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Two-dimensional materials provide opportunities for developing semiconductor applications at atomistic thickness to break the limits of silicon technology. Black phosphorus (BP), as a layered semiconductor with controllable bandgap and high carrier mobility, is one of the most promising candidates for transistor devices at atomistic thickness1–4. However, the lack of large-scale growth greatly hinders its development in devices. Here, we report the growth of ultrathin BP on the centimetre scale through pulsed laser deposition. The unique plasma-activated region induced by laser ablation provides highly desirable conditions for BP cluster formation and transportation5,6, facilitating growth. Furthermore, we fabricated large-scale field-effect transistor arrays on BP films, yielding appealing hole mobility of up to 213 and 617 cm2 V−1 s−1 at 295 and 250 K, respectively. Our results pave the way for further developing BP-based wafer-scale devices with potential applications in the information industry. Centimetre-scale growth of few-layer black phosphorous with high crystalline quality and homogeneity is realized by pulsed laser deposition.

Summary With amazing progress in the state-of-the-art perovskite solar cells (PSCs) fabricated by laboratory-scale spin-coating methods, upscaling the PSCs via printing friendly techniques is becoming more and more important toward the future deployment of large-scale and stable perovskite modules. Here, we demonstrate the room-temperature meniscus coating of high-quality perovskite films incorporated with a multifunctional sulfobetaine-based zwitterionic surfactant. Systematic in situ studies uncover the perovskite crystallization pathway and emphasize the surfactant’s synergistic role in film construction, crystallization kinetics modulation, defect passivation, and moisture barrier protection. This strategy is applicable across perovskite compositions and device architectures with the enhanced power conversion efficiencies up to 22%. Upscaling the device area to 0.8 cm2 has negligible deterioration in the performance. This represents one of the highest records for the upscaling coated PSCs, not limited in room-temperature coated PSCs. In addition, this approach significantly improves the stability of perovskite films and devices under different aging conditions.

Perovskite solar cells (PSCs) are promising technology for flexible photovoltaic applications because of the low cost and good flexibility of the halide perovskite materials. Nevertheless, the use of transparent conductive oxides (TCOs) and noble metals (e.g., Au and Ag) as PSC electrodes is very costly, and TCOs are too brittle for flexible applications. How to fabricate flexible PSCs (FPSCs) with cost-effective and soft electrode materials remains to be a big challenge. Herein, we report the first study of FPSCs using low-cost Cu electrodes. Both the transparent bottom electrode and the opaque top electrode are fabricated with Cu. FPSCs made with such Cu electrodes acquire a champion efficiency of 13.58% (Jsc of 17.79 mA cm-2, Voc of 1.031 V, and FF of 74.07%), which retains over 90% after 1000 cycles of bending at a small radius of curvature of 5 mm. The device shows negligible changes in Voc and FF after storage for 10 weeks without encapsulation.

Hybrid perovskite single-crystalline thin films are promising for making high-performance perovskite optoelectronic devices due to their superior physical properties. However, it is still challenging to incorporate them into multilayer devices because of their on-substrate growth. Here, a wet transfer method is used in transferring perovskite single-crystalline films perfectly onto various target substrates. More importantly, large millimeter-scaled single-crystalline films can be obtained via a diffusion-facilitated space-confined growth method as thin as a few hundred nanometers, which are capable of sustaining excellent crystalline quality and morphology after the transferring process. The availability of these crystalline films offers us a convenient route to further investigate their intrinsic properties of hybrid perovskites. We also demonstrate that the wet transfer method can be used for scalable fabrication of perovskite single-crystalline film-based photodetectors exhibiting a remarkable photoresponsivity. It is expected that this transferring strategy would promise broad applications of perovskite single-crystalline films for more complex perovskite devices.

After the breakthrough of the study on the two-dimensional (2D) layered phosphorus, group-V elemental ultrathin 2D layers have captured considerable attentions in recent years on account of their unique and promising electrical transport properties, including semiconductor features with direct and desirable energy band structures, outstanding carrier mobilities, controllable and tunable characteristics under applied strain, electric and magnetic fields, highly anisotropic phenomena along both in-plane and out-plane directions, topological transmission states, and negative Poisson’s ratio. Accordingly, a number of investigations on this family of 2D materials have been conducting rapidly, while initiating great potential and new opportunities on the nanoscale science and applications in optoelectronic, magneto-electronics, thermo-electronic, ferroelectric, topological spintronics, and so on. Herein, a specific review is provided with systematical summarizations and refinements on the recent advances of the electrical transport in group-V elemental ultrathin 2D layers from the blossoming field of research, while comprehensive discussion and some recommendations are put forward, with an expectation of broadening and deepening understanding of the family of 2D layers. Lastly, we provide critical motivation and challenge for future explorations in this promising territory.

