Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

Light-emitting diodes based on all-inorganic copper halide perovskite with self-trapped excitons

Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.

Indium-doped perovskite-related cesium copper halide scintillator films for high-performance X-ray imaging

Scintillators are widely utilized in high-energy radiation detection in view of their high light yield and short fluorescence decay time.However,constrained by their current shortcomings,such as complex fabrication procedures,high temperature,and difficulty in the large scale,it is difficult to meet the increasing demand for costeffective,flexible,and environment-friendly X-ray detection using traditional scintillators.Perovskite-related cesium copper halide scintillators have recently received multitudinous research due to their tunable emission wavelength,high photoluminescence quantum yield(PLQY),and excellent optical properties.Herein,we demonstrated a facile solution-synthesis route for indium-doped all-inorganic cesium copper iodide(Cs_(3)Cu_(2)I_(5))powders and a high scintillation yield flexible film utilizing indium-doped Cs_(3)Cu_(2)I_(5)powders.The large area flexible films achieved a PLQY as high as 90.2%by appropriately adjusting the indium doping concentration,much higher than the undoped one(73.9%).Moreover,benefiting from low self-absorption and high PLQY,the Cs_(3)Cu_(2)I_(5):In films exhibited ultralow detection limit of 56.2 n Gy/s,high spatial resolution up to 11.3 lp/mm,and marvelous relative light output with strong stability,facilitating that Cs_(3)Cu_(2)I_(5):In films are excellent candidates for X-ray medical radiography.Our work provides an effective strategy for developing environment-friendly,low-cost,and efficient scintillator films,showing great potential in the application of highperformance X-ray imaging.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

具有高效发光性能的亚铜卤化物纳米团簇应用于X-射线闪烁体

闪烁体可以将高能辐射转化为可见光,作为一种光电功能材料已经广泛应用于各种放射探测领域.虽然三维Pb基钙钛矿纳米晶可以开发为X射线闪烁体材料,但是其较低的光产额和铅毒性问题在一定程度上限制了其应用.为解决这一问题,本文重点关注零维金属卤化物发光材料,合成了一系列基于孤立[Cu_(4)X_(6)]^(2−)纳米团簇的零维卤化物,并将其开发应用为闪烁体发光材料.在紫外线或蓝光激发下,该卤化物纳米团簇均显示出宽带光发射,发光颜色可覆盖绿色、橙色到红色,并且具有近乎100%的光量子产率和较大的Stokes位移(>1.3 eV).特别突出的是,该类卤化物纳米团簇由于较高的发光量子产率、较小的光学自吸收和较强的X射线衰减效率,表现出优异的X-射线闪烁发光性能,光产额最高可达到24,240 photons MeV−1.材料的闪烁发光强度与X射线剂量呈现线性关系,检测范围较宽,且检测极限(0.7563μGy_(air)s^(−1))远低于常规医学诊断所要求的计量(5.5μGy_(air)s^(−1)).X-射线成像结果表明该纳米团簇余晖衰减时间较短(1.3 ms),空间分辨率较高(14.83 lp mm^(−1)),在医学成像等领域具有潜在的应用价值.该项工作表明,亚铜卤化物纳米团簇具有高效、稳定、无毒、发光效率高等优点,有望成为一种优异的新型闪烁体发光材料.

X-ray scintillation in lead-free double perovskite crystals

Metal halide perovskites have shown great performance for various applications,including solar cells,light emitting diodes,and radiation detectors,but they still suffer from the toxicity of lead and instability.Here we report the use of lanthanide series as trivalent metals to obtain low toxicity and highly stable double perovskites(Cs_2NaLnCl_6,Ln=Tb or Eu)with high scintillation light yield.The crystals exhibit typical f-f transitions of lanthanide cations,while Cs_2NaTbCl_6exhibits strong green photoluminescence,and Cs_2NaEuCl_6exhibits red photoluminescence.Under X-ray radiations,the light yield of Cs_2NaTbCl_6reaches46600 photons MeV^(-1),much higher than that of the commercially used(Lu,Y)_2SiO_5:Ce^(3+)crystals(LYSO,28500 photons MeV^(-1)),and previously reported lead-based perovskites(14000 photons MeV^(-1)).As a new member of lead-free perovskites,lanthanide-based double perovskites open up a new route toward radiation detections and potential medical imaging.

