Search

Chiral hybrid perovskites (CHPs) with inherent chirality, dimensional tunability, and excellent semiconducting features are proved to be an ideal platform to study spin and helicity‐related physical phenomenon. However, due to their intrinsic thermodynamic unfavorability, there are many CHPs with exotic structures, such as superlattice‐type 2D heterostructures, which are covered by their transient lifespan caused by phase instability during the crystallization process. This limitation hinders the attempt to further explore and understand the chiral structure‐function relationship. Here, CHPs (R/SCPEA)2PbI4·(R/SCPEA)2FAPb2I7 (R/S1‐2, R/S‐CPEA = (R/S)‐1‐(4‐chlorophenyl)ethylammonium FA = formidinum) is obtained with asymmetric multiple‐quantum‐well architectures through kinetically‐controlled self‐assembly. Structural analysis identified the unique natural monolayer‐bilayer recurring heterostructures of 1–2 with sub‐nanometer accuracy and potentially non‐degenerate chiral environment. Such novel structures in 1–2 provide them fascinating multiple absorption‐emission features. Meanwhile, the chirality of 1–2 is confirmed by vibrational circular dichroism and angle‐dependent photocurrent measurement, provoking its potential in chiral optoelectronic devices. The work extends the understanding of CHP growth and will stimulate further exploration and synthesis of extraordinary chiral heterostructures, which may pave the way for the development of chiral optoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

Solution‐processable perovskite‐based devices are potentially very interesting because of their relatively cheap fabrication cost but outstanding optoelectronic performance. However, the solution spin‐coating process involves complicated processes, including perovskite solution droplets, nucleation of perovskite, and formation of intermediate perovskite films, resulting in complicated crystallization pathways for perovskite films under annealing. Understanding and therefore controlling the fabrication process of perovskites is difficult. Recently, synchrotron radiation‐based in situ grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) techniques, which possess the advantages of high collimation, high resolution, and high brightness, have enabled to bridge complicated perovskite structure information with device performance by revealing the real‐time crystallization pathways of perovskites during the spin‐coating process. Herein, the developments of synchrotron radiation‐based in situ GIWAXS are discussed in the study of the crystallization process of perovskites, especially revealing the important crystallization mechanisms of state‐of‐the‐art perovskite optoelectronic devices with high performance. At the end, several potential applications and challenges associated with in situ GIWAXS techniques for perovskite‐based devices are highlighted. [ABSTRACT FROM AUTHOR]

Broadband photodetectors (PDs) with low detection limits hold significant importance to next‐generation optoelectronic devices. However, simultaneously detecting broadband (i.e., X‐ray to visible regimes) and weak lights in a single semiconducting material remains highly challenging. Here, by alloying iodine‐substituted short‐chain cations into the 3D FAPbI3 (FA = formamidine), a new 2D bilayered lead iodide hybrid perovskite, (2IPA)2FAPb2I7 (1, 2IPA = 2‐iodopropylammonium), that enables addressing this challenge is reported. Such a 2D multilayered structure and lead iodide composition jointly endow 1 with a minimized dark current (6.04 pA), excellent electrical property, and narrow bandgap (2.03 eV), which further gives it great potential for detecting broadband weak lights. Consequently, its high‐quality single crystal PDs exhibit remarkable photoresponses to weak ultraviolet–visible lights (377–637 nm) at several tens of nW cm−2 with high responsivities (>102 mA W−1) and significant detectivities (>1012 Jones). Moreover, 1 has an excellent X‐ray detection performance with a high sensitivity of 438 µC Gy−1 cm−2 and an ultralow detection limit of 20 nGy s−1. These exceptional attributes make 1 a promising material for broadband weak lights detection, which also sheds light on future explorations of high‐performance PDs based on 2D hybrid perovskites. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) has recently caught increasing attention owing to its widespread applications from 3D display to quantum‐based optical computation. Among various CPL‐active materials, low‐dimensional hybrid perovskites have risen to prominence, benefiting from their excellent structural flexibility and optoelectronic properties. However, the exploration of hybrid perovskites with white‐CPL remains a challenge and most of them suffer from moisture instability. Here, a pair of moisture‐resistant 1D hybrid perovskites, (R‐C5H14N2)PbBr4·H2O (1R) and (S‐C5H14N2)PbBr4·H2O (2S), are reported in which [PbBr42−]∞ double chains are surrounded by chiral cations and water molecules forming the bulk assembled quantum‐helix structures. The strong quantum confinement in these unique structures facilitates exciton self‐trapping, which further synergizes the effect of chiral cations, endowing 1R and 2S with opposite broadband yellowish white‐CPL with a luminescence dissymmetry factor (glum) of 1.8 × 10−3 and a color rendering index up to 81. Notably, the dehydrated 1R can be recovered in humid air (60% relative humidity) within a few minutes via reabsorption of water molecules, exhibiting excellent moisture resistance, which is much better than most reported hybrid perovskites. A new path is paved here to further exploration of moisture‐resistant CPL‐active materials for multifunctional applications. [ABSTRACT FROM AUTHOR]

