High defect tolerance ß-CsSnI3 perovskite light-emitting diodes.

All-inorganic lead-free CsSnI3 has shown promising potential in optoelectronic applications, particularly in near-infrared perovskite light-emitting diodes (Pero-LEDs). However, non-radiative recombination induced by defects hinders the optoelectronic properties of CsSnI3-based Pero-LEDs, limiting their potential applications. Here, we uncovered that ß-CsSnI3 exhibits higher defect tolerance compared to orthorhombic γ-CsSnI3, offering a potential for enhancing the emission efficiency. We further reported on the deposition and stabilization of highly crystalline ß-CsSnI3 films with the assistance of cesium formate to suppress electron-phonon scattering and reduce nonradiative recombination. This leads to an enhanced photoluminescence quantum yield up to ∼10%. As a result, near-infrared LEDs based on ß-CsSnI3 emitters are achieved with a peak external quantum efficiency of 1.81% and excellent stability under a high current injection of 1.0 A cm-2.

Determining the vertebra for pedicle subtraction osteotomy in surgical correction for ankylosing spondylitis with thoracolumbar kyphosis.

OBJECTIVE: This study aimed to provide a method for determining the apical vertebra for pedicle subtraction osteotomy (PSO) in corrective surgery for patients with ankylosing spondylitis (AS) with thoracolumbar kyphosis (TLK). METHODS: The medical records of AS patients with TLK who underwent PSO between May 2009 and August 2022 were retrospectively reviewed, and 235 patients were included in the study. Using the proposed method, choosing the vertebra based on Kim's apex (KA), which is defined as the farthest vertebra from a line drawn from the center of the T10 vertebral body to the midpoint of the S1 upper endplate, the authors analyzed 229 patients with apices at T12, L1, or L2 (excluding L3 because of the small sample size, n = 6). They divided all patients into two groups. Group A (n = 144) underwent PSO at the KA vertebra, while group B (n = 85) underwent PSO at a different level. Demographic and radiological data, including sagittal spinopelvic parameters of the entire spine, were collected. An additional analysis was performed on patients with the same KA vertebra. RESULTS: The vertebra distributions of patients based on KA were T12 (28 [12.2%]), L1 (119 [52.0%]), and L2 (82 [35.8%]). The corrections of sagittal vertical axis (SVA; 101.0 ± 48.5 mm vs 82.0 ± 53.8 mm, p = 0.010), global kyphosis (GK; 31.6° ± 10.0° vs 26.4° ± 10.5°, p = 0.005), and TLK (29.4° ± 10.2° vs 24.2° ± 12.9°, p = 0.012) in group A were significantly greater than those in group B, and there was no difference in the corrections of thoracic kyphosis (TK), lumbar lordosis, and pelvic incidence between the two groups. On further analysis, group A showed greater correction in TK (26.2° ± 13.7° vs 0.1° ± 8.1°, p = 0.013) for patients with T12 as the KA; greater improvements in SVA (101.5 ± 44.2 mm vs 73.4 ± 48.7 mm, p = 0.020), GK (30.6° ± 11.0° vs 25.0° ± 10.4°, p = 0.046), and TLK (32.6° ± 7.8° vs 26.7° ± 9.9°, p = 0.012) for those with L1 as the KA; and significant correction in TLK (30.0° ± 6.3° vs 4.3° ± 19.5°, p = 0.008) for patients with L2 as the KA, compared with group B. CONCLUSIONS: PSO at the apical vertebra provides a greater degree of correction of sagittal imbalance. The proposed method, selecting the vertebra based on KA, is easily reproducible for determining the apex level in AS patients with TLK.

Enhanced Energy Storage in PVDF-Based Nanocomposite Capacitors through (00l)-Oriented BaTiO3 Single-Crystal Platelets.

Flexible nanocomposite dielectrics with inorganic nanofillers exhibit great potential for energy storage devices in advanced microelectronics applications. However, high loading of inorganic nanofillers in the matrix results in an inhomogeneous electric field distribution, thereby hindering the improvement of the energy storage density (Ue) of the dielectrics. Herein, we proposed a strategy that utilized (00l)-oriented barium titanate (BT) single-crystal platelets to fabricate trilayered nanocomposite dielectrics for energy storage applications. The trilayered nanocomposites consisted of two high-permittivity layers of (Ta2O5, Al2O3) codoped TiO2 nanoparticles (Ta-Al@TiO2 nps) dispersed in a poly(vinylidene fluoride) (PVDF) matrix to facilitate large electric displacement and a middle layer of (00l)-oriented BT single-crystal platelets to provide high breakdown strength. Hence, the trilayered PVDF/Ta-Al@TiO2 nps/BT single-crystal platelet nanocomposite film attains an outstanding Ue of 16.9 J cm-3 at 370 kV mm-1, which is ∼625% higher than that of the single-layer PVDF/Ta-Al@TiO2 nps film. Finite element simulation further clarified that the successive inner layer of highly (00l)-oriented BT single-crystal platelets could effectively restrain the propagation of electrical treeing in trilayered nanocomposites. This research offers an effective approach for developing flexible dielectric capacitors with an excellent energy storage performance.

