The coherent developments of high performance broadband photodetection and a discrimination technique are highly essential for multiscene imaging and optical communication applications. The integration of traditional bandpass filters or stacking other spectral absorber in photodetectors often complicates the device design and leads to asymmetric photogain for each waveband. Herein, we report on ultraviolet–visible (UV-vis) multispectral photodetection based on a single ZnO nanowire (NW) phototransistor, where defect reconstructions can be reliably induced by a two-step annealing that leads to the observed broadband photodetection. Electron paramagnetic resonance and photoluminescence spectra reveal the reconstructions of zinc-atom-related defects (i.e., zinc interstitials and vacancies). Combined microdifferential reflectance and multimode scanning probe microscope (SPM) technique confirm the presence of a unique visible-sensitive Zn-rich ZnO shell layer and a trap-free UV-sensitive ZnO core. We achieve not only an ultrahigh carrier mobility (212.4 cm2 V–1 s–1), but also a concurrent improvement for UV-vis photodetection with superior responsivities and detectivities on the orders of 105 AW–1 and 1015 Jones at 100 mV, respectively, and response speeds less than one second. Moreover, photocurrents under blue, green, and red stimuli can be selectively switched on/off by tuning the gate stress. These high performances in all figures of merit have opened new routes to tailor intrinsic properties of a single NW for optoelectronic applications.

Polycrystalline film photodetectors often suffer from several drawbacks, such as uncontrollable defect species, grain boundary scattering, and surface oxygen trapping/detrapping, hindering their practical applications in high-performance UV photodetection. In this work, we induce an acceptor-type zinc vacancy (VZn) defect in zero-dimensional ZnO nanocrystals by a dual thermal annealing process, which has been closely examined by a defect-sensitive electron paramagnetic resonance technique. The optimization of annealing parameters can well tune the VZn concentration and induce a considerable self-powered behavior, which is believed to result from ionized acceptor enhanced charge separation. On the other aspect, the capping of metallic Zn can lead to the formation of abundant interface conducting channels for the highly efficient charge transport and extraction. The optimized responsivity is enhanced from 5.3 × 10–3 to 15.3 A W–1, and the average rise and decay times remain at 36.6 and 101.8 ms, respectively. Conductive atomic force microscopy confirms a uniform photocurrent distribution in the annealed polycrystalline films, suggesting the significance of synergies of lattice defects and grain boundary conductive channels. This study unambiguously demonstrates a new route to engineer the photodetection in nanocrystalline oxides, providing a promising prospect for future low-cost, low-power-consumption micro-/nano-optoelectronic devices.

spectroscopy (ICP-AES), and surface plasmon resonance sensing. [4][5][6] Although these methods have high detection performances, the complicated preprocessing process and the excessive cost limit their range of use and the detection rate. On the other hand, with the advancement of fluorescence technology, fluorescence detection techniques for metal ions by monitoring the fluorescence enhancement, quenching, or shifting of peak positions have attracted great interests. This type of method has advantages of strong visibility, simple operation, wide detection range, and low price. [7] Recently, quantum dot (QD) fluorescent probes are gradually receiving more attentions. Compared with the traditional organic fluorescent materials, QD fluorescent probes have narrower emission spectra, better stability, and photobleaching resistance. For example, carbon QDs, [8,9] CdSe QDs, [10] CdS QDs, [11] perovskites QDs, [12] and a combination of functional molecules and QDs have been studied to detect metal ions such as Fe 3+ , Pb 2+ , Hg 2+ , Zn 2+ , and Cd 2+ . [13][14][15][16][17][18] However, currently reported fluorescent probes can be used in only one solvent, it is therefore necessary to develop fluorescent probes with strong selectivity, wide detection range, and low detection limit, which can be used in both aqueous and organic solutions.Black phosphorus (BP) as one of the three major allotropes of phosphorus is a 2D van der Waals material whose atomic layers are stacked by weak van der Waals forces. BP can be stripped into nanosheets down to a single layer or quantum dots with bandgaps varying from 0.3 (bulk BP) to 2.0 eV. Due to this unique property, BP has the size and composition-dependent light absorption, long exciton lifetime, high photo luminescence quantum yield, and ability of surface modification. So far, BP has been used as photothermal agents, photodetectors, photocatalysts, organic photovoltaics, electrocatalysts, and the storage media. [19][20][21][22][23][24] BP has also been studied in the field of sensors, such as humidity sensors, [25] ratiometric fluorescent probes developed by the surface modification of organic molecules, [26,27] field effect transistor detection of metal ions. [28] In addition, BP has a wide range of applications in the biological field, including the medicine, drug carriers, and cancer treatment. [29][30][31] In this research, we have successfully prepared black phosphorus quantum dots (BP QDs) with green fluorescence emission, which can directly detect trace Hg 2+ and Cu 2+ ions without the help of organic molecules. In particular, Fluorescence method for detecting metal ions has advantages of fast detection speed, simple operation, and low price over the conventional methods. Black phosphorus quantum dots (BP QDs) have high photoluminescence quantum yield and modifiable surface, which have great potential in the field of fluorescent probes. In this study, high quality BP QDs are prepared by pyrolysis method and are first time used as trace metal ion probes in both organic solut...

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The electric field control of Raman scattering for small molecules can be realized in direct semiconducting antimonene-based field effect transistor.

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Bi2O2Se has established itself as a revolutionary two-dimensional (2D) semiconductor owing to its superior electric, optoelectric and thermoelectric properties. The structural compatibility between Bi2O2Se and perovskite oxides makes the investigation...

Flexible and transparent optoelectronics based on 2D materials are promising candidates for next‐generation technologies. Among all 2D materials, it is of numerous practical implications to explore nonmetal, earth‐abundant candidates. Herein, an exciting addition is unearthed—2D hydrogenized amorphous carbon (α‐C:H). The 2D α‐C:H nanosheets, with layered structural feature, are composed of crystalline sp2 nanoclusters embedded in sp3 amorphous matrix. The typical “vapor–solid” mechanism governs the growth of these nanosheets under the temperature–pressure combination above the Berman–Simon line. Their high transmittance over 97.7% covers the 425–1300 nm wavelength region. Optical characterizations also reveal a spectral overlap between the π–π* absorption edge and σ–σ* photoluminescence peak. Self‐powered and flexible photodetectors based on the 2D α‐C:H/ZnO heterostructure exhibit a remarkable photoresponse, with a broadened photosensitivity responsivity of 195.16 mA W−1 and a 267‐fold decrease of the rise time. This performance enhancement originates from the type II band alignment, the pyroelectric and piezo‐phototronic effects. As a new member in the 2D family, α‐C:H nanosheets promise to be appealing in transparent flexible optoelectronics with ultralow power consumption and real‐time, on‐site response.