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Photopyroelectric‐based circularly polarized light (CPL) detection, coupling the pyro‐phototronic effect and chiroptical phenomena, has provided a promising platform for high‐performance CPL detectors. However, as a novel detection strategy, photopyroelectric‐based CPL detection is currently restricted by the short‐wave optical response, underscoring the urgent need to extend its response range. Herein, visible‐to‐near‐infrared CPL detection induced by the pyro‐phototronic effect is first realized in chiral‐polar perovskites. Specifically, chiral‐polar multilayered perovskites (S‐BPEA)2FAPb2I7 (1‐S, S‐BPEA = (S)‐1‐4‐Bromophenylethylammonium, FA = formamidinium) with spontaneous polarization shows intrinsic pyroelectric and photopyroelectric performance. Strikingly, combining its merits of the pyro‐phototronic effect and intrinsic wide‐spectrum spin‐selective effect, chiral multilayered 1‐S presents efficient photopyroelectric‐based broadband CPL detection performance spanning 405–785 nm. This research first realizes photopyroelectric‐based infrared CPL detection and also sheds light on developing high‐performance broadband CPL detectors based on the pyro‐phototronic effect in the fields of optics, optoelectronics, and spintronics. [ABSTRACT FROM AUTHOR]

The anomalous photovoltaic (APV) effect in organic–inorganic hybrid perovskites (OIHPs) has attracted massive interest for developing high‐performance optoelectronic devices. However, exploring the ionizing radiation responsive APV effect remains blank, let alone its potential applications. Herein, the unprecedented APV behavior in a 1D lead‐free OIHP, (4‐AMP)BiI5 (ABI, 4‐AMP = 4‐(aminomethyl)pyridine) under X‐ray irradiation is reported, exhibiting a large above‐bandgap bulk photovoltage of ≈10 V. Such a strong APV effect is closely related to the intrinsic electric polarization in polar ABI, which acts as the driving force for X‐ray‐generated carriers' separation and transport, thus allowing it to be self‐powered. As a result, sensitive self‐powered X‐ray detectors based on high‐quality ABI single crystals are successfully fabricated, possessing a high sensitivity of 66.84 µC Gy−1 cm−2, a low detection limit of 482 nGy s−1, and superior operational stability. This work first demonstrates the ionizing radiation‐responsive APV effect in OIHPs, which further enables passive radiation detection. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) organic–inorganic hybrid perovskites (OIHPs) have achieved tremendous success in direct X‐ray detection due to their high absorption coefficient and excellent carrier transport. However, owing to the centrosymmetry of classic 3D structures, these reported X‐ray detectors mostly require external electrical fields to run, resulting in bulky overall circuitry, high energy consumption, and operational instability. Herein, we first report the unprecedented radiation photovoltage in 3D OIHP for efficient self‐driven X‐ray detection. Specifically, the 3D polar OIHP MhyPbBr3 (1, Mhy=methylhydrazine) shows an intrinsic radiation photovoltage (0.47 V) and large mobility‐lifetime product (1.1×10−3 cm2 V−1) under X‐ray irradiation. Strikingly, these excellent physical characteristics endow 1 with sensitive self‐driven X‐ray detection performance, showing a considerable sensitivity of 220 μC Gy−1 cm−2, which surpasses those of most self‐driven X‐ray detectors. This work first explores highly sensitive self‐driven X‐ray detection in 3D polar OIHPs, shedding light on future practical applications. [ABSTRACT FROM AUTHOR]