Regulating The Electronic Configuration of Low-Dimensional Hybrid Perovskites via Organic Cations for Self-Powered Ultraviolet Photodetectors.

Ultraviolet photodetectors (UPDs) based on low-dimensional halide perovskites have undergone rapid development. Here, regulation of the electronic configuration of low-dimensional hybrid perovskites are reported via organic cations for self-powered UPDs. For the first time, it is determine that the rational design of organic cation phenyl alkylammonium can effectively prevent phonon scattering thus increasing charge carrier extraction in low dimensional lead chlorine perovskite thin-films. As a result, the exciton-binding energy can be reduced to 62.91 meV in (PMA)2 PbCl4 perovskite films with a charge-carrier mobility of 0.335 cm2  V-1  s-1 . The fabricated (PMA)2 PbCl4 -based self-powered UPDs has achieved a high detectivity of 6.32 × 1013 jones with a low noise current of 0.35 pA Hz-1/2 under zero bias. A further demonstration of images with high UV to visible light rejection ratio under weak-light illumination of 70 nW cm-2 highlights the feasible potential application of low-dimensional perovskite.

Characteristics and standards of severe sagittal imbalance in adult patients with spinal deformities: a retrospective analysis.

OBJECTIVE: To analyze the characteristics of "severe" dynamic sagittal imbalance (DSI) in patients with adult spinal deformity (ASD) and establish criteria for them. METHODS: We retrospectively analyzed 102 patients with ASD presenting four cardinal signs of lumbar degenerative kyphosis. All patients underwent deformity corrective surgery and were divided into three groups according to the diagnostic criteria based on the Oswestry disability index and dynamic features (△Timewalk: time until C7 sagittal vertical axis [C7SVA] reaches ≥ 20 cm after the start of walking) of sagittal imbalance. The paravertebral back muscles were analyzed and compared using T2-weighted axial imaging. We performed a statistically time-dependent spinopelvic sagittal parameter analysis of full standing lateral lumbar radiographs. Lumbar flexibility was analyzed using dynamic lateral lumbar radiography. RESULTS: The patients were classified into the mild (△Timewalk ≥ 180 s, 35 patients), moderate (180 s > △Timewalk ≥ 30 s, 38 patients), and severe (△Timewalk < 30 s, 29 patients) groups. The back muscles in the severe group exhibited a significantly higher signal intensity (533.4 ± 237.5, p < 0.05) and larger area of fat infiltration (35.2 ± 5.4, p < 0.05) than those in the mild (223.8 ± 67.6/22.9 ± 11.9) and moderate groups (294.4 ± 214.7/21.6 ± 10.6). The analysis of lumbar flexibility revealed significantly lower values in the severe group (5.8° ± 2.5°, p < 0.05) than in the mild and moderate groups (14.2° ± 12.4° and 11.4° ± 8.7°, respectively). The severe group had significantly lower lumbar lordosis (LL, 25.1° ± 22.7°, p < 0.05) and Pelvic incidence-LL mismatch (PI-LL, 81.5° ± 26.6°, p < 0.001) than those of the mild (8.2° ± 16.3°/58.7° ± 18.8°) and moderate (14.3° ± 28.6°/66.8° ± 13.4°) groups. On receiver operating characteristic curve analysis, PI-LL was statistically significant, with an area under the curve of 0.810 (95% confidence interval) when the baseline was set at 75.3°. The severe group had more postoperative complications than the other groups. CONCLUSIONS: Our results suggest the following criteria for severe DSI: C7SVA > 20 cm within 30 s of walking or standing, a rigid lumbar curve < 10° on dynamic lateral radiographs, and a PI-LL mismatch > 75.3°.

Progress and Challenges Toward Effective Flexible Perovskite Solar Cells.

The demand for building-integrated photovoltaics and portable energy systems based on flexible photovoltaic technology such as perovskite embedded with exceptional flexibility and a superior power-to-mass ratio is enormous. The photoactive layer, i.e., the perovskite thin film, as a critical component of flexible perovskite solar cells (F-PSCs), still faces long-term stability issues when deformation occurs due to encountering temperature changes that also affect intrinsic rigidity. This literature investigation summarizes the main factors responsible for the rapid destruction of F-PSCs. We focus on long-term mechanical stability of F-PSCs together with the recent research protocols for improving this performance. Furthermore, we specify the progress in F-PSCs concerning precise design strategies of the functional layer to enhance the flexural endurance of perovskite films, such as internal stress engineering, grain boundary modification, self-healing strategy, and crystallization regulation. The existing challenges of oxygen-moisture stability and advanced encapsulation technologies of F-PSCs are also discussed. As concluding remarks, we propose our viewpoints on the large-scale commercial application of F-PSCs.