Polarization-sensitive photodetection is central to optics applications and has been successfully demonstrated in photodetectors of two-dimensional (2D) materials, such as layered hybrid perovskites; however, achieving high polarization sensitivity in such a photodetector remains extremely challenging. Here, for the first time, we demonstrate a high-performance polarization-sensitive photodetector using single-crystalline 2D/3D perovskite heterostructure, namely, (4-AMP)(MA)2Pb3Br10/MAPbBr3 (MA = methylammonium; 4-AMP = 4-(aminomethyl)piperidinium), which exhibits ultrahigh polarization sensitivity up to 17.6 under self-driven mode. To our knowledge, such a high polarization selectivity has surpassed all of the reported perovskite-based devices, and is comparable to, or even better than, the traditional inorganic heterostructure-based photodetectors. Further studies reveal that the built-in electric field formed at the junction can spatially separate the photogenerated electrons and holes, reducing their recombination rate and thus enhancing the performance for polarization-sensitive photodetection. This work provides a new source of polarization-sensitive materials and insights into designing novel optoelectronic devices. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskite heterostructures, particularly 2D/3D perovskite heterostructures, have enjoyed great success in optoelectronic field. However, the photodetection performance of those heterostructures is obscured by extensive disorder in their polycrystalline films. Here, a delicate solution method is demonstrated for creating a sizable crystal of vertical 2D/3D perovskite heterostructure featuring a well‐defined interface and high single‐crystalline quality, namely (4‐AMP)(MA)2Pb3Br10/MAPbBr3 (MA, methylammonium; 4‐AMP, 4‐(aminomethyl)piperidinium). These high‐quality crystals are ideal mediums for charge transport and exploiting their optoelectronic properties. Electrical transport measurements demonstrate that the (4‐AMP)(MA)2Pb3Br10/MAPbBr3 heterostructure can form vertical diode with obvious current rectification behavior and excellent photocurrent generation characteristics. Strikingly, benefitting from the built‐in electrical potential at the junction, photodetectors based on those millimeter‐thickness heterostructure crystals exhibit high performance in self‐driven operation mode, including large on/off switching radio (≈105), fast response time (600/600 µs), and high detectivity (≈1012). This work enables an important advance in the development of single‐crystalline perovskite heterostructures for both fundamental demonstrations and high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Self‐powered photodetection driven by ferroelectric polarization has shown great potential in next‐generation optoelectronic devices. Hybrid perovskite ferroelectrics that combine polarization and semiconducting properties have a promising position within this portfolio. Herein, we demonstrate the realization of self‐powered photodetection in a new developed biaxial ferroelectric, (EA)2(MA)2Pb3Br10 (1, EA is ethylammonium and MA is methylammonium), which displays high Curie temperature (375 K), superior spontaneous polarization (3.7 μC cm−2), and unique semiconducting nature. Strikingly, without an external energy supply, 1 exhibits an direction‐selectable photocurrent with fascinating attributes including high photocurrent density (≈4.1 μA cm−2), high on/off switching ratio (over 106), and ultrafast response time (96/123 μs); such merits are superior to those of the most active ferroelectric oxide BiFeO3. Further studies reveal that strong inversion symmetry breaking in 1 provides a desirable driving force for carrier separation, accounting for such electrically tunable self‐powered photoactive behaviors. This work sheds light on exploring new multifunctional hybrid perovskites and advancing the design of intelligent photoelectric devices. [ABSTRACT FROM AUTHOR]