Circularly polarized light (CPL) detection has wide applications in many fields, where the anisotropy factor (gIph) is an important indicator to characterize the CPL detection performance. So far, many materials with high gIph have been reported, however, the exploration of the regulation of gIph is still in its infancy. Herein, two novel alternating chiral‐achiral cations intercalation‐type chiral hybrid perovskites (CHPs), named (R/S‐1‐phenylpropylamine)(propylamine)PbBr4 (1‐R/S), exhibit above room‐temperature (RT) polar‐phase transition, which greatly regulates the gIph value. The gIph of 1‐R is 0.04 in high‐temperature phase chiral non‐polar (P212121) by applying 5 V bias, interestingly, with the temperature decrease, the gIph value in low‐temperature phase chiral polar (P21) gradually increases (0.22@360K, 0.40@340K, 0.47@320K), and finally reaches a maximum of 0.5 at RT. Such value is not only the highest among 2D CHPs to date, but presents a 12.5‐fold amplification compared with 0.04. Further, this rare phenomenon should be attributed to the built‐in electric field induced by the polar photovoltaic effect, which sheds light on further obtaining CHPs with large gIph. [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]

2D chiral hybrid perovskites have recently emerged as outstanding semiconductor materials. However, most of the reported 2D chiral perovskites have limited structural types and contain high levels of toxic lead, which severely hinders their further applications. Herein, by using a mixed‐cation strategy, an unprecedented type of lead‐free cluster‐based 2D chiral hybrid double perovskite derivatives are successfully obtained, [(R/S‐PPA)4(IPA)6Ag2Bi4I24]·2H2O (1‐R and 1‐S), and [(R/S‐PPA)4(n‐BA)6Ag2Bi4I24]·2H2O (2‐R and 2‐S) (R/S‐PPA=R/S–1‐phenylpropylamine; IPA=isopentylamine; n‐BA=n‐butylamine). Their inorganic skeletons are linked by binuclear {Bi2I10} and infinite chain {Ag2Bi2I14}∞, in which bismuth clusters and multiple coordination modes (e.g., tetrahedral AgI4 and octahedral AgI6) are introduced into the double perovskite system for the first time. This introduction induces distortion of the inorganic layer, which may facilitate the transfer of chirality from the chiral cations into achiral double perovskite skeletons. Further, circular dichroism measurements and circularly polarized light detection confirm their inherent chiral optical activities. In addition, 1‐S exhibits an ultralow X‐ray detection limit of 129.5 nGy s−1, which is 42‐fold lower than that of demands in regular medical diagnosis (5.5 µGy s−1). This study provides a pathway to construct novel type of lead‐free cluster‐based double perovskite derivatives. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic perovskite (HOIP) ferroelectrics with high Curie temperature (Tc), typified by the lead halide hybrid perovskite ferroelectrics, are developing rapidly owing to their maneuverable ferroelectricity at high temperatures. However, acquiring high‐Tc lead‐free HOIP ferroelectrics via rational strategy still needs development. In this study, a brand‐new program by modulating the steric confinement in a cuplike cavity to design high‐Tc bismuth‐halide ferroelectrics [H2mdap]BiX5 (H2mdap = N‐Methyl‐1,3‐Propanediamine, X = Cl (1), Br (2), I(3)) is proposed. Emphatically, the Tc enhanced dramatically from 264 K of 3 to 318 K of 2 and 377 K of 1, induced by the substitution of Br and Cl to I, accompanied with an interesting transition from second‐order phase transition (for 3) to the first‐order one (for 1 and 2). The extent of Tc increase is up to 113 K, which far outweighs that of reported Pb‐halide hybrid ferroelectrics. Structural and computational analyses elucidate that this unprecedented improvement of Tc is due to the higher phase transition energy barriers induced by modulating the steric confinement of cuplike cavity via halogen substitution. These results will provide new inspiration for designing high‐Tc lead‐free HOIP ferroelectrics. [ABSTRACT FROM AUTHOR]

