Search

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]

2D Dion–Jacobson (DJ) perovskites recently have attracted extensive attention for X‐ray detection owing to their structural rigidity and environmental stability. The chemical incorporation of π‐conjugation aromatic spacing cations into DJ phase perovskites will increase the rigidity of cation and electron cloud density between adjacent inorganic slabs, thus facilitating structural rigidity and charge transport. However, it is still a challenge to synthesize high‐quality single crystals of DJ phase perovskite with aromatic spacers for detecting X‐ray applications. Here, a new DJ phase perovskite by introducing π‐conjugated aromatic cation spacer, (4ABA)PbI4 (1, 4ABA = 4‐aminobenzylamine), eliminating the van der Waals gap is designed. High‐quality single crystals of 1 are grown via the facile solution method, exhibiting high resistivity (1.97 × 1011 Ω cm), low trap density (3.36 × 109 cm−3), and large carrier mobility‐lifetime product (1.03 × 10−3 cm2 V−1) under X‐ray illumination. Such remarkable physical characteristics endow single crystal 1 detector with high‐performance X‐ray detection including a high sensitivity of 572 µC Gyair−1cm−2, an ultralow detection limit of 7.50 nGyair s−1 and exceptional radiation stability. The X‐ray detection limit of 1 is over 700 times lower than that of routine medical diagnosis (5500 nGyair s−1), demonstrating potential applications in medical examination. [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]

Lead halide perovskites have made great advance in direct X‐ray detection, however the presence of toxic lead and the requirement of high working voltages severely limit their applicability and operational stability. Thus, exploring "green" lead‐free hybrid perovskites capable of detecting X‐rays at zero bias is crucial but remains toughly challenging. Here, utilizing chiral R/S‐1‐phenylpropylamine (R/S‐PPA) cations, a pair of 0D chiral‐polar perovskites, (R/S‐PPA)2BiI5 (1R/1S) are constructed. Their intrinsic spontaneous electric polarization induces a large bulk photovoltage of 0.63 V, which acts as a driving force to separate and transport photogenerated carriers, thus endowing them with the capability of self‐driven detection. Consequently, self‐driven X‐ray detectors with a low detection limit of 270 nGy s−1 are successfully constructed based on high‐quality, inch‐sized single crystals of 1R. Notably, they show suppressed baseline drift under the self‐driven mode, exhibiting superior operational stability. This study realizes self‐driven X‐ray detection in a single‐phase lead‐free hybrid perovskite by exploiting the intrinsic bulk photovoltaic effect, which sheds light on future explorations of lead‐free hybrid perovskites toward "green" self‐driven radiation detectors with high performance. [ABSTRACT FROM AUTHOR]

Chiral halide perovskites have emerged as promising circularly polarized light sources due to their great potential applications in 3D displays, optical data storage, and optical communication devices. However, to date, chiral halide perovskites with efficient blue circularly polarized luminescence (CPL) are scarcely unearthed. Herein, through formamidine engineering to decrease lattice distortion, the first new types of chiral corrugated 2D halide perovskites are presented (R/S)‐(BPEA)FAPbBr4·H2O (2‐R/S) (BPEA = 4‐bromophenylethylaminium, FA = formamidinium). Interestingly, driven by the incorporation of FA organic cations, the chiral perovskite layer realizes the transformation from (100)‐oriented (R/S)‐(BPEA)2PbBr4·H2O (1‐R/S) to (110)‐oriented 2‐R/S accompanying with reduced lattice distortion. More importantly, (110)‐oriented chiral perovskites 2‐R exhibit remarkable blue CPL with large asymmetry factors (glum =8.4 × 10−3). This work offers an exciting approach to realizing efficient blue CPL and promotes their further applications in photoelectronic devices. [ABSTRACT FROM AUTHOR]

Chiral three‐dimensional hybrid organic–inorganic perovskites (3D HOIPs) would show unique chiroptoelectronic performance due to the combination of chirality and 3D structure. However, the synthesis of 3D chiral HOIPs remains a significant challenge. Herein, we constructed a pair of unprecedented 3D chiral halide perovskitoids (R/S‐BPEA)EA6Pb4Cl15 (1‐R/S) (R/S‐BPEA=(R/S)‐1‐4‐Bromophenylethylammonium, EA=ethylammonium), in which the large chiral cations can be contained in the big "hollow" inorganic frameworks induced by mixing cations. Notably, 3D 1‐R/S shows natural chiroptical activity, as evidenced by its significant mirror circular dichroism spectra and the ability to distinguish circularly polarized light. Moreover, based on the unique 3D structure, 1‐S presents sensitive X‐ray detection performance with a low detection limit of 398 nGyair s−1, which is 14 times lower than the regular medical diagnosis of 5.5 μGyair s−1. In this work, 3D chiral halide perovskitoids provide a new route to develop chiral material in spintronics and optoelectronics. [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]