Search

Real‐time recognition of non‐driving behaviors is of great importance in conditionally automated driving, as it determines the takeover time budget, which in turn has a huge impact on the performance of the takeover. Here, a novel real‐time non‐driving behavior recognition system (RNBRS) integrating self‐powered, low‐cost, easy‐to‐manufacture triboelectric sensors, and a deep learning model is proposed. The structure, working mechanism, and electrical characteristics of triboelectric sensors are investigated and analyzed. Through the ingenious structural design of single‐electrode triboelectric sensors and driving simulation experiments under conditional automated driving, non‐driving behaviors are captured in the form of electrical signals. A well‐trained long short‐term memory network model is adopted to recognize the five most typical non‐driving behaviors, including phone, console touchpad, driving, monitoring driving, and no operation, and test accuracy of 93.5% is achieved. Demonstration of a set of controlled experiments shows that RNBRS enables vehicles with conditional automation to dynamically adjust takeover time budget based on driver behavior, therefore significantly improving both safety and stability of takeover. This study opens new frontiers for the development of self‐powered electronics and inspires new thoughts on human‐machine interaction and the safety of autonomous vehicles. [ABSTRACT FROM AUTHOR]

Control and design of reaction conditions to acquire desirable morphology is a complex and difficult process. In principle, one can always predict the equilibrium morphologies of nanoparticles once the specific surface energies of exposed crystallographic facets become available. However, the surface energies can be easily changed by environmental conditions, and are rarely measured. As a result, we employ the k-nearest neighbors (KNN) model to predict surface energies from experimentally observed equilibrium morphologies of rutile TiO2, which may provide guidelines for the rational design and synthesis of rutile TiO2 micro-/nanocrystals with desired morphologies. [ABSTRACT FROM AUTHOR]

SnO2‐based planar perovskite solar cells (PSCs) have attracted extensive attention owing to their simple structure and low‐temperature processing. However, the imperfect interface contact caused by surface defects and energy‐level mismatches greatly hinder the further improvement of the efficiency and stability of PSC. Herein, a multifunctional interfacial crosslinking agent D‐penicillamine (DPM) is introduced to improve the interface contact between SnO2 and upper perovskite. Through systematical analysis, it is found that the DPM used to modify SnO2 can simultaneously passivate the defects on the surface of SnO2 via esterification reaction, promote the charge extraction in perovskite by adjusting the interface energy‐level arrangement, and improve the quality of perovskite film by forming coordination bond with lead ions. These merits eventually assist DPM‐modified PSCs and achieve an impressive efficiency of 24.09%, whereas the controlled device only shows an efficiency of 22.44%. In addition, an unencapsulated DPM‐modified PSC exhibits better storage stability, thermal stability, and light stability than the controlled device, as well as in situ absorption capacity of leaked lead ions. [ABSTRACT FROM AUTHOR]

Expeditious charge transfer at the interfaces between photoactive and charge transport layers is critical in perovskite solar cells (PSCs). Defects on the surface of charge transport layers usually lead to the degradation of carrier mobility, resulting in low power conversion efficiency (PCE) and serious hysteresis. Herein, phosphorus‐containing Lewis acids are applied to modify the SnO2/perovskite interface and neutralize redundant OH− on the SnO2 surface. The interaction between the Lewis acids and SnO2 significantly accelerate the electron transfer and greatly reduce the energy barrier at the SnO2/perovskite interface, boosting the PCE of the PSCs. By modifying the SnO2/pervoskite interface with diphenylphosphine oxide, the PCE of a small area device was increased from 18.94% to 22.14%, along with negligible hysteresis and improved stability. Moreover, the 5 × 5 cm2 solar modules with an aperture area of 22.56 cm2 achieved a best efficiency of 15.69%. [ABSTRACT FROM AUTHOR]

