in order to restrict the loss of material. Furthermore, due to their scalability and flexibility, 3D flexible electronics (see Supporting Information (SI), where Table S1 contains a list) were considered revolutionary materials and were used in many fields such as imperceptible electronic devices, wearable electronic devices, and bionic technology. [11][12][13] Recently studies have shown the encapsulation of sulfur in the pores of carbon materials, such as meso-/microporous carbons, [11] cable-shaped carbon, [12] and carbon nanotubes/fibers, [13] can reduce the capacity fading. However, such nonpolar flexible carbon materials have a destructive disadvantage; they only have physical van der Waals (vdW) adsorption for polar Li 2 S n , which leads to the facile detachment of Li 2 S n from the carbon surface. [14] This proves that carbon-based materials alone cannot serve as the perfect host. In light of this new insight, various types of polar functional groups on carbon-based materials have been demonstrated to increase the interaction between Li 2 S n species and the electrode; these materials can generally be categorized into three types: polymers (polyaniline, polypyrrole, poly(3,4ethylenedioxythiophene) (PEDOT)), [15] metal oxides

Self-powered flexible photodetectors without an external power source can meet the demands of next-generation portable and wearable nanodevices; however, the performance is far from satisfactory becuase of the limited match of flexible substrates and light-sensitive materials with proper energy levels. Herein, a novel self-powered flexible fiber-shaped photodetector based on double-twisted perovskite-TiO -carbon fiber and CuO-Cu O-Cu wire is designed and fabricated. The device shows an ultrahigh detectivity of 2.15 × 10 Jones under the illumination of 800 nm light at zero bias. CuO-Cu O electron block bilayer extends response range of perovskite from 850 to 1050 nm and suppresses dark current down to 10 A. The fast response speed of less than 200 ms is nearly invariable after dozens of cycles of bending at the extremely 90 bending angle, demonstrating excellent flexibility and bending stability. These parameters are comparable and even better than reported flexible and even rigid photodetectors. The present results suggest a promising strategy to design photodetectors with integrated function of self-power, flexibility, and broadband response.

Flexible perovskite photodetectors are usually constructed on indium-tin-oxide-coated polymer substrates, which are expensive, fragile, and not resistant to high temperature. Herein, for the first time, a high-performance flexible perovskite photodetector is fabricated based on low-cost carbon cloth via a facile solution processable strategy. In this device, perovskite microcrystal and Spiro-OMeTAD (hole transporting material) blended film act as active materials for light detection, and carbon cloth serves as both a flexible substrate and a conductive electrode. The as-fabricated photodetector shows a broad spectrum response from ultraviolet to near-infrared light, high responsivity, fast response speed, long-term stability, and self-powered capability. Flexible devices show negligible degradation after several tens of bending cycles and at the extremely bending angle of 180°. This work promises a new technique to construct flexible, high-performance photodetectors with low cost and self-powered capability.

Lead halide perovskite solar cells (PSCs) with the high power conversion efficiency (PCE) typically use mesoporous metal oxide nanoparticles as the scaffold and electron-transport layers. However, the traditional mesoporous layer suffers from low electron conductivity and severe carrier recombination. Here, antimony-doped tin oxide nanorod arrays are proposed as novel transparent conductive mesoporous layers in PSCs. Such a mesoporous layer improves the electron transport as well as light utilization. To resolve the common problem of uneven growth of perovskite on rough surface, the dynamic two-step spin coating strategy is proposed to prepare highly smooth, dense, and crystallized perovskite films with micrometer-scale grains, largely reducing the carrier recombination ratio. The conductive mesoporous layer and high-quality perovskite film eventually render the PSC with a remarkable PCE of 20.1% with excellent reproducibility. These findings provide a new avenue to further design high-efficiency PSCs from the aspect of carrier transport and recombination.