Circular polarized light-dependent anomalous bulk photovoltaic effect - a steady anomalous photovoltaic current can be manipulated by changing the light helicity, is an increasingly interesting topic in contexts ranging from physics to chemistry. Herein, circular polarized light-dependent anomalous bulk photovoltaic effect is presented in achiral hybrid perovskites, (4-AMP)BiI5 (ABI, 4-AMP is 4-(aminomethyl)piperidinium), breaking conventional realization that it can only happen in chiral species. Achiral hybrid perovskite ABI crystallizes in chiroptical-active asymmetric point group m (Cs), showing an anomalous bulk photovoltaic effect with giant photovoltage of 25 V, as well as strong circular polarized light - sensitive properties. Significantly, conspicuous circular polarized light-dependent anomalous bulk photovoltaic effect is reflected in the large degree of dependence of anomalous bulk photovoltaic effect on left-and right-CPL helicity, which is associated with left and right-handed screw optical axes of ABI. Such degree of dependence is demonstrated by a large asymmetry factor of 0.24, which almost falls around the highest value of hybrid perovskites. These unprecedented results may provide a perspective to develop opto-spintronic functionalities in hybrid perovskites. The manipulation of anomalous photovoltaic current by changing the light helicity has attracted an increasing interest in the field. Here, the authors realize circular polarized light-dependent anomalous bulk photovoltaic effect in achiral hybrid perovskites with a large asymmetry factor of 0.24. [ABSTRACT FROM AUTHOR]

A mixed‐cation 3D lead bromide hybrid perovskite (NMDAP)2FAPb4Br13 (1, NMDAP2+ = N‐methyl‐1,3‐diaminopropanium, FA+ = formamidinium) is tailored by incorporating the large NMDAP2+ cation with the small FA+ ion into 3D FAPbBr3. Structurally, the small FA+ ions occupy the prototypical cavities formed by distorted corner‐sharing PbBr6 octahedra as in FAPbBr3, while the bulky NMDAP2+ ions are confined to the expanded lattice which is defined by a new structural motif composed of eight corner‐sharing PbBr6 octahedra and four edge‐sharing octahedra. This localized lattice expansion from FAPbBr3 creates a new branch of the intriguing 3D hybrid perovskite family, breaking the limits of the conventional Goldschmidt tolerance factor rule. Moreover, a high two‐photon absorption (2AP) coefficient of 60.8 cm MW−1 was demonstrated to near‐infrared (NIR) 800 nm illumination, enabling sensitive NIR photoresponses with large on/off ratio (≈104) as well as favorable stability. [ABSTRACT FROM AUTHOR]

Chiral alternating cations intercalation‐type (ACI) perovskites, which are capable of great structural flexibility and a suitable quantum well barrier thickness that facilitates better charge transport, are urgently desired for circularly polarized light (CPL) detection. However, the chiral–polar photovoltaic effect (CPPE) in chiral ACI perovskites has never been reported although CPPE will provide great opportunities for future sustainable development. Here, by transmuting the organic ligands in 2D Ruddlesden–Popper‐type (RP) perovskites, two chiral–polar photovoltaic ACI perovskites (R/S‐PPA)EAPbCl4 (1R/1S) are successfully developed, which are stabilized by the alternating ordering of the short alkyl EA (EA = ethylammonium) and chiral aromatic PPA (PPA = 1‐phenylpropylamine) cations in the interlayer space. Particularly, converting chiral RP into ACI perovskites gives rise to a remarkable CPPE and suitable quantum well barrier thickness. These features contribute to the exploration of self‐powered ultraviolet CPL detection with an asymmetry factor up to 0.4, which reaches the highest value among the reported layered chiral perovskites. This is thought to be the first realization of CPPE in ACI perovskites, which paves the way for the application of chiral perovskites for self‐powered short‐wave ultraviolet CPL detection. [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]

Electrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration. Nevertheless, most known electrocaloric materials exhibit relatively poor cooling performance near room temperature, which hinders their further applications. The emerging family of hybrid perovskite ferroelectrics, which exhibits superior structural diversity, large heat exchange and broad property tenability, offers an ideal platform. Herein, we report an exceptionally large electrocaloric effect near room temperature in a designed hybrid perovskite ferroelectric [(CH3)2CHCH2NH3]2PbCl4, which exhibits a sharp first-order phase transition at 302 K, superior spontaneous polarization (>4.8 μC/cm2) and relatively small coercive field (<15 kV/cm). Strikingly, a large isothermal entropy change ΔS of 25.64 J/kg/K and adiabatic temperature change ΔT of 11.06 K under a small electric field ΔE of 29.7 kV/cm at room temperature are achieved, with giant electrocaloric strengths of isothermal ΔS/ΔE of 0.86 J·cm/kg/K/kV and adiabatic ΔT/ΔE of 370 mK·cm/kV, which is larger than those of traditional ferroelectrics. This work presents a general approach to the design of hybrid perovskite ferroelectrics, as well as provides a family of candidate materials with potentially prominent electrocaloric performance for room temperature solid-state refrigeration. Most known electrocaloric materials show relatively poor cooling performance near room temperature, hindering their applications. Here, the authors achieve large electrocaloric effect near room temperature in a hybrid perovskite ferroelectric, useful for high-performance solid-state refrigeration. [ABSTRACT FROM AUTHOR]

Halide hybrid perovskites are attracting considerable attention as highly promising candidates for directly sensing X‐ray radiation, but it is challenging to realize passive X‐ray detection without an external power supply. However, the bulk photovoltaic effect (BPVE) in ferroelectrics promotes the independent separation of photoexcited carriers. Herein, by dimensionality reconstruction of a pure‐two‐dimensional (P‐2D) monolayered perovskite (CH3OC3H9N)2PbBr4, we obtained a quasi‐two‐dimensional (Q‐2D) ferroelectric (CH3OC3H9N)2CsPb2Br7. Converting P‐2D into Q‐2D perovskite stimulates a significant BPVE associated with robust ferroelectricity, as well as an enhanced mobility lifetime product. These features show the potential of the first passive X‐ray detector based on ferroelectrics with an impressive sensitivity up to 410 μC Gy−1 cm−2 at zero bias, which is even superior to the value of the state‐of‐the‐art α‐Se detector operated at relatively high bias. [ABSTRACT FROM AUTHOR]

Polarization‐sensitive ultraviolet (UV) photodetection is highly indispensable in military and civilian applications and has been demonstrated with various wide‐band photodetectors. However, it still remains elusive to achieve the self‐powered devices, which can be operated in the absence of external bias. Herein, for the first time, ferroelectricity‐driven self‐powered photodetection towards polarized UV light was successfully demonstrated in a 2D wide‐band gap hybrid ferroelectric (BPA)2PbBr4 (BPA=3‐bromopropylammonium) (1). We found that the prominent spontaneous polarization in 1 results in a bulk photovoltaic effect (BPVE) of 0.85 V, that independently drives photoexcited carriers separation and transport and thus supports self‐powered ability. This self‐powered detector shows strong polarization sensitivity to linearly polarized UV illumination with a polarization ratio up to 6.8, which is superior to that of previously reported UV‐polarized photodetectors (ZnO, GaN, and GeS2). [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]

Halide double perovskites have recently bloomed as the green candidates for optoelectronic applications, such as X‐ray detection. Despite great efforts, the exploration of promising organic–inorganic hybrid double perovskites toward X‐ray detection remains unsuccessful. Now, single crystals of the lead‐free hybrid double perovskite, (BA)2CsAgBiBr7 (BA+ is n‐butylammonium), featuring the unique 2D multilayered quantum‐confined motif, enable quite large μτ (mobility‐lifetime) product up to 1.21×10−3 cm2 V−1. This figure‐of‐merit realized in 2D hybrid double perovskites is unprecedented and comparable with that of CH3NH3PbI3 wafers. (BA)2CsAgBiBr7 crystals also exhibit other intriguing attributes for X‐ray detection, including high bulk resistivity, low density of defects and traps, and large X‐ray attenuation coefficient. Consequently, a vertical‐structure crystal device under X‐ray source yields a superior sensitivity of 4.2 μC Gyair−1 cm−2. [ABSTRACT FROM AUTHOR]

