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Alloyed lead‐free double perovskites display intense photoluminescence, are environmentally friendly, and their devices show long‐term operation. Thanks to these properties, which make them excellent warm white‐emitting materials, they have recently received great attention in lighting applications. An important factor to tune the optical properties of alloyed lead‐free double perovskites is the presence of self‐trapped excitons. Here, it is demonstrated that in lead‐free double perovskites, the strong electron–phonon coupling plays a crucial role in the generation of self‐trapped excitons. The strong electron–phonon coupling is confirmed by a large Huang–Rhys factor and by the presence of multiphonon transitions. In particular, sharp emission lines superimposed on the broad photoluminescence emission band of one of these samples (Cs2Ag0.6Na0.4InCl6 0.5%Bi) are observed; these are due to the strong coupling of longitudinal‐optical phonons with excited electronic states caused by the tetragonally distorted AgCl6 octahedrons. Such a strong coupling of longitudinal‐optical phonons to electrons can effectively modulate the photophysical properties of alloyed double perovskites, and its understanding is, thus, of paramount importance for the design of future optoelectronic devices. [ABSTRACT FROM AUTHOR]

As "molecular bridge," coupling agents can not only realize the covalent connection of composites, but also affect their properties, thus affecting the properties of devices based on them. Herein, leveraging differences in charge conduction properties of the (3‐aminopropyl)trimethoxysilane and 5,10,15,20‐tetrakis(4‐aminophenyl)‐21H,23H‐porphine caused by conjugacy structural differences, two kinds of layer‐by‐layer assembled smart carbon materials with different electrical properties are obtained at the same reduction temperature. The two graphene ultrathin films are then "planted" on Si/SiO2 substrates, respectively, as semiconductor layer and source/drain electrodes to fabricate an ultra‐stable all‐graphene field effect transistor (AG‐FET). Enabled by the covalent functionalized configuration and the functionally diverse of coupling agents, the AG‐FET obtained by this simple method won the high electrical characteristics, the hole, electron mobility, and the shelflife could reach 3.79 cm2/(V·s), 3.78 cm2/(V·s), and 18 months, respectively. In addition, good material stability and excellent device structure endow the device exceptional stability, electrical stability, and solvent resistance, improving its application prospect in solution phase sensing/detection. Such characteristics could be used to sense, transduce, and respond to external stimuli, especially in solution phase to monitor the important analytes, such as Hg2+ in a flowing sewage environment. We believe that such easy‐to‐manufacture AG‐FETs with ultrahigh performance and ultrahigh stability could also show great application prospects in other significant fields. [ABSTRACT FROM AUTHOR]

The abnormal expression of a microRNA (miRNA) is associated with many major diseases. Therefore, the stability, reliability, and sensitivity of miRNA detection are of paramount importance for early diagnosis and therapeutics. Field‐effect transistor (FET) devices, as sensors, have many advantages, including their multiparameter accessibility and ease of large‐scale manufacturing, but the electrical signals of most FETs are vulnerable in humid environments over extended periods of time, further limiting their sensing capability and performance. In this paper, sophisticated all‐graphene‐based field‐effect transistors (AG‐FETs) are designed and fabricated by means of the covalent layer‐by‐layer (LBL) assembly of graphene oxide (GO), with the electrical capability of FETs and the intrinsic properties of graphene being incorporated in a single device. Thanks to the covalent configuration and the fluorescence quenching properties of graphene, the AG‐FETs possess great electrical stability and outstanding solution resistibility and could detect miRNA sensitively, stably, and reliably through electrical and fluorescence dual signals, which mostly avoid false positives during the test process. This is done without the use of any amplification techniques and even in real samples. These dual‐signal biosensors with excellent performance have promising potential for application in early clinical diagnoses and biomedical research. [ABSTRACT FROM AUTHOR]

The pioneering exfoliation of monolayer tungsten diselenide has greatly inspired researchers toward semiconducting applications. WSe2 belongs to a family of transition‐metal dichalcogenides. Similar to graphene, WSe2 and analogous dichalcogenides have layered structures with weak van der Waals interactions between two adjacent layers. First, the readers are presented with the fundamentals of WSe2, such as types, morphologies, and properties. Here, we report the characterization principles and practices such as microscopy, spectroscopy, and diffraction. Second, the methods for obtaining high‐quality WSe2, such as exfoliation, hydrothermal and chemical vapor deposition, are briefly listed. With advantages of light weight, flexibility, and high quantum efficiency, 2D materials may have a niche in optoelectronics as building blocks in p‐n junctions. Therefore, we introduce a state‐of‐the‐art demonstration of heterostructure devices employing the p‐type WSe2 semiconductor. The device architectures include field‐effect transistors, photodetectors, gas sensors, and photovoltaic solar cells. Due to its unique electronic, optical, and energy band properties, WSe2 has been increasingly investigated due to the conductivity of the p‐type charge carrier upon palladium contact. Eventually, the dynamic research on WSe2 and van der Waals heterostructures is summarized to arouse the passion of the 2D research community. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting offers a promising strategy for converting solar energy to chemical fuels. Herein, a piezoelectric‐effect–enhanced full‐spectrum photoelectrocatalysis with multilayered coaxial titanium dioxide/barium titanate/silver oxide (TiO2/BTO/Ag2O) nanorod array as the photoanode is reported. The vertically grown nanorods ensure good electron conductivity, which enables fast transport of the photogenerated electrons. Significantly, the insertion of a piezoelectric BaTiO3 (BTO) nanolayer at the p‐type Ag2O and n‐type TiO2 interface created a polar charge‐stabilized electrical field. It maintains a sustainable driving force that attract the holes of TiO2 and the electrons of Ag2O, resulting in greatly increased separation and inhibited recombination of the photogenerated carriers. Furthermore, Ag2O as a narrow bandgap semiconductor has a high ultraviolet–visible–near infrared (UV–vis–NIR) photoelectrocatalytic activity. The TiO2/BTO/Ag2O, after poling, successfully achieves a prominent photocurrent density, as high as 1.8 mA cm−2 at 0.8 V versus Ag/Cl, which is about 2.6 times the TiO2 nanorod photoanode. It is the first time that piezoelectric BaTiO3 is used for tuning the interface of p‐type and n‐type photoelectrocatalyst. With the enhanced light harvesting, efficient photogenerated electron–hole pairs' separation, and rapid charge transfer at the photoanode, an excellent photoelectrocatalytic activity is realized. [ABSTRACT FROM AUTHOR]