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The contact behavior of a stepseal affects its reliability and remaining life. In this study, experimental and numerical analyses were performed to investigate the contact behavior of a typical stepseal. Its dimensions and material properties were also tested. The Mooney–Rivlin hyperelastic model was used to fit the stress–strain data of the rubber. A static contact pressure of 105.1 MPa was obtained using the Fujifilm pressure measurement film. A finite element model of a stepseal with reasonable element sizes was established. A comparison between the experimental results and finite element (FE) predictions shows that the finite element method underpredicts the maximum static contact pressure and contact length. For the maximum contact pressure, the test results were approximately 30.4% higher than those of the FE predictions. [ABSTRACT FROM AUTHOR]

Realization of remote wearable health monitoring (RWHM) technology for the flexible photodiodes is highly desirable in remote‐sensing healthcare systems used in space stations, oceans, and forecasting warning, which demands high external quantum efficiency (EQE) and detectivity in NIR region. Traditional inorganic photodetectors (PDs) are mechanically rigid and expensive while the widely reported solution‐processed mixed tin‐lead (MSP) perovskite photodetectors (PPDs) exhibit a trade‐off between EQE and detectivity in the NIR region. Herein, a novel functional passivating antioxidant (FPA) strategy has been introduced for the first time to simultaneously improve crystallization, restrain Sn2+ oxidization, and reduce defects in MSP perovskite films by multiple interactions between thiophene‐2‐carbohydrazide (TAH) molecules and cations/anions in MSP perovskite. The resultant solution‐processed rigid mixed Sn–Pb PPD simultaneously achieves high EQE (75.4% at 840 nm), detectivity (1.8 × 1012 Jones at 840 nm), ultrafast response time (trise/tfall = 94 ns/97 ns), and improved stability. This work also highlights the demonstration of the first flexible photodiode using MSP perovskite and FPA strategy with remarkably high EQE (75% at 840 nm), and operational stability. Most importantly, the RWHM is implemented for the first time in the PIN MSP perovskite photodiodes to remotely monitor the heart rate of humans at rest and after‐run conditions. [ABSTRACT FROM AUTHOR]

Recently, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has been developed to exceed 25%, and charge transport layer optimization is a promising strategy for further efficiency improvement in PSCs. Herein, a supramolecular complex [(C8H17)4N]4[SiW12O40] (TASiW‐12) is synthesized and its doped form in SnO2 (hereafter S‐SnO2) is used as a charge transport layer (electron transport layer, ETL). This study demonstrates that S‐SnO2 introduction is a practical and effective way to improve the bulk ETL and those of the ETL/perovskite interface. S‐SnO2 leads to improved band alignment, suppressed trap‐assisted charge recombination, and enhanced electron mobility. In addition, an enhanced open‐circuit voltage (Voc) of 1.16 V and an efficiency of 22.8% are successfully achieved in n–i–p planar PSCs. Meanwhile, S‐SnO2 acts as a crucial agent to reduce charge accumulation at the S‐SnO2/perovskite interface. The device possesses superior stability for 3072 h with only a 5.65% loss of the initial PCE. These results indicate that high‐efficiency PSCs can be easily attained by introducing a TASiW‐12‐doped ETL with integrated functions. [ABSTRACT FROM AUTHOR]

The efficient electron transfer at the interface of the electron transport layer (ETL) and perovskite, and the transportation along the ETL and collection at the electrode are characteristics that are critically governed by the properties of the ETL. Both characteristics are fundamental for the fabrication of high-performance perovskite solar cells (PSC). So far, mesoporous TiO2 might be considered a versatile ETL as its structure can provide an enormous heterojunction with the perovskite absorber. However, its inert (101) pore facet, massive dead-end pore structure, and extensive grain boundary with the underlying layers in the PSC device have made them unlikely to meet those basic criteria. Here, we have come up with a new design of TiO2 ETL that provides a high carrier dynamic in the device. It is a 3 nm thick high-energy (001) faceted single-crystalline nanograss-like structure (TNG) that is vertically grown on the ITO surface. With these unique structural properties, we achieved an enhanced carrier extraction from the perovskite layer, transportation along the ETL and collection at the electrode. Our results indicate that the charge-transfer dynamic at the TNG–perovskite interface and transport in the device are up to more than 2 times faster than those in the control device or in the recently reported results. With this property, we recorded a power conversion efficiency (PCE) as high as 21.60% (or at the level of 20.84% on average) from the TNG-based PSC with the device area as high as ∼0.17 cm2 using triple cation Cs0.05[MA0.13FA0.87]0.95Pb(I0.87Br0.13)3 perovskites, an improvement as high as 18% from the control device. The TNG with its unique structure and surface chemistry may become a potential platform for the fabrication of a high-performance PSC device via combination with a high-performance perovskite system. [ABSTRACT FROM AUTHOR]