Inorganic–organic hybrid perovskites, especially two‐dimensional (2D) layered halide perovskites, have attracted significant attention due to their unique structures and attractive optoelectronic properties, which open up a great opportunity for next‐generation photosensitive devices. Herein, we report a new 2D bilayered inorganic–organic hybrid perovskite, (C6H13NH3)2(NH2CHNH2)Pb2I7 (HFA, where C6H13NH3+ is hexylaminium and NH2CHNH2+ is formamidinium), which exhibits a remarkable photoresponse under broadband light illumination. Structural characterizations demonstrate that the 2D perovskite structure of HFA is constructed by alternant stacking of inorganic lead iodide bilayered sheets and organic hexylaminium layers. Optical absorbance measurements combined with density functional theory (DFT) calculations suggest that HFA is a direct band gap semiconductor with a narrow band gap (Eg) of ≈2.02 eV. Based on these findings, photodetectors based on HFA crystal wafer are fabricated, which exhibit fascinating optoelectronic properties including large on/off current ratios (over 103), fast response speeds (τrise=310 μs and τdecay=520 μs) and high responsivity (≈0.95 mA W−1). This work will contribute to the design and development of new two‐dimensional bilayer inorganic–organic hybrid perovskites for high‐performance photosensitive devices. [ABSTRACT FROM AUTHOR]

Abstract: Although organic‐inorganic hybrid perovskites demonstrate promising potentials for photodetection, one great challenge still to be addressed is their relatively low responding speed (often at the magnitude order of ∼ms). Herein, a solution‐processed photodetector based on polar two‐dimensional (2D) multilayered hybrid perovskite crystal is fabricated, (C5H11NH3)2(CH3NH3)Pb2I7 (EMA, where C5H11NH3+ is n‐pentylaminium), which exhibits an ultrafast responding time of ≈1.52 μs. This figure‐of‐merit is faster at least by 2–4 orders than other reported 2D organic‐inorganic hybrid perovskite photodetectors. To the best of knowledge, this is the record‐fast response‐speed for lateral‐type devices of 2D organic‐inorganic hybrid perovskite. Such ultrafast responding can be attributed to the high crystallinity and quite low density of defects and traps. In addition, this device also presents a high photocurrent on/off ratio (>103) and extremely low dark current (≈10−10 A), indicating its potential applications for high‐efficiency photodetectors. Our results pave the pathway toward ultrafast responding photodetection of 2D organic‐inorganic hybrid perovskites. [ABSTRACT FROM AUTHOR]

Abstract: Cesium‐lead halide perovskites (e.g. CsPbBr3) have gained attention because of their rich physical properties, but their bulk ferroelectricity remains unexplored. Herein, by alloying flexible organic cations into the cubic CsPbBr3, we design the first cesium‐based two‐dimensional (2D) perovskite ferroelectric material with both inorganic alkali metal and organic cations, (C4H9NH3)2CsPb2Br7 (1). Strikingly, 1 shows a high Curie temperature (Tc=412 K) above that of BaTiO3 (ca. 393 K) and notable spontaneous polarization (ca. 4.2 μC cm−2), triggered by not only the ordering of organic cations but also atomic displacement of inorganic Cs+ ions. To our knowledge, such a 2D bilayered Cs+‐based metal–halide perovskite ferroelectric material with inorganic and organic cations is unprecedented. 1 also shows photoelectric semiconducting behavior with large “on/off” ratios of photoconductivity (>103). [ABSTRACT FROM AUTHOR]