Lanthanide ions have attracted great attention due to their distinct photonic properties. The optoelectronic properties and device performance are greatly affected by the interfacial coupling between the layered van der Waals heterostructure, fabricated with two or more transition metal dichalcogenide (TMD) layers. In this work, lanthanide-doped WS2/MoS2 layered heterostructures have been constructed through two synthesis steps. The doped thin films are highly textured nanosheets on wafers. Importantly, the as-prepared heterostructure exhibits efficient near-infrared emission in the range of the telecommunication window, owing to energy transfer between lanthanide ions in the two TMD layers. The use of the layered heterostructure allows the decrease of deleterious cross-relaxation due to homogeneous doping or concentration quenching. The energy transfer process was further elaborated in this work. The results suggest that lanthanide ions can effectively extend the emission band of TMD thin films and their heterostructures. The doped TMD heterostructure is highly favourable for constructing atomically thin near-infrared photonic devices.

Objective The precise localization of intracranial electrodes is a fundamental step relevant to the analysis of intracranial electroencephalography (iEEG) recordings in various fields. With the increasing development of iEEG studies in human neuroscience, higher requirements have been posed on the localization process, resulting in urgent demand for more integrated, easy-operation and versatile tools for electrode localization and visualization. With the aim of addressing this need, we develop an easy-to-use and multifunction toolbox called iEEGview, which can be used for the localization and visualization of human intracranial electrodes. Approach iEEGview is written in Matlab scripts and implemented with a GUI. From the GUI, by taking only pre-implant MRI and post-implant CT images as input, users can directly run the full localization pipeline including brain segmentation, image co-registration, electrode reconstruction, anatomical information identification, activation map generation and electrode projection from native brain space into common brain space for group analysis. Additionally, iEEGview implements methods for brain shift correction, visual location inspection on MRI slices and computation of certainty index in anatomical label assignment. Main results All the introduced functions of iEEGview work reliably and successfully, and are tested by images from 28 human subjects implanted with depth and/or subdural electrodes. Significance iEEGview is the first public Matlab GUI-based software for intracranial electrode localization and visualization that holds integrated capabilities together within one pipeline. iEEGview promotes convenience and efficiency for the localization process, provides rich localization information for further analysis and offers solutions for addressing raised technical challenges. Therefore, it can serve as a useful tool in facilitating iEEG studies.

2D hybrid perovskites are very attractive for optoelectronic applications because of their numerous exceptional properties. The emerging 2D perovskite ferroelectrics, in which are the coupling of spontaneous polarization and piezoelectric effects, as well as photoexcitation and semiconductor behaviors, have great appeal in the field of piezo-phototronics that enable to effectively improve the performance of optoelectronic devices via modulating the electro-optical processes. However, current studies on 2D perovskite ferroelectrics focus on bulk ceramics that cannot endure irregular mechanical deformation and limit their application in flexible optoelectronics and piezo-phototronics. Herein, we synthesize ferroelectric EA4 Pb3 Br10 single-crystalline thin-films (SCFs) for integration into flexible photodetectors. The in-plane multiaxial ferroelectricity is evident within the EA4 Pb3 Br10 SCFs through systematic characterizations. Flexible photodetectors based on EA4 Pb3 Br10 SCFs are achieved with an impressive photodetection performance. More importantly, optoelectronic EA4 Pb3 Br10 SCFs incorporated with in-plane ferroelectric polarization and effective piezoelectric coefficient show great promise for the observation of piezo-phototronic effect, which is capable of greatly enhancing the photodetector performance. Under external strains, the responsivity of the flexible photodetectors can be modulated by piezo-phototronic effect with a remarkable enhancement up to 284%. Our findings shed light on the piezo-phototronic devices and offer a promising avenue to broaden functionalities of hybrid perovskite ferroelectrics.

