Search

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]

Halide perovskite photoferroelectrics, materials possessing both photosensitive and ferroelectric properties, have motivated tremendous attention in the past decade owing to their distinguishing bulk photovoltaic effect (BPVE) and cross‐coupled functionalities. Despite the great achievements, the BPVE coupled functionalities are still limited by the geometric origin contradictory of internal order parameters. Herein, by exploiting a geometrical design approach, a soft layered halide perovskite improper photoferroelectric (2FEA)2(EA)2Pb3Br10 (1, where 2FEA is 2,2‐difluoroethylamonium and EA is ethylammonium) has been developed. Crystallographic investigations reveal that the incorporation of large‐size EA cations significantly induces a nonpolar lattice distortion of the inorganic semiconducting framework, which gives rise to a striking improper ferroelectricity. In the soft crystal lattices, driven by the subtle competition and coupling between photoinduced carriers and inorganic lattice distortions, single crystals of 1 display a giant cross‐coupled photostriction with a considerable photostrictive coefficient up to 4.89 × 10−6 m2 W−1, which is larger than the traditional semiconductors and ferroelectrics. This work offers an attractive route to the design of new improper photoferroelectric materials and promotes their further applications in photoelectronic devices. [ABSTRACT FROM AUTHOR]

Bulk photovoltaic effect, a promising optoelectronic phenomenon for generating polarized dependent steady‐state photocurrent, has been widely applied in various photodetectors. However, incorporating stereochemically active lone pair to construct bulk photovoltage in organic‐inorganic hybrid perovskite (OIHP) is still elusive and challenging. Herein, bulk photovoltage (1.2 V) has been successfully achieved by introducing the stereo‐chemically active lone pair perovskitizer to construct a polar tri‐layered hybrid perovskite, namely, (IBA)2MHy2Pb3Br10 (1, IBA=iso‐butylamine, MHy=methylhydrazine). Strikingly, owning to the promising bulk photovoltage, 1‐based detectors exhibit an ultra‐highly sensitive polarized photodetection (polarization ratio of up to 24.6) under self‐powered mode. This ratio surpasses all the reported two‐dimension OIHP single‐crystal photodetectors. In addition, detectors exhibit outstanding responsivity (≈200 mA W−1) and detectivity (≈2.4×1013 Jones). More excitingly, further investigation confirms that lone pair electrons in MHy+ result in the separation of positive and negative charges to produce directional dipoles, which further directional alignment to generate bulk photovoltage, thereby resulting in polarization‐dependent photocurrent. Our findings provide a new demonstration for polar multilayer materials' construction and may open opportunities for a host of high‐sensitive polarized photodetection. [ABSTRACT FROM AUTHOR]

Photoferroelectrics, especially emerging halide perovskite ferroelectrics, have motivated tremendous interests owing to their fascinating bulk photovoltaic effect (BPVE) and cross‐coupled functionalities. However, solid solutions of halide perovskite photoferroelectrics with controllable structure and enhanced performance are scarcely explored. Herein, through mixing cage cation, a homogeneous halide perovskite photoferroelectric PA2FAxMA1−xPb2Br7 solid solution (PA, FA and MA are CH3CH2CH2NH3+, NH2CHNH2+ and CH3NH3+, 0≤x≤1) has been developed, which demonstrates tunable Curie temperature in a wide range of 263–323 K and excellent optoelectrical features. As the component adjusted to x=0.7, the bulk crystal demonstrates ultrahigh pyroelectric coefficient up to 1.48 μC cm−2 K−1 around room temperature. Strikingly, benefiting from the light‐induced pyroelectricity and remarkable BPVE, a self‐powered and sensitive photodetector based solid solution crystals with boosted responsivity and detectivity over than 1300 % has been achieved. This pioneering work sheds light on the exploration of photoferroelectric solid solutions towards high‐performance photoelectronic devices. [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]

Chiral hybrid perovskites are recently considered for circularly polarized light (CPL) detection owing to the integration of chiral activity and prominent photoelectric characteristics. However, chiral hybrid perovskites are limited because of the restricted chiral cations; efficient self‐driven CPL detection without external power sources required for halide perovskite photodetectors is desirable but remains scarce. Herein, two alternating cations in the interlayer space of chiral‐polar hybrid perovskites, (R‐β‐MPA)EAPbBr4 and (S‐β‐MPA)EAPbBr4 (MPA = methylphenethylammonium and EA = ethylammonium), are developed via a mixed‐cation approach. These perovskites exhibit chiral characteristics featuring CPL detection with high detectivity. Notably, the chiral‐polar structure gives rise to a built‐in electric field to realize self‐driven CPL detection without an applied voltage, and the photocurrent difference reaches 19% under the right and left CPL irradiation. Moreover, a prominent response time of 300 µs is obtained, which is among the fastest for CPL detection. This work highlights the significance of chemical design in the exploration of new chiral perovskites, which will broaden the scope of chiral materials for high‐performance applications. [ABSTRACT FROM AUTHOR]

