(4+). Here we introduced two-dimensional(2D) perovskite on the top of three dimensional(3D) perovskite film as a capping layer to reduce the self-oxidation, and thus improved the device stability. 2D capping layer was then confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analysis. The existence of the 2D protecting thin layer significantly reduce the spontaneous Sn^(2+)oxidation, thus improve the device performance and reduce the hysteresis. The phenomena could be ascribed to the improved charge extraction efficiency causing by prohibited nonradiative recombination. On top of this, the photovoltaic devices based on conventional-structure configuration were fabricated. Taking advantage of the 2D capping layer, 2D/3D hybrid perovskite photovoltaic devices achieve a open-circuit voltage(Voc) of 0.77 V with short circuit current density(Jsc) of 26.60 mA cm^(-2), delivering the best-performing power conversion efficiency of 15.5%. Moreover, the 2D/3D perovskite devices maintained 60% its initial efficiency after 40 h exposed in air(humidity around 30%, temperature 22 °C),while 3D perovskite-based devices completely failed.展开更多
基金financial support from the National Natural Science Foundation of China(No.21771114,91956130)financial support from Distinguished Young Scholars of Tianjin(No.19JCJQJC62000)。
文摘Hybrid perovskite solar cell(PSC)has attracted extensive research interest due to its rapid increase in efficiency,regarding as one of the most promising candidates for the next-generation photovoltaic technology.The certified power conversion efficiency of the devices based on formamidinium lead iodide(FAPbI_(3))perovskite has reached 25.5%,approaching the record of monocrystalline silicon solar cells.Unfortunately,the blackα-phase FAPbI_(3)materials can spontaneously transform to non-optically activeδ-phase at room temperature,which greatly hinder their photovoltaic application.In order to overcome this problem,various strategies,especially introducing methylammonium(MA^(+)),caesium(Cs^(+))and bromide(Br^(-))ions into the materials,have been widely adopted.However,MA^(+)can largely reduce the thermal stability of the materials.Furthermore,the introduction of Br^(-)can enlarge the materials'bandgap,resulting in a reduced theoretical efficiency.Keeping these in mind,developing the strategies which without using MA^(+)and Br^(-)is the inevitable trend.Here,we focus on the recent progresses of stabilizingαFAPbI_(3)without employing MA^(+)and Br^(-),and discuss the advantages of inorganic ions doping and dimensionality engineering to stabilizedαFAPbI_(3).Meanwhile,in order to deeply understand the relationship between the semiconducting properties and device performance of the corresponding materials,we then summarize several significant strategies to suppress the non-radiation recombination,such as interface modification and trap passivation.Finally,we propose to develop more effective'A-site'alternatives to stabilizeαFAPbI_(3),which is expected to achieve high-efficient PSCs with long-term stability,facilitating its commercialization process.
基金National Natural Science Foundation of China(12347158,11804084,12074104,61627818,U1804261)Natural Science Foundation of Henan Province(222300420057)Young Backbone Teacher Training Program in Higher Education of Henan Province(2019GGJS065)。
文摘The dielectric confinement effect plays an essential role in optoelectronic devices.Existing studies on the relationship between the dielectric confinement and the photoelectric properties are inadequate.Herein,three organic spacers with different dielectric constants are employed to tune the exciton dynamics of quasi-two-dimensional(quasi-2D)Ruddlesden–Popper perovskite films.Femtosecond transient absorption spectroscopy reveals that the small dielectric constant ligand enables a weak dynamic disorder and a large modulation depth of the coherent phonons,resulting in a more complete energy transfer and the inhibition of a trap-mediated nonradiative recombination.Additionally,the increase in the bulk-ligand dielectric constant reduces the corresponding exciton binding energy and then suppresses the Auger recombination,which is beneficial for high-luminance lightemitting diodes.This work emphasizes the importance of dielectric confinement for regulating the exciton dynamics of layered perovskites.
基金supported by the National Natural Science Foundation of China(Nos.U1804261,61627818,12074104,11804084,62075058,and 11827806)Natural Science Foundation of Henan Province(No.222300420057)+1 种基金the Outstanding Youth Foundation of Henan Normal University(No.20200171)the Young Backbone Teacher Training Program in Higher Education of Henan Province(No.2019GGJS065).