We report a new lead-free perovskite-like hybrid, composed of hexamethyleneimine and one-dimensional [SbCl5]n2− polyanionic zigzag chains, which shows above-room-temperature switching of quadratic nonlinear optical (NLO) properties induced by the unique order–disorder conformational changes of the organic cation. [ABSTRACT FROM AUTHOR]

Abstract: Organic–inorganic hybrid perovskites, with the formula ABX3 (A=organic cation, B=metal cation, and X=halide; for example, CH3NH3PbI3), have diverse and intriguing physical properties, such as semiconduction, phase transitions, and optical properties. Herein, a new ABX3‐type semiconducting perovskite‐like hybrid, (hexamethyleneimine)PbBr3 (1), consisting of one‐dimensional inorganic frameworks and cyclic organic cations, is reported. Notably, the inorganic moiety of 1 adopts a perovskite‐like architecture and forms infinite columns composed of face‐sharing PbBr6 octahedra. Strikingly, the organic cation exhibits a highly flexible molecular configuration, which triggers an above‐room‐temperature phase transition, at Tc=338.8 K; this is confirmed by differential scanning calorimetry (DSC), specific heat capacity (Cp), and dielectric measurements. Further structural analysis reveals that the phase transition originates from the molecular configurational distortion of the organic cations coupled with small‐angle reorientation of the PbBr6 octahedra inside the inorganic components. Moreover, temperature‐dependent conductivity and UV/Vis absorption measurements reveal that 1 also displays semiconducting behavior below Tc. It is believed that this work will pave a potential way to design multifeatured perovskite hybrids by utilizing cyclic organic amines. [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]

Perovskite hybrids of lead organometal halides, most notably CH3NH3PbI3, have shown extremely promising applications in the field of optoelectronics, because of their remarkable semiconducting and light-absorbing properties. However, two key issues-the toxicity of lead and the poor ambient instabilities-have restrained their further commercialization. Herein, we have designed a new stable polar lead-free hybrid material by utilizing the strategy of cation substitution, [(CH3)3N]3Bi2I9 ( 1), which adopts the 0D inorganic perovskite-like architecture by face-sharing BiI6 octahedra. It is interesting that 1 displays excellent absorbing properties with a narrow optical band gap of ≈2.0 eV, and positive temperature-dependent conductivity confirms its semiconducting behaviors. In addition, 1 has good phase stability against decomposition under ambient conditions, much superior to that of CH3NH3PbI3. This work suggests the potential of 1 as a lead-free semiconducting absorber with high phase stability for photoelectric applications. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered hybrid perovskites have shown great potential in optoelectronics, owing to their unique physical attributes. However, 2D hybrid perovskite ferroelectrics remain rare. The first hybrid ferroelectric with unusual 2D multilayered perovskite framework, (C4H9NH3)2(CH3NH3)2Pb3Br10 ( 1), has been constructed by tailored alloying of the mixed organic cations into 3D prototype of CH3NH3PbBr3. Ferroelectricity is created through molecular reorientation and synergic ordering of organic moieties, which are unprecedented for the known 2D multilayered hybrid perovskites. Single-crystal photodetectors of 1 exhibit fascinating performances, including extremely low dark currents (ca. 10−12 A), large on/off current ratios (ca. 2.5×103), and very fast response rate (ca. 150 μs). These merits are superior to integrated detectors of other 2D perovskites, and compete with the most active CH3NH3PbI3. [ABSTRACT FROM AUTHOR]

Perovskite lead halides (CH3NH3PbI3) have recently taken a promising position in photovoltaics and optoelectronics because of remarkable semiconducting properties and possible ferroelectricity. However, the potential toxicity of lead arouses great environmental concern for widespread application. A new chemically tailored lead-free semiconducting hybrid ferroelectric is reported, N-methylpyrrolidinium)3Sb2Br9 ( 1), which consists of a zero-dimensional (0-D) perovskite-like anionic framework connected by corner- sharing SbBr6 coordinated octahedra. It presents a large ferroelectric spontaneous polarization of approximately 7.6 μC cm−2, as well as notable semiconducting properties, including positive temperature-dependent conductivity and ultraviolet-sensitive photoconductivity. Theoretical analysis of electronic structure and energy gap discloses a dominant contribution of the 0-D perovskite-like structure to the semiconducting properties of the material. This finding throws light on the rational design of new perovskite-like hybrids, especially lead-free semiconducting ferroelectrics. [ABSTRACT FROM AUTHOR]