The contact electrification of ferroelectric polymer can be more complicated due to its ordered permanent molecular dipoles and dipole–dipole interactions. Herein, the polyvinylidene fluoride (PVDF)‐Cu is taken as an example to investigate the mechanism of ferroelectric polymer‐metal contact electrification via first‐principles calculations. It is revealed that different from non‐ferroelectric polymers, when ferroelectric polymers are in contact with metals, the charge transfer occurs not only at the interface but also inside the polymer due to the existence of polar phases. Specifically, the polar phases in the crystallization region can effectively enhance the charge transfer between the ferroelectric polymer and metal because the polar molecules in PVDF possess the stronger electrostatic potential, more delocalized lowest unoccupied molecular orbital, and additional dipole–dipole interactions compared with nonpolar molecules. In addition, the coupling mechanism of piezoelectricity and triboelectricity in ferroelectric polymer‐metal contact electrification under compression is also investigated. It is demonstrated that the deformation increases the degree of noncoincidence between positive and negative charge centers in polar phases and causes charge transfer between the polar molecular chains of PVDF, thus producing the extra charge transfer between the ferroelectric polymer and metal. This study provides a theoretical basis for the material design of triboelectric nanogenerators based on ferroelectric polymers. [ABSTRACT FROM AUTHOR]

With the continuous improvement of performance of lead‐based perovskite solar cells (PSCs), the potential harm of water‐soluble lead ion (Pb2+) to environment and public health is emerging as a major obstacle to their commercialization. Herein, an amphoteric phenylbenzimidazole sulfonic acid (PBSA) that is almost insoluble in water is added to the perovskite precursor to simultaneously regulate crystallization growth, passivate defects, and mitigate lead leakage of high‐performance PSCs. Through systematic research, it is found that PBSA can not only regulate the crystallization of perovskite grains to form the film, but also passivate the defects of annealed films mainly due to the strong interaction between the functional groups in PBSA and Pb2+, which greatly improves the crystallinity and stability of perovskite films. Consequently, the highest power conversion efficiency of 23.27% is achieved in 0.09 cm2 devices and 15.31% is obtained for large‐area modules with an aperture area of 19.32 cm2, along with negligible hysteresis and improved stability. Moreover, the leakage of lead ions from unpackaged devices is effectively prevented owing to the strong coupling between PBSA molecules and water‐soluble Pb2+ to form insoluble complexes in water, which is of great significance to promote the application of optoelectronic devices based on lead‐based perovskite materials. [ABSTRACT FROM AUTHOR]

In addition to high efficiencies, upscaling and long‐term operational stability are key pre‐requisites for moving perovskite solar cells toward commercial applications. In this work, a strategy to fabricate large‐area uniform and dense perovskite films with a thickness over one‐micrometer via a two‐step coating process by introducing NH4Cl as an additive in the PbI2 precursor solution is developed. Incorporation of NH4Cl induces the formation of the intermediate phases of x[NH4+]·[PbI2Clx]x− and HPbI3−xClx, which can effectively retard the crystallization rate of perovskite leading to uniform and compact full‐coverage perovskite layers across large areas with high crystallinity, large grain sizes, and small surface roughness. The 5 × 5 and 10 × 10 cm2 perovskite solar modules (PSMs) based on this method achieve a power conversion efficiency (PCE) of 14.55% and 10.25%, respectively. These PSMs also exhibit good operational stability with a T80 lifetime (the time during which the solar module PCE drops to 80% of its initial value) under continuous light illumination exceeding 1600 h (5 × 5 cm2) and 1100 h (10 × 10 cm2), respectively. [ABSTRACT FROM AUTHOR]