文摘Organic-inorganic layered perovskites are two-dimensional quantum well layers in which the layers of lead halide octahedra are stacked between the organic cation layers.The packing geometry of the soft organic molecules and the stiff ionic crystals induce structural deformation of the inorganic octahedra,generating complex lattice dynamics.Especially,the dielectric confinement and ionic sublattice lead to strong coupling between the photogenerated excitons and the phonons from the polar lattice which intensively affects the properties for device applications.The anharmonicity and dynamic disorder from the organic cations participate in the relaxation dynamics coupled with excitations.However,a detailed understanding of this underlying mechanism remains obscure.This work investigates the electron–optical phonon coupling dynamics by employing ultrafast pump-probe transient absorption spectroscopy.The activated different optical phonon modes are observed via systematic studies of(PEA)_(2)PbBr_(4) perovskite films on the ultrafast lattice vibrational dynamics.The experimental results indicate that solvent engineering has a significant influence on lattice vibrational modes and coherent phonon dynamics.This work provides fresh insights into electron-optical phonon coupling for emergent optoelectronics development based on layered perovskites.
基金support from the National Key Research and Development Program of China(2022YFE0201500)support from the National Science Fund for Distinguished Young Scholars(No.T2225024)support from the National Natural Science Foundation of China(Nos.91956130,62104116).
文摘Metal-halide perovskite light-emitting diodes(PeLEDs)possess wide colour gamut,high luminescence efficiency,and low-cost synthesis,making them a promising photonic source for next-generation display applications.Since the first room-temperature emission PeLED was demonstrated in 2014,their performance has improved rapidly within a few years,leading to considerable attention from academia and industry.In this review,we discuss the primary technical bottlenecks of PeLEDs for commercial display applications,including large-area PeLED preparation,patterning strategies,and flexible PeLED devices.We review the technical approaches for achieving these targets and highlight the current challenges while providing an outlook for these perovskite materials and PeLED devices to meet the requirements of the next-generation high-colour-purity full-colour display market.
基金the National Natural Science Foundation of China(Nos.21771114,91956130)the Natural Science Foundation of Tianjin(18YFZCGX00580).M.Yuan acknowledges financial support from Distinguished Young Scholars of Tianjin(No.19JGQJC62000).
文摘Quasi-two-dimensional(quasi-2D)perovskites have attracted extraordinary attention due to their superior semiconducting properties and have emerged as one of the most promising materials for next-generation lightemitting diodes(LEDs).The outstanding optical properties originate from their structural characteristics.In particular,the inherent quantum-well structure endows them with a large exciton binding energy due to the strong dielectricand quantum-confinement effects;the corresponding energy transfer among different n-value species thus results in high photoluminescence quantum yields(PLQYs),particularly at low excitation intensities.The review herein presents an overview of the inherent properties of quasi-2D perovskite materials,the corresponding energy transfer and spectral tunability methodologies for thin films,as well as their application in high-performance LEDs.We then summarize the challenges and potential research directions towards developing high-performance and stable quasi-2D PeLEDs.The review thus provides a systematic and timely summary for the community to deepen the understanding of quasi-2D perovskite materials and resulting LED devices.
基金supported by the National Natural Science Foundation of China(21771114)MOE 111(B12015)+2 种基金the Natural Science Foundation of Tianjin(17JCYBJC40900,18YFZCGX00580)the Fundamental Research Funds for the Central Universitiesthe financial support from "Thousand Youth Talents Plan of China"
文摘Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lead based perovskites. However, the performance of lead-based perovskites solar cells is still far inferior to their lead analogues owing to the unavoidable oxidation of Sn^(2+)to Sn^(4+). Here we introduced two-dimensional(2D) perovskite on the top of three dimensional(3D) perovskite film as a capping layer to reduce the self-oxidation, and thus improved the device stability. 2D capping layer was then confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analysis. The existence of the 2D protecting thin layer significantly reduce the spontaneous Sn^(2+)oxidation, thus improve the device performance and reduce the hysteresis. The phenomena could be ascribed to the improved charge extraction efficiency causing by prohibited nonradiative recombination. On top of this, the photovoltaic devices based on conventional-structure configuration were fabricated. Taking advantage of the 2D capping layer, 2D/3D hybrid perovskite photovoltaic devices achieve a open-circuit voltage(Voc) of 0.77 V with short circuit current density(Jsc) of 26.60 mA cm^(-2), delivering the best-performing power conversion efficiency of 15.5%. Moreover, the 2D/3D perovskite devices maintained 60% its initial efficiency after 40 h exposed in air(humidity around 30%, temperature 22 °C),while 3D perovskite-based devices completely failed.