Single-Crystal Nanowire Cesium Tin Triiodide Perovskite Solar Cell.

This work reports for the first time a highly efficient single-crystal cesium tin triiodide (CsSnI3 ) perovskite nanowire solar cell. With a perfect lattice structure, low carrier trap density (≈5 × 1010 cm-3 ), long carrier lifetime (46.7 ns), and excellent carrier mobility (>600 cm2 V-1 s-1 ), single-crystal CsSnI3 perovskite nanowires enable a very attractive feature for flexible perovskite photovoltaics to power active micro-scale electronic devices. Using CsSnI3 single-crystal nanowire in conjunction with highly conductive wide bandgap semiconductors as front-surface-field layers, an unprecedented efficiency of 11.7% under AM 1.5G illumination is achieved. This work demonstrates the feasibility of all-inorganic tin-based perovskite solar cells via crystallinity and device-structure improvement for the high-performance, and thus paves the way for the energy supply to flexible wearable devices in the future.

Achieving High Responsivity and Detectivity in a Quantum-Dot-in-Perovskite Photodetector.

This work reports on quantum dots (QDs) in perovskite photodetectors showing high optoelectronic performance via quantum-dot-assisted charge transmission. The self-powered broad-band photodetector constructed with SnS QDs in FAPb0.5Sn0.5I3 perovskite can capture incoming optical signals directly at zero bias. The QDs-in-perovskite photodetector exhibits a high sensitivity in the wavelength range from 300 to 1000 nm. Its responsivity at 850 nm reaches 521.7 mA W-1, and a high specific detectivity of 2.57 × 1012 jones can be achieved, which is well beyond the level of previous self-powered broad-band photodetectors. The capability of quantum-dot-in-perovskite photodetectors as data receivers has been further demonstrated in a visible-light communication application.

Surgical sequence in anterior column realignment with posterior osteotomy is important for degree of adult spinal deformity correction: advantages and indications for posterior to anterior sequence.

BACKGROUND: We hypothesized that posterior osteotomy prior to ACR (Anterior column realignment) through P-A-P surgical sequence would permit a greater correction for deformity corrective surgery than the traditional A-P sequence without posterior osteotomy. This study aimed to determine the impact of the P-A-P sequence on the restoration of lumbar lordosis (LL) compared to the A-P sequence in deformity corrective surgery for adult spinal deformity (ASD) patients and to identify the characteristics of patients who require this sequence.  METHODS: Between 2017 and 2019, 260 ASD patients who had undergone combined corrective surgery were reviewed retrospectively. This study included 178 patients who underwent posterior osteotomy before the ACR (P-A group) and 82 patients who underwent the A-P sequence (A-P group). Sagittal spinopelvic parameters were determined from pre- and postoperative whole-spine radiographs and compared between the groups. To find better indications for the P-A-P sequence, we conducted additional analysis on postoperative outcomes of patients in the A-P group.  RESULTS: The P-A group showed a significantly higher change in LL (53.7° vs. 44.3°, p < 0.001), C7 sagittal vertical axis (C7 SVA: 197.4 mm vs. 146.1 mm, p = 0.021), segmental lordosis (SL) L2/3 (16.2° vs. 14.4°, p = 0.043), SL L3/4 (16.2° vs. 13.8°, p = 0.004), and SL L4/5 (15.1° vs. 11.3°, p = 0.001) compared to the A-P group. At the final follow-up, pelvic incidence (PI) minus LL mismatch (PI - LL mismatch) was significantly higher in the A-P group (13.4° vs. 2.9°, p < 0.001). Stepwise logistic regression analysis showed that age ≥ 75 years (odds ratio [OR] = 2.151; 95% confidence interval [CI], 1.414-3.272; p < 0.001), severe osteoporosis (OR = 2.824; 95% CI, 1.481-5.381; p = 0.002), rigid lumbar curve with dynamic changes in LL < 10° (OR = 5.150; 95% CI, 2.296-11.548; p < 0.001), and severe facet joint osteoarthritis (OR = 4.513; 95% CI, 1.958-10.402; p < 0.001) were independent risk factors for PI - LL mismatch ≥ 10° after A-P surgery. CONCLUSION: P-A-P sequence for deformity corrective surgery in ASD offers greater LL correction than the A-P sequence. Indications for the procedure include patients aged ≥ 75 years, severe osteoporosis, rigid lumbar curve with dynamic change in LL < 10°, or more than four facet joints of Pathria grade 3 in the lumbar region.

