ABSTRACT
The family of polar hybrid perovskites, in which bulk photovoltaic effects (BPVEs) drive steady photocurrent without bias voltage, have shown promising potentials in self-powered polarization-sensitive photodetection. However, reports of BPVEs in 3D perovskites remain scare, being mainly hindered by the limited dipole moment or lack of symmetry breaking. Herein, a polar 3D perovskitoid, (BDA)Pb2 Br6 (BDA = NH3 C4 H8 NH3 ), where the spontaneous polarization (Ps )-induced BPVE drives self-powered photodetection of polarized-light is reported. Emphatically, the edge-sharing Pb2 Br10 dimer building unit allows the optical anisotropy and polarity in 3D (BDA)Pb2 Br6 , which triggers distinct optical absorption dichroism ratio of ≈2.80 and BPVE dictated photocurrent of 3.5 µA cm-2 . Strikingly, these merits contribute to a polarization-sensitive photodetection with a high polarization ratio (≈4) under self-powered mode, beyond those of 2D hybrid perovskites and inorganic materials. This study highlights the potential of polar 3D perovskitoids toward intelligent optoelectronic applications.
ABSTRACT
Halide composition engineering has been demonstrated as an effective strategy for optical and electronic properties modulation in 3D perovskites. While the impact of halide mixing on the structural and charge transport properties of 3D perovskitoids remains largely unexplored. Herein, it is demonstrated that bromine (Br) mixing in 3D (NMPDA)Pb2 I6 (NMPDA = N-methyl-1,3-propane diammonium) perovskitoid yields stabilized (NMPDA)Pb2 I4 Br2 with specific ordered halide sites, where Br ions locate at the edge-sharing sites. The halide ordered structure enables stronger H-bonds, shorter interlayer distance, and lower octahedra distortion in (NMPDA)Pb2 I4 Br2 with respect to the pristine (NMPDA)Pb2 I6 . These attributes further result in high ion migration activation energy, low defect states density, and enhanced carrier mobility-lifetime product (µτ), as underpinned by the electrical properties investigation and DFT calculations. Remarkably, the parallel configured photodetector based on (NMPDA)Pb2 I4 Br2 single crystal delivers a high on/off current ratio of 3.92 × 103 , a satisfying photoresponsivity and detectivity of 0.28 A W-1 and 3.05 × 1012 Jones under 10.94 µW cm-2 irradiation, superior to that of (NMPDA)Pb2 I6 and the reported 3D perovskitoids. This work sheds novel insight on exploring 3D mixed halide perovskitoids toward advanced and stable optoelectronic devices.
ABSTRACT
Broadband emissions from low-dimensional hybrid perovskites have aroused intense interest. However, the achievement of broadband red emission in lead halide perovskites remains challenging. Herein, we report a one-dimensional (1D) hybrid lead bromide perovskitoid, (HM)Pb2Br6 (HM = hexamethonium), featuring a corrugated "3 × 3" [Pb2Br6]2- chain. The unique structure results in intriguingly red emission peaking at 692 nm, with a PLQY of around 6.24%. Our spectroscopic and computational studies reveal that the red emission derives from self-localized Pb23+, Pb3+ and Br2- species confined within the inorganic lead bromide lattice that function as radiative centres. This finding will benefit the design of perovskite systems for efficient red emission.
ABSTRACT
Fluorosis causes female reproductive dysfunction with reduced fertility without established pathogenesis. To clarify the mechanism, Sprague-Dawley female rats were selected with drinking water containing 0, 50 (low), 100 (moderate), and 150 mg/L (high) sodium fluoride (NaF) for a short (2 months), medium (4 months), and long term (6 months). The water consumption and body weight of female rats were recorded daily. The effect of NaF on the estrous cycle was examined by vaginal smears and recorded in different term treatments. Female and male rats were mated in a 2:1 ratio for 1 week at 2-, 4-, and 6-month treatment time for mating performance and fertility rate. Selected female rats were executed for tissue and blood collection at different treatment terms. Twenty-four-hour urine sample from each female rat was collected using the metabolic cage. The levels of steroid hormones and silent information regulator 2 homolog 1 (SIRT1) in serum were measured by appropriate ELISA kits. Body weight of the high NaF group was significantly less during short-term treatment than that of other treatment groups or control group. Urinary fluoride concentration was increased linearly with treatment time. Treatment of NaF significantly decreased steroid hormone level while increased SIRT1 level in the serum. In addition, NaF treatment significantly decreased pregnancy rate. It is concluded that NaF inhibits the secretion of hormone and estradiol (E2) release from the ovary, thereby reducing the rate of pregnant. SIRT1 may be involved in this NaF-induced reproductive dysfunction in female rats through regulating reproductive hormone, FSH, and LH secretion.
Subject(s)
Sirtuin 1 , Sodium Fluoride , Pregnancy , Rats , Female , Male , Animals , Sodium Fluoride/pharmacology , Rats, Sprague-Dawley , Estradiol , Fluorides , Body WeightABSTRACT
Two-dimensional (2D) Dion-Jacobson (DJ) perovskites are drawing significant attention in optoelectronic fields because of their enhanced out-of-plane electron coupling and improved structure stability. However, the structural effects of organic cations on the in-plane charge transport properties of 2D DJ lead bromide perovskites have remained less explored. Herein, we adopt asymmetric 3-(dimethylamino)-1-propylammonium (DMPD) and symmetric butane-1,4-diammonium (BDA) to systematically investigate the influence of organic cations on the structural, optical, and in-plane charge transport properties of 2D lead bromide perovskites. The large penetration depth of DMPD2+ induces a decreased perovskite layer distortion and a lower bandgap in DMPDPbBr4, compared with that of BDAPbBr4. Moreover, DMPDPbBr4 is shown to possess a low exciton binding energy, a low defect density, and a low ion migration activation energy, thereby yielding a more efficient in-plane charge collection efficiency than BDAPbBr4. Density functional theory calculations suggest that the improved in-plane charge transport can be traced to the enlarged antibonding coupling between Pb-6s and Br-4p orbitals that enables a high band dispersion and a low carrier effective mass in the in-plane direction of DMPDPbBr4. Finally, the planar Ag/DMPDPbBr4/Ag photodetector delivers a satisfying detectivity of 1.73 × 1012 Jones under an incident power intensity of 0.16 mW cm-2 and a high on/off ratio of 5.3 × 103. The above findings offer novel insight for the design of 2D DJ lead bromide perovskites for optoelectronic devices.
ABSTRACT
Fluorosis often causes female reproductive dysfunction. A rapid turnover of DNA methylation is a pathological change in many human diseases, including female reproductive dysfunction. The role of DNA methylation in fluorosis was unknown and investigated in this experiment. Fifty fluorosis women patients were selected as High F group and forty-six healthy women were recruited as Control group were enrolled. In addition, ovarian granulosa cells were obtained from five women in High F group and five women in Control group. All ten women went through in vitro fertilization (IVF) process with DNA methylation sequencing. KGN cells (human granulosa cell line) were cultured with different concentrations of sodium fluoride (0-8 mM NaF) for 24 h for the in vitro study. The level of DNA methylation in blood samples was significantly higher in High F group than that in Control group. The level of serum estradiol (E2) was significantly lower in women from High F group, while the levels of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in High F group were significantly higher than that in Control group. The methylation sequences of KGN cells relating to autophagy were significantly changed by NaF treatment dose-dependently. Based on these results, it is concluded that DNA methylation and autophagy may play a significant role in the pathophysiology of reproductive dysfunction caused by fluorosis.
