Low-dimensional metal halide perovskites exhibit exceptional photoelectronicproperties and intrinsic stability, positioning them as a promising class of semiconductormaterials for light-emitting devices and photodetectors. In thiswork, we present a millimeter-scale single crystal of mixed low-dimensional(one-dimensional–zero-dimensional [1D–0D]) organic lead iodide withwell-defined crystallinity. The fabricated single-crystal devices demonstratehigh-sensitivity photoresponse and x-ray detection performance. By spatiallyisolating organic molecules to form the mixed 1D–0D crystal structure, ionmigrations is effectively suppressed, resulting in a remarkable three orders ofmagnitude reduction in the dark current (56.4 pA @200 V) of the single-crystaldevices. Furthermore, by enhancing the background characteristics, weachieved an impressive low x-ray detection limit of 154.5 nGys^(-1) in the singlecrystaldevice. These findings highlight that the mixed 1D–0D organic leadiodide configuration efficiently controls ion migration within the crystal structure,offering a promising avenue for realizing high-performance perovskitebasedphotodetectors and x-ray detectors.
Low-dimensional perovskite(PVK)materials have attracted significant research interest,because of their quantum-confined effect,tunable band gap structures,and higher stability than that of three-dimensional(3D)PVKs.In semiconductor optoelectronic devices,high speed and small size are closely interlinked.The development of high-speed devices requires researchers to fully understand the properties of materials,especially the dynamic processes such as carrier recombination,separation,and transport,which often play a crucial role in the performance of devices.As an indispensable part of dynamic research,spin relaxation is also of great significance in studying the properties of materials and explore possible applications.Lead halide PVK materials have strong spin-orbit coupling(SOC),which provides a basis for information storage and processing by using spin degrees of freedom.Therefore,studying the carrier and spin dynamics of low-dimensional PVKs is an effective way to understand the internal properties of low-dimensional PVKs clearly.This paper summarizes the latest research progress on the ultrafast carrier and spin dynamics in low-dimensional PVKs,to comprehensively understand their carrier and spin behaviors and present an outlook for relevant studies in this area.
Quasi-two-dimensional(Q-2D)perovskite exhibits exceptional photoelectric properties and demonstrates reduced ion migration compared to 3D perovskite,making it a promising material for the fabrication of highly sensitive and stable X-ray detectors.However,achieving high-quality perovskite films with sufficient thickness for efficient X-ray absorption remains challenging.Herein,we present a novel approach to regulate the growth of Q-2D perovskite crystals in a mixed atmosphere comprising methylamine(CH3NH2,MA)and ammonia(NH3),resulting in the successful fabrication of high-quality films with a thickness of hundreds of micrometers.Subsequently,we build a heterojunction X-ray detector by incorporating the perovskite layer with titanium dioxide(TiO2).The precise regulation of perovskite crystal growth and the meticulous design of the device structure synergistically enhance the resistivity and carrier transport properties of the X-ray detector,resulting in an ultrahigh sensitivity(29721.4μC Gyair−1 cm−2)for low-dimensional perovskite X-ray detectors and a low detection limit of 20.9 nGyair s−1.We have further demonstrated a flat panel X-ray imager(FPXI)showing a high spatial resolution of 3.6 lpmm−1 and outstanding X-ray imaging capability under low X-ray doses.This work presents an effective methodology for achieving high-performance Q-2D perovskite FPXIs that holds great promise for various applications in imaging technology.
In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.
Xuan WangAkang ChenXinLei WuJiatao ZhangJichen DongLeining Zhang
The use of low-dimensional(LD)perovskite materials is crucial for achieving high-performance perovskite solar cells(PSCs).However,LD perovskite films fabricated by conventional approaches give rise to full coverage of the underlying 3D perovskite films,which inevitably hinders the transport of charge carriers at the interface of PSCs.Here,we designed and fabricated LD perovskite structure that forms net-like morphology on top of the underlying three-dimensional(3D)perovskite bulk film.The net-like LD perovskite not only reduced the surface defects of 3D perovskite film,but also provided channels for the vertical transport of charge carriers,effectively enhancing the interfacial charge transfer at the LD/3D hetero-interface.The net-like morphological design comprising LD perovskite effectively resolves the contradiction between interfacial defect passivation and carrier extraction across the hetero-interfaces.Furthermore,the net-like LD perovskite morphology can enhance the stability of the underlying 3D perovskite film,which is attributed to the hydrophobic nature of LD perovskite.As a result,the net-like LD perovskite film morphology assists PSCs in achieving an excellent power conversion efficiency of up to 24.6%with over 1000 h long-term operational stability.