Polarized‐light detection in the deep ultraviolet solar‐blind region is indispensable for optoelectronic applications. 2D hybrid perovskite ferroelectrics with inherent anisotropy and bulk photovoltaic effect (BPVE) have become a robust candidate in this portfolio. We here report a wide band‐gap 2D perovskite ferroelectric, (isobutylammonium)2(methylamium)Pb2Cl7 (1), in which the BPVE behaves as self‐driving source for solar‐blind ultraviolet polarized‐light detection. It exhibits a large dichroism ratio (≈15.7) and superior BPVE‐directed photocurrent (≈3.6 μA cm−2, under 266 nm). These attributes facilitate excellent self‐powered polarized‐light detection of high on/off contrast (≈103) and polarization ratio (≈2.5), beyond those of inorganic oxides (e.g. ZnO, 1.47; GaN, 1.38). This study highlights potential of 2D perovskite ferroelectrics for new optoelectronic application. [ABSTRACT FROM AUTHOR]

Ferroelectric materials, particularly the emerging layered hybrid ferroelectrics, have shown great potential for high‐sensitive polarization photodetection owing to their striking bulk photovoltaic effect (BPVE). Despite recent great achievements, the linear photoresponse range based on single‐mode BPVE is still limited in the shortwave region due to the large intrinsic bandgaps. Herein, first, the realization of self‐powered visible–infrared polarization photodetection by exploiting dual‐modal BPVE in a newly developed layered Dion–Jacobson (D‐J) hybrid ferroelectric (BDA)(EA)2Pb3Br10 (1, BDA is 1,4‐butadiammonium, EA is ethylammonium) is reported. Crystallographic investigations indicate that 1 adopts a typical trilayered D‐J perovskite structure with a fascinating ferroelectric feature and a giant two‐photon absorption coefficient as giant as 4.73 cm MW–1. Meanwhile, the bulk single crystal device of 1 exhibits excellent self‐powered direct detection performance under both visible light (405 nm) and near‐infrared light (800 nm), with a current on/off ratio as high as 103. More intriguingly, the device displays high sensitivity to the polarization of illuminated light, showing a considerable anisotropy up to 4.2 (405 nm) and 4.8 (800 nm), which are much larger than the detectors achieved by geometry anisotropy. The realization of self‐powered visible‐infrared dual‐modal polarization photodetection in 1 indicates the tremendous potential of hybrid ferroelectrics in various optoelectronic applications. [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]

Through a functional unit‐transmutation strategy, a fatigue‐free layered hybrid perovskite ferroelectric (C6H5CH2NH3)2CsPb2Br7 (BCPB) has been developed, which demonstrates stable spontaneous polarization (Ps) of 6.5 μC cm−2 and high Curie temperature up to 425 K. Meanwhile, BCPB shows splendid bulk photovoltaic effect (BPVE) properties with noticeable zero‐bias photocurrent density (5 μA cm−2), and high on/off switching ratio of current (over 3×105); these merits even overmatch the most known ferroelectric semiconductor BiFeO3. The unique structure with self‐regulated net electrical charged layers gives rise to the fatigue‐free feature of Ps and BPVE (no significant fatigue after 108 polarity switching cycles), promoting the potential applications of BCPB in photovoltaic non‐volatile memories. This work offers an efficient approach for exploring fatigue‐free semiconducting ferroelectrics as well as excavates their further applications in next‐generation electronic devices. [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]

Polarized light detection is attracting increasing attention for its wide applications ranging from optical switches to high‐resolution photodetectors. Two‐dimensional (2D) hybrid perovskite‐type ferroelectrics combining inherent light polarization dependence of bulk photovoltaic effect (BPVE) with excellent semiconducting performance present significant possibilities. Now, the BPVE‐driven highly sensitive polarized light detection in a 2D trilayered hybrid perovskite ferroelectric, (allyammonium)2(ethylammonium)2Pb3Br10 (1), is presented. It shows a superior BPVE with near‐band gap photovoltage of ca. 2.5 V and high on/off switching ratio of current (ca. 104). Driven by the superior BPVE, 1 exhibits highly sensitive polarized light detection with a polarization ratio as high as ca. 15, which is far more beyond than those of structural anisotropy‐based monocomponent devices. This is the first realization of BPVE‐driven polarized light detection in hybrid perovskite ferroelectrics. [ABSTRACT FROM AUTHOR]

Dense Bi(Ni2/3Ta1/3)O3‐PbTiO3 (BNT‐PT) ceramics were prepared by solid‐state reaction method. Morphotropic phase boundary between tetragonal and rhombohedral phase was observed around the composition 0.38BNT‐0.62PT, at which large photovoltages of 13.2V were obtained under 405 nm laser illumination with power density of 200 mW/cm2. By B‐site Ni2+ ions doping, the bandgap values of BNT‐PT solid solutions were reduced to 2.25~1.85 eV, and the anomalous photovoltaic response was extended from the ultraviolet region to a wavelength of 550 nm at the visible light region. [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]