用于高性能X射线探测的无铅卤化物钙钛矿Cs_(3)Bi_(2)Br_(9)单晶

近年来,全无机无铅卤化物钙钛矿以其良好的环境稳定性和热稳定性、优异的光电性能以及环境友好性而受到广泛关注.本文采用改进的垂直布里奇曼法首次生长出直径12 mm、长度约40 mm、透明性良好的Cs_(3)Bi_(2)Br_(9)单晶.生长的Cs_(3)Bi_(2)Br_(9)单晶的电阻率约为6.8×10^(11)Ωcm,透过率约为80%.在(−120)晶面内,载流子迁移率为0.17 cm^(2)V^(−1)s^(−1),缺陷态密度为9.7×10^(10)cm^(−3).在X射线探测方面,Cs_(3)Bi_(2)Br_(9)单晶最大灵敏度约为230.4μC Gyair−1 cm^(−2);暗电流密度约为17.8 pA mm^(−2),且没有漂移现象,这表明Cs_(3)Bi_(2)Br_(9)单晶具有更小的暗电流噪声,有利于获得更低的检测限.

Organic–inorganic hybrid perovskite scintillators for mixed field radiation detection

Sensitive and fast detection of neutrons and gamma rays is vital for homeland security,high-energy physics,and proton therapy.Fast-neutron detectors rely on light organic scintillators,andγ-ray detectors use heavy inorganic scintillators and semiconductors.Efficient mixed-field detection using a single material is highly challenging due to their contradictory requirements.Here we report hybrid perovskites(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed-field radiation detection.High neutron absorption due to a high density of hydrogen,strong radiative recombination within the highly confined[PbX_(6)]^(4-)layer,and sub-nanometer distance between absorption sites and radiative centers,enable a light yield of 41000 photons/MeV,detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons andγ-rays,outperforming commonly used fast-neutron scintillators.Neutron energy spectrum,time-of-flight based fast-neutron/γ-ray discrimination and neutron yield monitoring were all successfully achieved using(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)detectors.We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction.We envision that molecular hybridized scintillators open a new avenue for mixed-field radiation detection and imaging.

Antimony doped Cs2SnCl6 with bright and stable emission

Lead halide perovskites,with high photoluminescence efficiency and narrow・band emission,are promising materials for display and lighting.However,the lead toxicity and environmental sensitivity hinder their potential applications.Herein,a new antimony・doped lead-free inorganic perovskites variant Cs2SnCl6:xSb is designed and synthesized.The perovskite variant Cs2SnCl6:xSb exhibits a broadband orange-red emission,with a photoluminescence quantum yield(PLQY)of 37%.The photoluminescence of Cs2SnCl6:xSb is caused by the ionoluminescence of Sb3+within Cs2SnCl6 matrix,which is verified by temperature dependent photoluminescence(PL)and PL decay measurements.In addition,the all inorganic structure renders Cs2SnCl6:xSb with excellent thermal and water stability.Finally,a white light-emitting diode(white-LED)is fabricated by assembling Cs2SnCl6:0.59%Sb,Cs2SnCl6:2.75%Bi and Ba2Sr2SiO4:Eu2+onto the commercial UV LED chips,and the color rendering index(CRI)reaches 81.

通过链状二胺构建强各向异性三碘化合物DMEDA·I6（英文）

线性链状三碘化物的研究重点主要体现在两个方面:减小碘离子之间距离,有利于电子转移;提高碘离子排列线性度,可以实现强各向异性.本文采用了一种新策略,使用链状二胺(N,N'-二甲基乙二胺,DMEDA)阳离子与三碘化物离子配位,形成一维线性三碘化物DMEDA·I6.相较于之前报道的三碘化物,该三碘化物相邻I3^-离子之间的距离最短,具有较好的线性度;同时具有1.36 e V的电子带隙,具有半导体性能.理论模拟和实验表征都表明该化合物具有强的各向异性.模拟预测沿a轴和垂直于a轴的吸收差异以及电子和空穴有效质量的差异最多可达100倍.我们还基于DMEDA·I6构造了一个光电导探测器,并获得了低暗电流和各向异性的光响应.DMEDA·I6的强各向异性和半导体特性使其成为偏振探测相关应用的有利竞争者.

Vertical matrix perovskite X-ray detector for effective multi-energy discrimination

Multi-energy X-ray detection is sought after for a wide range of applications including medical imaging,security checking and industrial flaw inspection.Perovskite X-ray detectors are superior in terms of high sensitivity and low detection limit,which lays a foundation for multi-energy discrimination.However,the extended capability of the perovskite detector for multi-energy X-ray detection is challenging and has never been reported.Herein we report the design of vertical matrix perovskite X-ray detectors for multi-energy detection,based on the attenuation behavior of X-ray within the detector and machine learning algorithm.This platform is independent of the complex X-ray source components that constrain the energy discrimination capability.We show that the incident X-ray spectra could be accurately reconstructed from the conversion matrix and measured photocurrent response.Moreover,the detector could produce a set of images containing the density-graded information under single exposure,and locate the concealed position for all low-,medium-and high-density substances.Our findings suggest a new generation of X-ray detectors with features of multi-energy discrimination,density differentiation,and contrast-enhanced imaging.