Jinwen GuXianggang SunPok Fung ChanXinhui LuPeng ZengJue GongFaming LiMingzhen Liu
Despite their excellent intrinsic stability,low-dimensional Ruddlesden-Popper(LDRP)perovskites face challenges with low power conversion efficiency(PCE),primarily due to the widen bandgap and limited charge transport caused by the bulky spacer cation.Herein,we introduce formamidinium chloride(FACl)as an additive into(4-FPEA)2MA4Pb5I16 perovskite.On the one hand,the addition of FACl narrows the bandgap through cation exchange between MA^(+)and FA^(+),thereby extending the light absorption range and enhancing photocurrent generation.On the other hand,this MA^(+)/FA^(+)cation exchange decelerates the sublimation of methylammonium chloride and prolongs the crystallization of LDRP perovskite,leading to higher crystallinity and better film quality with a decreased trap-state density.Consequently,this approach led to a remarkable PCE of 20.46%for=5 LDRP perovskite solar cells(PSCs),ranking among the highest for MA/FA mixed lowdimensional PSCs reported to date.Remarkably,our PSCs maintained 90%and 92%of the initial efficiency even after 1300 h at(60±5)℃and(60±5)%relative humidity,respectively.This work promotes the development of LDRP PSCs with excellent efficiency and environmental stability for potential commercial application.
Gas transport under confinement exhibits a plethora of physical and chemical phenomena that differ from those observed in bulk media,owing to the deviations of continuum description at the molecular level.In biological systems,gas channels play indispen-sable roles in various physiological functions by regulating gas transport across cell membranes.Therefore,investigating gas trans-port under such confinement is crucial for comprehending cellular physiological activities.Moreover,leveraging these underlying mechanisms can enable the construction of bioinspired artificial nanofluidic devices with tailored gas transport properties akin to those found in biological channels.This review provides a comprehensive summary of confined gas transport mechanisms,focusing on the unique effects arising from nanoconfinement.Additionally,we categorize nanoconfinement spaces based on dimensionality to elucidate their control over gas transport beha-vior.Finally,we highlight the potential of bioinspired smart gas membranes that mimic precise modulation of transportation observed in organisms.To conclude,we present a concise outlook on the challenges and opportunities in this rapidly expanding field.
Hongwei DuanZeyu ZhuangJing YangShengping ZhangLuda Wang
Organic low-dimensional crystals have garnered escalating interests in the realms of miniaturized optoelectronics and integrated photonics.The continual expansion of molecular systems and improvement in experimental conditions have given rise to unconventional organic low-dimensional crystals,which showcase a variety of appealing structure-dependent properties in the realm of organic semiconductors,owing to their adaptable physicochemical characteristics and exceptional optoelectronics performance.Simultaneously,the development of unconventional low-dimensional crystals is filled with abundant possibilities due to their diverse application prospects.Herein,we present a comprehensive overview of advancements in research on representative cases of unconventional low-dimensional organic crystals,using a systematic and rational structural classification.Finally,we have also discussed the existing challenges and future directions,aspiring to deepen understanding and encourage further research exploration in this field.
Jin FengMao SunYing-Xin MaZhen-Yu GengChuan-Zeng WangShu-Ping ZhuoShu-Hai ChenHong-Tao LinXue-Dong Wang
Low-dimensional materials,with highly tunable electronic structures depending on their sizes and shapes,can be exploited as fundamental building blocks to construct higher-order structures with tailored emergent properties.This is akin to molecules or crystals that are assembled by atoms with diverse symmetries and interactions.Prominent low-dimensional materials developed in recent decades include zero-dimensional(0D)quantum dots,one-dimensional(1D)carbon nanotubes,and two-dimensional(2D)van der Waals materials.These materials enclose a vast diversity of electronic structures ranging from metals and semimetals to semiconductors and insulators.Moreover,low-dimensional materials can be assembled into higher-order architectures known as superlattices,wherein collective electronic and optical behaviors emerge that are absent in the individual building blocks alone.Superlattices composed of interacting low-dimensional entities thus define an ultra-manipulatable materials platform for realizing artificial structures with customizable functionalities.Here,we review significant milestones and recent progress in the field of low-dimensional materials and their superlattices.We survey recently observed exotic emergent electronic and optical properties in these materials and delve into the underlying mechanisms driving these phenomena.Additionally,we hint the future opportunities and remaining challenges in advancing this exciting area of research.