Toward pursuing high‐performance photodetectors based on 2D transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS2), it is desirable to reduce the high dark current and sluggish response time. Here, in multilayer MoS2‐based photodetectors, a 2D halide perovskite, (C6H5C2H4NH3)2PbI4 ((PEA)2PbI4), is introduced as a bifunctional material: both as electron reservoir to reduce free carriers and passivation agent to passivate defects. Surprisingly, dark current is suppressed by six orders of magnitude after coating a (PEA)2PbI4 thin layer onto pristine MoS2 photodetector, with the dark current decreased to 10−11 A. This huge reduction of dark current suggests an efficient interlayer charge transfer from MoS2 to (PEA)2PbI4, which is further verified by photoluminescence quenching phenomenon. It indicates that (PEA)2PbI4 serves as electron reservoir to reduce carrier density of MoS2, resulting in ultrahigh detectivity (1.06 × 1013 Jones). Moreover, the response speed is also accelerated by more than 100‐fold due to passivation by 2D perovskite. In addition, it is found that this type of photodetectors can further work at self‐power mode (with the bias of 0 V). Therefore, the strategy of applying 2D perovskite on the surface of TMDs provides a novel way to fabricate high‐performance photodetectors. [ABSTRACT FROM AUTHOR]

Optoelectronic synaptic transistors are attractive for applications in next-generation brain-like computation systems, especially for their visible-light operation and in-sensor computing capabilities. However, from a material perspective, it is difficult to build a device that meets expectations in terms of both its functions and power consumption, prompting the call for greater innovation in materials and device construction. In this study, we innovatively combined a novel perovskite carrier supply layer with an Al/MoO 3 interface carrier regulatory layer to fabricate optoelectronic synaptic devices, namely Al/MoO 3 /CsFAMA/ITO transistors. The device could mimic a variety of biological synaptic functions and required ultralow-power consumption during operation with an ultrafast speed of >0.1 μs under an optical stimulus of about 3 fJ, which is equivalent to biological synapses. Moreover, Pavlovian conditioning and visual perception tasks could be implemented using the spike-number-dependent plasticity (SNDP) and spike-rate-dependent plasticity (SRDP). This study suggests that the proposed CsFAMA synapse with an Al/MoO 3 interface has the potential for ultralow-power neuromorphic information processing., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Perovskite single-crystal redissolution (PSCR) strategy is highly desired for efficient formamidinium lead triiodide (FAPbI 3 ) perovskite photovoltaics with enhanced phase purity, improved film quality, low trap-state density, and good stability. However, the phase transition and crystallization dynamics of FAPbI 3 remain unclear in the PSCR process compared to the conventional fabrication from the mixing of precursor materials. In this work, a green-solvent-assisted (GSA) method is employed to synthesize centimeter-sized α-FAPbI 3 single crystals, which serve as the high-purity precursor to fabricate perovskite films. The α-FAPbI 3 PSCR strategy facilitates direct α-phase formation and inhibits the complex intermediate phases monitored by in situ grazing-incidence wide-angle X-ray scattering. Moreover, the α-phase stability is prolonged due to the relaxation of the residual lattice strain through the isotropic orientation phase growth. Consequently, the GSA-assisted PSCR strategy effectively promotes crystallization and suppresses non-radiative recombination in perovskite solar cells, which boosts the device efficiency from 22.08% to 23.92% with significantly enhanced open circuit voltage. These findings provide deeper insight into the PSCR process in terms of its efficacy in phase formation and lattice strain release. The green low-cost solvent may also offer a new and ideal solvent candidate for large-scale production of perovskite photovoltaics., (© 2023 Wiley-VCH GmbH.)

A deficiency in the photoelectrical dynamics at the interface due to the surface traps of the TiO 2 electron transport layer (ETL) has been the critical factor for the inferiority of the power conversion efficiency (PCE) in the perovskite solar cells. Despite its excellent energy level alignment with most perovskite materials, its large density of surface defect as a result of sub lattice vacancies has been the critical hurdle for an efficient photovoltaic process in the device. Here, we report that atoms thick 2D TiS 2 layer grown on the surface of a (001) faceted and single-crystalline TiO 2 nanograss (NG) ETL have effectively passivated the defects, boosting the charge extractability, carrier mobility, external quantum efficiency, and the device stability. These properties allow the perovskite solar cells (PSCs) to produce a PCE as high as 18.73% with short-circuit current density ( J sc ), open-circuit voltage ( V oc ), and fill-factor (FF) values as high as 22.04 mA/cm 2 , 1.13 V, and 0.752, respectively, a 3.3% improvement from the pristine TiO 2 -NG-based PSCs. The present approach should find an extensive application for controlling the photoelectrical dynamic deficiency in perovskite solar cells.