A novel cellulose/TiO2/β-CD hydrogel with high photocatalytic antibacterial activity and sustained release of drug was prepared. TiO2 sol with a diameter of about 9 nm in this hydrogel was the photoantibacterial agent. β-CD can significantly enhance photoantibacterial activity and the sustained-release effect of this hydrogel. The structure and property of this hydrogel composite were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Escherichia coli and Staphylococcus aureus were selected as model bacteria to evaluate the antibacterial activity of the composite hydrogel under natural light irradiation and darkness, respectively. The in vitro release experiment used curcumin as a model drug in PBS buffer solution. The influence of β-CD on the antibacterial activity and sustained-release effect of the composite hydrogel was investigated. The results showed that the hydrogel composite presented a good photoantibacterial property, while the antibacterial activity can be neglected under the condition of no light. The complete release of curcumin from the composite was achieved after 120 h. Therefore, the hydrogel system has the characteristics of low cost and high effect, which could be used for an antibacterial sustained-release material. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites have attracted enormous attention due to their remarkable properties for high-efficiency solar cells in recent years. However, controlling the morphology of perovskite films is still a challenge using a solution synthesis method. Perovskite films with incomplete coverage are inevitable and this significantly limits the device photoelectric performance and long-term stability. In this work, we have combined gamma-aminobutyric acid iodide (GABAI) and CH3NH3I (MAI) as a mixed amine source in a precursor solution to fabricate a mixed-cation perovskite (GABA)xMA1−xPbI3. As a result, high quality (GABA)xMA1−xPbI3 crystals were synthesized and showed better pore-filling and more complete contact with the TiO2 scaffold, enhancing the power conversion efficiency from 15.08 to 18.31% with respect to the controlled MAPbI3 solar cells. Importantly, the devices that contained GABA+ also showed much higher stability when compared to the reference MAPbI3 devices. This new chemical modification design, using bifunctional mixed cations in organic–inorganic hybrid perovskites, provides an efficient approach for improving both the performance and stability simultaneously. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid lead halide perovskites are emerging as highly promising candidates for highly efficient thin film photovoltaics due to their excellent optoelectronic properties and low‐temperature process capability. However, the long‐term stability in ambient air still is a key issue limiting their further practical applications. Herein, the enhancement of both performance and stability of perovskite solar cells is reported by employing 2D and 3D heterostructured perovskite films with unique nanoplate/nanocrystalline morphology. The 2D/3D heterostructured perovskites combine advantages of the high‐performance lead‐based perovskite 3D CH3NH3PbI3 (MAPbI3) and the air‐stable bismuth‐based quasi‐perovskite 2D MA3Bi2I9. In the 2D/3D heterostructure, the hydrophobic MA3Bi2I9 platelets vertically situate between the MAPbI3 grains, forming a lattice‐like structure to tightly enclose the 3D MAPbI3 perovskite grains. The solar cell based on the optimal 2D/3D (9.2%) heterostructured film achieves a high efficiency of 18.97%, with remarkably reduced hysteresis and significantly improved stability. The work demonstrates that construction of 2D/3D heterostructured films by hybridizing different species of perovskite materials is a feasible way to simultaneously enhance both efficiency and stability of perovskite solar cells. [ABSTRACT FROM AUTHOR]

The power conversion efficiency (PCE) of perovskite-based solar cells has already exceeded of 22% due to their unique optoelectronic properties. However, the long-term ambient air stability as the Achilles' heel of such promising photovoltaic materials has to be solved for commercialization. Herein, a facile method that partially substitutes B-site Pb2+ by Bi3+ was suggested to enhance moisture tolerance and photovoltaic performances for FAPbI3. The partial incorporation of Bi in FAPbI3 tuned a more favourable tolerance factor and suppressed the phase transition from black perovskite phase to yellow non-perovskite phase at room temperature. The solar cells based on the incorporation of 5 mol% Bi3+ compounds achieved a substantially improved PCE of 17.78%, which is much higher than that of the controlled device with pure FAPbI3 (13.02%). Moreover, the optimal solar cell showed remarkable stability, maintaining 62.38% of the initial PCE without encapsulation for 1000 h under ambient conditions at 25 °C with relative humidity of 30%. This work further demonstrated the possibility of substituting Pb2+ by non-equivalent elements, thus opening the door for further developments of such promising materials. [ABSTRACT FROM AUTHOR]

Methylammonium lead halide (MAPbX3) perovskites have attracted tremendous attention due to their remarkable performances in solar cells, light-emitting diodes, photodetectors, lasers, and electronic memories. However, the issue of toxicity still greatly restricts their further large-scale applications. Here, this study presents a series of nontoxic and stable methylammonium (or cesium) bismuth halides A3Bi2I9 (A = Cs+ and MA+) nanosheets for using in flexible memories. The ultrathin A3Bi2I9 nanosheets can be easily prepared by a dissolution-recrystallization process. This is the first attempt that reports the ultrathin bismuth halides and explores their potential applications in flexible electronic devices. The flexible memristors based on such ultrathin Cs3Bi2I9 nanosheets exhibit typical bipolar resistive switching behavior and remarkable characteristics such as high Ron/ Roff ratio (≈103), very low working voltage (≈0.3 V), and long data retention (>104 s), as well as excellent endurability, reproducibility, environmental stability, and flexibility. With such appealing characteristics, the cesium bismuth halide memristors have great potential for practical applications. The results of this work demonstrate that cesium bismuth halide ultrathin nanosheets will be promising candidates for more emerging applications in electronics and optoelectronics such as memories, photodetectors, photovoltaics, and light-emitting diodes. [ABSTRACT FROM AUTHOR]