Significantly Enhanced Energy Storage Performance of Lead-Free BiFeO3-Based Ceramics via Synergic Optimization Strategy.

Owing to the merits of giant power density and ultrafast charge-discharge time, dielectric capacitors including ceramics and films have inspired increasing interest lately. Nevertheless, the energy storage density of dielectric ceramics should be further optimized to cater to the boosting demand for the compact and portable electronic devices. Herein, an ultrahigh recoverable energy storage density Wrec of 13.44 J/cm3 and a high efficiency η of 90.14% are simultaneously realized in BiFeO3-BaTiO3-NaTaO3 relaxor ferroelectric ceramics with high polarization Pmax, reduced remanent polarization Pr, and optimized electric breakdown strength Eb. High Pmax originates from the genes of BiFeO3-based ceramics, and reduced Pr is induced by enhanced relaxor behavior. Particularly, a large Eb is achieved by the synergic contributions from complicated internal and external factors, such as decreased grain size and improved resistivity and electrical homogeneity. Furthermore, the ceramics also exhibit satisfactory frequency, cycling and thermal reliability, and decent charge-discharge property. This work not only indicates that the BiFeO3-based relaxor ferroelectric materials are promising choices for the next-generation electrostatic capacitors but also paves a potential approach to exploit novel high-performance dielectric ceramics.

Ultrahigh Energy Storage Density and High Efficiency in Lead-Free (Bi0.9Na0.1)(Fe0.8Ti0.2)O3-Modified NaNbO3 Ceramics via Stabilizing the Antiferroelectric Phase and Enhancing Relaxor Behavior.

Dielectric capacitors have attracted growing attention because of their important applications in advanced high power and/or pulsed power electronic devices. Nevertheless, the synergistic enhancement of recoverable energy storage density (Wrec > 10 J/cm3) and efficiency (η > 80%) is still a great challenge for lead-free dielectric bulk ceramics. Herein, by introducing complex perovskite compound (Bi0.9Na0.1)(Fe0.8Ti0.2)O3 with a smaller tolerance factor into an NaNbO3 matrix (NN-BNFT), we have achieved and explored stable relaxor antiferroelectric ceramics with enhanced relaxor behavior. Of particular importance is the composition of 0.88NN-0.12BNFT, which exhibits a large electric breakdown strength Eb of 87.3 kV/mm, an ultrahigh Wrec of 12.7 J/cm3, and a high efficiency η of 82.5%, as well as excellent thermal reliability and an ultrafast discharge speed, resulting from the dense microstructure, the moderate dielectric constant, the reduced grain size, the dielectric loss, and the sample thickness. The outstanding energy storage properties of NN-BNFT display great promise in advanced dielectric capacitors for energy storage applications.

Enhanced energy storage density of all-organic fluoropolymer composite dielectric via introducing crosslinked structure.

Polymer-based dielectrics have been attracted much attention to flexible energy storage devices due to their rapid charge-discharge rate, flexibility, lightness and compactness. Nevertheless, the energy storage performance of these dielectric polymers was limited by the weak dielectric breakdown properties. Crosslinked structure has been proven efficient to enhance breakdown strength (E b) and charge-discharge efficiency (η) of polymer film capacitors. However, crosslinked networks usually lead to low electric displacement of dielectric capacitors, which greatly restrict their energy storage density (U d). In this work, we present a tri-layered composite via layer-by-layer casting technology, where crosslinked polyvinylidene fluoride (c-PVDF) was used as the inter-layer to offer high breakdown strength, and the outer ternary fluoropolymer layers with high dielectric constant could provide high electric displacement. The optimal tri-layered composites exhibit an ultrahigh discharge energy density of 18.3 J cm-3 and a discharge efficiency of 60.6% at 550 kV mm-1. This energy density is much higher than that of the PVDF terpolymer and commercially biaxially oriented polypropylene (BOPP, 1-2 J cm-3). The simulation results prove that the enhanced energy density originates from the effectively depressed charge transport in crosslinked structure at high applied electric field. Moreover, this work provides a feasible method for developing flexible all-organic high-energy-density composites for polymer capacitors.

High efficiency frequency upconversion of photons carrying orbital angular momentum for a quantum information interface.

The orbital angular momentum (OAM) of light shows great potential in quantum communication. The transmission wavelength for telecom is usually around 1550 nm, while the common quantum information storage and processing devices based on atoms, ions or NV color centers are for photons in visible regime. Here we demonstrate a quantum information interface based on the frequency upconversion for photons carrying OAM states from telecom wavelength to visible regime by sum-frequency generation with high quantum conversion efficiency. The infrared photons at 1558 nm carrying different OAM values were converted to the visible regime of 622.2 nm, and the OAM value of the signal photons was well preserved in the frequency upconversion process with pump beam in Gaussian profile.