Inorganic antimony halide hybrids with broad yellow emissions

Lead halide perovskites exhibit unexceptionable photoelectric properties.However,these materials are unsatisfactory in terms of stability and toxicity.Herein,we report Rb7 Sb3 Cl16 as a new kind of lead free perovskite variants.This material can be easily obtained through hydrothermal reactions.The composition is determined through structure refinement,elemental analysis and X-ray photoelectron spectra.Rb7 Sb3 Cl16 exhibits a broad yellow emission at 560 nm,with a Stokes shift of 175 nm and a photoluminescence quantum yield(PLQY)around 26%.Rb7 Sb3 Cl16 also shows good thermal and water stability due to its inorganic composition.White light-emitting diodes(LEDs)are constructed by combining Rb7 Sb3 Cl16 as yellow phosphors,our previously reported Cs2 SnCl6:2.75%Bi as blue phosphors,and commercial UV LED chips as the excitation source,producing a white light with the Commission Internationale de’Eclairage(CIE)color coordinates at(0.39,0.38).

Sb_(2)Se_(3) film with grain size over 10μm toward X-ray detection

Direct X-ray detectors are considered as competitive next-generation X-ray detectors because of their high spatial resolution,high sensitivity,and simple device configuration.However,their potential is largely limited by the imperfections of traditional materials,such as the low crystallization temperature of α-Se and the low atomic numbers of α-Si and α-Se.Here,we report the Sb_(2)Se_(3) X-ray thin-film detector with a p-n junction structure,which exhibited a sensitivity of 106.3 μC/(Gyair·cm^(2))and response time of<2.5 ms.This decent performance and the various advantages of Sb_(2)Se_(3),such as the average atomic number of 40.8 and μτ product(μ is the mobility,and τ is the carrier lifetime)of 1.29×1O^(-5) cm^(2)/V,indicate its potential for application in X-ray detection.

Dark current modeling of thick perovskite X‑ray detectors

Metal halide perovskites(MHPs)have demonstrated excellent performances in detection of X-rays and gamma-rays.Most studies focus on improving the sensitivity of single-pixel MHP detectors.However,little work pays attention to the dark current,which is crucial for the back-end circuit integration.Herein,the requirement of dark current is quantitatively evaluated as low as 10^(−9)A/cm^(2)for X-ray imagers integrated on pixel circuits.Moreover,through the semiconductor device analysis and simulation,we reveal that the main current compositions of thick perovskite X-ray detectors are the thermionic-emission current(J_(T))and the generation-recombination current(J_(g-r)).The typical observed failures of p-n junctions in thick detectors are caused by the high generation-recombination current due to the band mismatch and interface defects.This work provides a deep insight into the design of high sensitivity and low dark current perovskite X-ray detectors.

Oxide perovskite Ba_(2)AgIO_(6)wafers for X-ray detection

X-ray detection is of great significance in biomedical,nondestructive,and scientific research.Lead halide perovskites have recently emerged as one of the most promising materials for direct X-ray detection.However,the lead toxicity remains a worrisome concern for further commercial application.Great efforts have been made to search for lead-free perovskites with similar optoelectronic properties.Here,we present a lead-free oxide double perovskite material Ba2AgIO6 for X-ray detection.The lead-free,all-inorganic nature,as well as the high density of Ba2AgIO6,promises excellent prospects in X-ray applications.By employing the hydrothermal method,we successfully synthesized highly crystalline Ba2AgIO6 powder with pure phase.Furthermore,we prepared Ba2AgIO6 wafers through isostatic pressure and built X-ray detectors with Au/Ba2AgIO6 wafer/Au photoconductive structure.The as-prepared X-ray detectors showed a sensitivity of 18.9μC/(Gyair$cm2)at 5 V/mm,similar to commercialα-Se detectors showcasing their advantages for X-ray detection.

Template directed perovskite X-ray detectors towards low ionic migration and low interpixel cross talking

The metal halide perovskites exhibit excellent performance as the direct X-ray detectors owing to their strong absorption capability,long carrier lifetime and diffusion length,radiation ruggedness,etc.For imaging applications,the ionic migration of perovskites and charge sharing effect between the adjacent pixels have a significantly negative impact on the spatial resolution.Herein,for the first time,the porous anodic aluminum oxides(AAO)have been used as a template to grow the CsPbBr2I thick film for the direct X-ray detection.Benefiting from the oxygen passivation effect,the activation energy for ionic migration has been observed to increase to 0.701 eV,whereas the dark current drift(1.01×10^(-5)nA cm^(-1)s^(-1)V^(-1))is one to two orders of magnitude lower than the other lead halide perovskite single crystals and films.Moreover,the AAO insulating wall effectively blocks the charge diffusion effect across a pixel pitch of 10^m.Overall,the findings reported in this study open a new route for reducing the ionic migration and pixel crosstalk,thus,bringing the perovskite X-ray detectors close to the practical applications.