Perovskite-type ferroelectrics composed of organometallic halides are emerging as a promising alternative to conventional photovoltaic devices because of their unique photovoltaic effects (PVEs). A new layered perovskite-type photoferroelectric, bis(cyclohexylaminium) tetrabromo lead ( 1), is presented. The material exhibits an exceptional anisotropy of bulk PVEs. Upon photoexcitation, superior photovoltaic behaviors are created along its inorganic layers, which are composed of corner-sharing PbBr6 octahedra. Semiconducting activity with remarkable photoconductivity is achieved in the vertical direction, showing sizeable on/off current ratios (>104), which compete with the most active photovoltaic material CH3NH3PbI3. In 1 the temperature-dependence of photovoltage coincides fairly well with that of polarization, confirming the dominant role of ferroelectricity in such highly anisotropic PVEs. This finding sheds light on bulk PVEs in ferroelectric materials, and promotes their application in optoelectronic devices. [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 hybrid perovskites, with their high X‐ray absorption and extended carrier transport, present excellent promise for efficient direct X‐ray detection. However, most of the current devices require external bias voltage, which results in the need for significant energy consumption and severe ion migration, therefore, it is urgent to develop new types of materials for achieving efficient passive X‐ray detection. Herein, two novel chiral polar alternating cations intercalation (ACI)‐type hybrid perovskite materials, named (R/S‐PPA)(IEA)PbBr4 (1‐R/S, (R/S)‐PPA = R/S‐1‐phenylpropylamine; IEA = iodoethylamine), are constructed by integrating the chiral aromatic spacer R/S‐PPA and the iodine‐substituted spacer IEA. Various intermolecular interactions, such as I···I, C─H···I, π···π interactions, are introduced due to the introduction of I‐substituted chain amines, which effectively suppresses ion migration and thus lead to improved operational stability. The device constructed along the polar axis displays superior X‐ray detection performance, such as relatively high sensitivity and an ultra‐low limit of detection (LoD) of 3.0 nGy s−1, making it the first chiral ACI‐type perovskite material for realizing efficient passive X‐ray detection. Furthermore, 1‐R also presents low dark current drift and exceptional irradiation stability. This work provides new thought for using novel ACI‐type polar perovskite for high‐performance passive direct X‐ray detection. [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]

Perovskite ferroelectrics with prominent nonlinear optical absorption have attracted great attention in the field of photonics. However, they are traditionally dominated by inorganic oxides and exhibit relatively small nonlinear optical absorption coefficients, which hinder their further applications. Herein, we report a new organic--inorganic hybrid bilayered perovskite ferroelectric, (C4H9NH3)2(NH2CHNH2)Pb2Br7 (1), showing an above-room-temperature Curie temperature (~322 K) and notable spontaneous polarization (~3.8 μC cm--2). Significantly, the unique quantum-well structure of 1 results in intriguing two-photon absorption properties with a giant nonlinear optical absorption coefficient as high as 5.76 X 103 cm GW--1, which is almost two-orders of magnitude larger than those of mostly traditional all-inorganic perovskite ferroelectrics. To our best knowledge, 1 is the first example of hybrid ferroelectrics with giant two-photon absorption coefficient. The mechanisms for ferroelectric and two-photon absorption are revealed. This work will shed light on the design of new ferroelectrics with two-photon absorption and promote their potentials in the photonic application. [ABSTRACT FROM AUTHOR]