Large single crystals serve as an ideal platform for investigating intrinsic material properties and optoelectronic applications. Here we develop a method, namely, room-temperature liquid diffused separation induced crystallization that uses silicone oil to separate the solvent from the perovskite precursors, to grow high-quality perovskite single crystals. The growth kinetics of perovskite single crystals using this method is elucidated, and their structural and optoelectronic properties are carefully characterized. The resultant perovskite single crystals, taking CH3NH3PbBr3 as an example, exhibit approximately 1 µs lifetime, a low trap density of 4.4 × 109 cm−3, and high yield of 92%, which are appealing for visible light or X-ray detection. We hope our findings will be of great significance for the continued advancement of high-quality perovskite single crystals, through a better understanding of growth mechanisms and their deployment in various optoelectronics. The diffused separation induced crystallization strategy presents a major step forward for advancing the field on perovskite single crystals.

Metal selenides have great potential for electrochemical energy storage, but are relatively scarce investigated. Herein, a novel hollow core-branch CoSe nanoarray on carbon cloth is designed by a facile selenization reaction of predesigned CoO nanocones. And the electrochemical reaction mechanism of CoSe in supercapacitor is studied in detail for the first time. Compared with CoO, the hollow core-branch CoSe has both larger specific surface area and higher electrical conductivity. When tested as a supercapacitor positive electrode, the CoSe delivers a high specific capacitance of 759.5 F g at 1 mA cm , which is much larger than that of CoO nanocones (319.5 F g ). In addition, the CoSe electrode exhibits excellent cycling stability in that a capacitance retention of 94.5% can be maintained after 5000 charge-discharge cycles at 5 mA cm . An asymmetric supercapacitor using the CoSe as cathode and an N-doped carbon nanowall as anode is further assembled, which show a high energy density of 32.2 Wh kg at a power density of 1914.7 W kg , and maintains 24.9 Wh kg when power density increased to 7354.8 W kg . Moreover, the CoSe electrode also exhibits better oxygen evolution reaction activity than that of CoO.

Porous CoSe on carbon cloth is prepared from a cobalt-based metal organic framework template with etching and selenization reaction, which has both a larger specific surface area and outstanding electrical conductivity. As the catalyst for oxygen evolution reaction, the porous CoSe achieves a lower onset potential of 1.48 V versus the reversible hydrogen electrode (RHE) and a small potential of 1.52 V (vs RHE) at an anodic current density of 10 mA cm. Especially, the linear sweep voltammogram curve of the porous CoSe is in consist with the initial curve after durability test for 24 h. When tested as an electrode for supercapacitor, it can deliver a specific capacitance of 713.9 F g at current density of 1 mA cm and exhibit excellent cycling stability in that a capacitance retention of 92.4% can be maintained after 5000 charge-discharge cycles at 5 mA cm. Our work presents a novel strategy for construction of electrochemical electrode.

Perovskite photodetectors (PDs) with tunable detection wavelength have attracted extensive attention due to the potential application in the field of imaging, machine vision, and artificial intelligence. Most of the perovskite PDs focus on I‐ or Br‐based materials due to their easy preparation techniques. However, their main photodetection capacity is situated in the visible region because of their narrower bandgap. Cl‐based wide bandgap perovskites, such as CsPbCl3, are scarcely reported because of the bad film quality of the spin‐coated Cl‐based perovskite, due to the poor solubility of the precursor. Therefore, ultraviolet detection using high‐quality full inorganic perovskite films, especially with high thermal stability of materials and devices, is still a big challenge. In this work, high‐quality single crystal CsPbCl3 microplatelets (MPs) synthesized by a simple space‐confined growth method at low temperature for near‐ultraviolet (NUV) PDs are reported. The single CsPbCl3 MP PDs demonstrate a decent response to NUV light with a high on/off ratio of 5.6 × 103 and a responsivity of 0.45 A W−1 at 5 V. In addition, the dark current is as low as pA level, leading to detectivity up to 1011 Jones. Moreover, PDs possess good stability and repeatability.

An appropriately combined triple interface modification, i.e., post-annealing, O2-plasma, and KCl treatments, is employed to ameliorate the optoelectronic properties of sputtered NiOx films and achieve better device performance.

In recent years, hybrid organic–inorganic perovskites have emerged as promising photosensing materials for next-generation solution-processed photodetectors, achieving high responsivity, fast speed, and large linear dynamic range. In particular, perovskite photoresistors possess low-cost fabrication and easy integration with low dimensional structures. However, a relatively large dark current is still limiting the further development of perovskite photoresistors. Herein, we introduce full-inorganic perovskite polycrystalline microwires for high-performance photodetection, in order to enhance the device stability. Furthermore, dark current and noise can be effectively suppressed by tuning the contacts. All-inorganic CsPbBr3 microwires with a number of nanocrystals on the wire surface are prepared by a simple, low-cost, two-step, solution-processed method at room temperature. Photodetectors based on this CsPbBr3 polycrystalline single microwire are assembled on indium tin oxide electrodes and demonstrate a decent responsivity up to 118 A/W and a fast response within 40 ms. In addition, such optimized photoresistors possess a fairly tiny dark current and noise, which result in an improved detectivity of >1012 Jones and demonstrate excellent characteristics to detect weak light.

A self-powered, visible-blind ultraviolet photodetector based on n-ZnO nanorods/i-MgO/p-GaN structure light-emitting diode.

Bifunctional bamboo-like CoSe arrays are synthesized by thermal annealing of Co(CO)OH grown on carbon cloth in Se atmosphere. The CoSe arrays obtained have excellent electrical conductivity, larger electrochemical active surface areas, and can directly serve as a binder-free electrode for supercapacitors and the oxygen evolution reaction (OER). When tested as a supercapacitor electrode, the CoSe delivers a higher specific capacitance (544.6 F g at current density of 1 mA cm) compared with CoO (308.2 F g) or CoO (201.4 F g). In addition, the CoSe electrode possesses excellent cycling stability. An asymmetric supercapacitor (ASC) is also assembled based on bamboo-like CoSe as a positive electrode and active carbon as a negative electrode in a 3.0 M KOH aqueous electrolyte. Owing to the unique stucture and good electrochemical performance of bamboo-like CoSe, the as-assembled ACS can achieve a maximum operating voltage window of 1.7 V, a high energy density of 20.2 Wh kg at a power density of 144.1 W kg, and an outstanding cyclic stability. As the catalyst for the OER, the CoSe exhibits a lower potential of 1.55 V (versus RHE) at current density of 10 mA cm, a smaller Tafel slope of 62.5 mV dec and an also outstanding stability.