Abstract: Large‐size crystals of organic–inorganic hybrid perovskites (e.g., CH3NH3PbX3, X = Cl, Br, I) have gained wide attention since their spectacular progress on optoelectronic technologies. Although presenting brilliant semiconducting properties, a serious concern of the toxicity in these lead‐based hybrids has become a stumbling block that limits their wide‐scale applications. Exploring lead‐free hybrid perovskite is thus highly urgent for high‐performance optoelectronic devices. Here, a new lead‐free perovskite hybrid (TMHD)BiBr5 (TMHD = N,N,N,N‐tetramethyl‐1,6‐hexanediammonium) is prepared from facile solution process. Emphatically, inch‐size high‐quality single crystals are successfully grown, the dimensions of which reach up to 32 × 24 × 12 mm3. Furthermore, the planar arrays of photodetectors based on bulk lead‐free (TMHD)BiBr5 single crystals are first fabricated, which shows sizeable on/off current ratios (≈103) and rapid response speed (τrise = 8.9 ms and τdecay = 10.2 ms). The prominent device performance of (TMHD)BiBr5 strongly underscores the lead‐free hybrid perovskite single crystals as promising material candidates for optoelectronic applications. [ABSTRACT FROM AUTHOR]

X‐ray detectors with high sensitivity are of great significance in both civil and military fields. Over the past decades, great efforts have been made to improve the sensitivity in conventional inorganic materials, but mainly at the cost of increasing the energy consumption with a quite high operating voltage. Developing photosensitive ferroelectrics directly as detector materials may be a conceptually new strategy in view of the strong ferroelectric spontaneous polarization (Ps) that assists photoinduced carriers separation and transport. A high‐performance X‐ray detector in 2D hybrid halide perovskite ferroelectric (C4H9NH3)2(C2H5NH3)2Pb3Br10 (BA2EA2Pb3Br10) (Ps = 5 µC cm−2) is fabricated and exhibits an ultrahigh X‐ray sensitivity up to 6.8 × 103 µC Gyair−1 cm−2 even at a relatively low operating voltage, which is over 300‐fold larger than that of state‐of‐the‐art α‐Se X‐ray detectors. Such a brilliant figure‐of‐merit is largely attributed to the superior mobility–lifetime products associated with the strong ferroelectric polarization of BA2EA2Pb3Br10. As pioneering work, these findings inform the exploration of hybrid halide perovskite ferroelectrics toward high‐performance photoelectronic devices. [ABSTRACT FROM AUTHOR]

2D organic–inorganic hybrid perovskites are emerging as the promising alternatives in photodetection, due to their unique merits stemming from intrinsic quantum‐confined structures. Despite great ongoing effects, highly sensitive and ultrafast responding photodetectors of 2D hybrid perovskites remain a huge blank. Here, the first nanosecond‐responsive array photodetector based on 2D perovskite crystals of (PA)2(G)Pb2I7 (where PA = n‐pentylaminium and G = guanidinium) is fabricated, which features a newly tailored bilayer motif with large‐size G cation as "perovskiter" inside the distorted PbI3 perovskite framework. This motif creates a new branch of the intriguing 2D hybrid perovskite family. Strikingly, both high photodetectivities (6.3 × 1012 Jones) and responsivities (≈47 A W−1), as well as low dark current (≈2.4 × 10−11 A), are achieved in this array photodetector. Further, its ultrafast response time (τ) of 3.1 ns is one of the record‐fast merits for 2D hybrid perovskites. Such attributes originate from its strong in‐plane photoresponse related to perovskite network and low dark current inhibited by the hopping barriers of insulating PA bilayers. All these characteristics make (PA)2(G)Pb2I7 a promising candidate for photodetection, and pave the way to explore new 2D hybrid perovskite candidates for future high‐performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

Luminescent ferroelectrics have attracted considerable attention in terms of integrated photoelectronic devices, most of which are focused on the multicomponent systems of rare‐earth doping ferroelectric ceramics. However, bulk ferroelectricity with coexistence of strong white‐light emission, especially in the single‐component system, remains quite rare. Here, a new organic–inorganic hybrid ferroelectric of (C4H9NH3)2PbCl4 (1) is reported, adopting a 2D layered perovskite architecture, which exhibits an unprecedented coexistence of notable ferroelectricity and intrinsic white‐light emission. Decent above‐room‐temperature spontaneous polarization of ≈2.1 µC cm−2 is confirmed for 1. Particularly, it also exhibits brilliant broadband white‐light emission with a high color‐rendering‐index up to 86 under UV excitation. Structural analyses indicate that ferroelectricity of 1 originates from molecular reorientation of dynamic organic cations, as well as significant structural distortion of PbCl6 octahedra that also contribute to its white‐light emission. This work paves an avenue to design new hybrid ferroelectrics for multifunctional application in the photoelectronic field. A 2D organic–inorganic perovskite ferroelectric (C4H9NH3)2PbCl4 is prepared, which exhibits unprecedented coexistence of strong spontaneous polarization and intriguing white‐light emission. [ABSTRACT FROM AUTHOR]