low-temperature solution method, which makes it a promising candidate for flexible devices. [19][20][21][22][23] Novel devices based on perovskite have proven great potential for further application. [24][25][26] However, perovskites are very sensitive to air moisture which invades cracks of flexible films and accelerates the damage to devices. In the base of environmental protection, the toxicity of lead also demands for long working life for perovskite devices to avoid the disposal of lead waste. [27][28][29] These problems indicate that mechanical stability remains as a significant concern for flexible perovskite devices. Solutions including interface treatment and mixture of polymer have been employed, but they can only withstand limited bending cycles and strength. [30][31][32][33][34] To resolve these critical issues, the concept of self-healing has also been applied to flexible perovskite devices. [35,36] Selfhealing polymers can act as encapsulation layers or flexible substrates, which only prevent external air moisture while cracks inside perovskite films still exist and block carrier transport. In addition, it is difficult to endow the ABX 3 crystal structure of perovskite with special chemical bonds (such as H-bonds) to trigger the capability of self-healing. To address this challenge, Chen et al. creatively utilized polyurethanes (PU) to provide a micro-self-healing framework for perovskite crystals without damaging its power conversion efficiency and cracks caused by stretching were healed by heating films at 100 °C. [36] The heating treatment may damage organic carrier transport layers or accelerate ion diffusion of metal electrodes; moreover, perovskite devices usually operate at the room temperature. Thus, it is necessary to design a perovskite material with self-healing capability which does not need any harsh external stimuli.Herein, we design a moisture-triggered self-healing flexible perovskite photodetector with poly(vinyl alcohol) (PVA) as an additive. Moisture, as a negative factor affecting the stability of perovskite, is also used to activate the self-healing process of perovskite films. PVA organic framework fills grain boundaries, which are weak points that generate cracks. The moisturesensitive framework absorbs water molecules from the air and recovers the conductivity lost from the cracks, which is proved to be the dominant reason for the decomposition of the flexible lateral perovskite photodetector. The device can recover over 90% of its initial performance under a relative humidity (RH) of 80%, maintaining remarkable mechanical stability. Furthermore, PVA stabilizes the formamidinium lead iodide (FAPbI 3 ) film in the black phase, and the photodetector shows a high responsivity Flexible devices are urgently required to meet the demands of next-generation optoelectronic devices and metal halide perovskites are proven to be suitable materials for realizing flexible photovoltaic devices. However, the tolerance to moisture corrosion and repeated mechanical bending remains a critical c...

Integration of various photodetectors with different light‐sensitive materials and detection capacity is an inevitable way to achieve entire color/spectrum detection. However, the uneven capacity of each photodetector would drag the overall performance behind, especially the response speed. A response time down to nanosecond level has not previously been reported for a filter‐free color/spectrum‐sensitive photodetector, as far as is known. Here, a self‐powered filterless color‐sensitive photodetection array based on an in situ formed gradient perovskite absorber film with continuously tunable bandgap is demonstrated. Ultrahigh‐speed response at nanosecond level is achieved in all the ingredient photodetectors. The junction capacitance being influenced by carrier concentration in the absorber is identified to be responsible for the detection speed. Without any optic or mechanical supporting system, the designed color detector exhibits an external quantum efficiency (EQE) up to 94% and a high spectral resolution of around 80 nm for the whole visible spectrum. This work offers a guidance to achieve fast response of perovskite‐based photodetectors from the point of view of carrier‐donor control and demonstrates a new avenue to establish color‐sensitive photodetectors/spectrometers.

Cesium lead mixed‐halide perovskite (CsPbIBr2), as one of the all‐inorganic perovskites, has attracted great attention owing to its great ambient stability and suitable bandgap. Unfortunately, due to its low film coverage, high density of defects and unfavorable band energy level, the CsPbIBr2 based solar cells suffer from low efficiency. In this work, the Lewis base poly(ethylene glycol) (PEG) is adopted as additive to modify the pure CsPbIBr2. By optimizing the molecular weight and dosage of PEG, the resultant PEG:CsPbIBr2 film possesses suppressed non‐radiative electron–hole recombination, a favorable energy band structure and a weaker sensitive to the moisture. As a result, the device based on the PEG:CsPbIBr2 yields a champion power conversion efficiency (PCE) of 11.10%, with a open‐circuit voltage of 1.21 V, a short‐circuit current of 12.25 mA cm−2, and a fill factor of 74.82%, which is 44.3% higher than its counterpart without PEG. Moreover, the PEG modified device shows excellent long‐term stability, retaining over 90% of the initial efficiency after 600 h storage in ambient condition without encapsulation. In comparison, the device without PEG shows an inferior stability with PCE sharply dropping to 0% within 50 h.

Due to its excellent electrical and optical features, silicon (Si) is highly attractive for photodetector applications. The design and fabrication of low‐dimensional semiconductor/Si hybrid heterostructures provide a great platform for fabricating high‐performance photodetectors, thereby overcoming the inherent limitations of Si. This review focuses on state‐of‐the‐art Si heterostructure‐based photodetectors. It starts with the introduction of three different device configurations, that is, photoconductors, photodiodes, and phototransistors. Their working mechanisms and relative pros and cons are introduced, and the figures of merit of photodetectors are summarized. Then, we discuss the device physics/design, photodetection performance, and optimization strategies for Si‐based photodetectors. Finally, future challenges in the photodetector applications of Si‐based hybrid heterostructures are discussed.