α-Formamidinium lead triiodide (α-FAPbI3 ) represents the state-of-the-art for perovskite solar cells (PSCs) but experiences intrinsic thermally induced tensile strain due to a higher phase-converting temperature, which is a critical instability factor. An in situ crosslinking-enabled strain-regulating crystallization (CSRC) method with trimethylolpropane triacrylate (TMTA) is introduced to precisely regulate the top section of perovskite film where the largest lattice distortion occurs. In CSRC, crosslinking provides in situ perovskite thermal-expansion confinement and strain regulation during the annealing crystallization process, which is proven to be much more effective than the conventional strain-compensation (post-treatment) method. Moreover, CSRC with TMTA successfully achieves multifunctionality simultaneously: the regulation of tensile strain, perovskite defects passivation with an enhanced open-circuit voltage (VOC = 50 mV), and enlarged perovskite grain size. The CSRC approach gives significantly enhanced power conversion efficiency (PCE) of 22.39% in α-FAPbI3 -based PSC versus 20.29% in the control case. More importantly, the control PSCs' instability factor-residual tensile strain-is regulated into compression strain in the CSRC perovskite film through TMTA crosslinking, resulting in not only the best PCE but also outstanding device stability in both long-term storage (over 4000 h with 95% of initial PCE) and light soaking (1248 h with 80% of initial PCE) conditions.

Extensive studies are conducted on perovskite solar cells (PSCs) with significant performance advances (mainly spin coating techniques), which have encouraged recent efforts on scalable coating techniques for the manufacture of PSCs. However, devices fabricated by blade coating techniques are inferior to state‐of‐the‐art spin‐coated devices because the power conversion efficiency (PCE) is highly dependent on the morphology and crystallization kinetics in the controlled environment and the delicate solvent system engineering. In this study, based on the widely studied perovskite solution system dimethylformamide–dimethyl sulfoxide, air‐knife‐assisted ambient fabrication of PSCs at a high relative humidity of 55 ± 5% is reported. In‐depth time‐resolved UV–vis spectrometry is carried out to investigate the impact of solvent removal and crystallization rate, which are critical factors influencing the crystallization kinetics and morphology because of adventitious moisture. UV–vis spectrometry enables accurate determination of the thickness of the wet precursor film. Anti‐solvent‐free, high‐humidity ambient coatings of hysteresis‐free PSCs with PCEs of 21.1% and 18.0% are demonstrated for 0.06 and 1 cm2 devices, respectively. These PSCs exhibit comparable stability to those fabricated in a glovebox, thus demonstrating their high potential., In this work, a perovskite solar cell (PSC) is fabricated via a scalable solution process under ambient conditions. A hysteresis‐free, high‐efficiency (21.1%), laminar‐air‐knife‐assisted meniscus coating of PSCs is demonstrated at room temperature and a relative humidity of 55%. An in‐depth in situ investigation by time‐resolved UV–vis spectroscopy is conduced to explore the nucleation dynamics.

Stereo-electroencephalographic (SEEG) depth electrodes were used to record neural activity from deep brain structures in this study. By localizing all the electrodes into the individual brain, we found that areas that are inside of central sulcus occurred obvious hand-movement-related modulation when the subjects were performing different hand motion tasks. Then, an asynchronous brain-computer interface which enables the subject to control a prosthetic hand in real time was built. The testing results showed that, using the SEEG signals taken only from five channels, all the participants can not only control the robot prosthesis to be motionless but also can command the device to make three different hand gestures successfully with an average accuracy of 78.70±4.01%.

The near-infrared (NIR) emission of Er3+ ions has been extensively studied owing to their significance in optical communication applications. However, studies concerning the incorporation of lanthanide ions into the two-dimensional (2D) matrix are still in the early stages. In this work, we developed an ingenious two-step vapor-phase-transfer method to synthesize Er3+ doped MoS2 single-crystalline monolayers. The NIR emission at 1530 nm was observed from the doped MoS2 nanosheets under 980 nm diode laser excitation, corresponding to the energy transition from 4I13/2 to 4I11/2 of the Er3+ dopant. The concentration quenching effect was demonstrated with an optimal Er content of around 4 mol. %. To further understand the effect of lanthanide doping on the 2D MoS2 host matrix in terms of the growth mechanism and electronic structures, theoretical analysis was performed on Er-doped monolayer MoS2 using the density functional theory calculation. The computed band structure with the superimposed Dieke diagram was in good accordance with our experimental results. Our work offers the possibility to develop doping strategies in the 2D limit and provides an in-depth understanding of the lanthanide doping in atomically thin materials.