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Zero-dimensional (0D) organic–inorganic metal halide hybrids (MHHs) are considered promising luminescent materials due to their unique "host–guest" structure and tunable emission spectrum. Herein, we successfully prepared Sb3+-doped 0D (CH6N3)3BiCl6 single crystals using an evaporation solvent method. The introduction of Sb3+ results in a bright orange emission with a center wavelength of 610 nm. On increasing the Sb3+ doping level to 20%, the doped sample achieves the highest photoluminescence quantum yield (PLQY) of 53%, attributed to the formation of self-trapped excitons (STEs) induced by the strong interaction between electrons and the crystal lattice. Interestingly, Sb3+-doped (CH6N3)3BiCl6 exhibits rapidly reversible ethanol-responsive luminescence transition between orange and yellow emissions. This class of 0D MHHs exhibits high sensitivity and repeatability as a fluorescent probe for ethanol detection, demonstrating significant potential in environmental monitoring and ethanol detection applications. [ABSTRACT FROM AUTHOR]

Lead-based metal halides are widely investigated and applied in many fields such as light emitting diodes (LEDs), photovoltaic devices, sensors, and solar cells for their superior optical properties. However, the problem of poor stability hinders their further commercial applications. Herein, we report new all-inorganic zero-dimensional (0D) Sb3+-doped (NH4)4CdCl6 halides with highly efficient emission and stability. Under UV excitation, the emission efficiency of pristine (NH4)4CdCl6 is extremely low. However, with the introduction of optically active Sb3+, the doped (NH4)4CdCl6 showed a bright orange-yellow emission centered at 570 nm, and photoluminescence quantum yield (PLQY) reached up to 62%, which can be attributed to the unique "host–guest" structure of the 0D metal halides. By maintaining the structure type, warm white light could be tuned by A-site Rb alloying, and a PLQY of 71% could be achieved. This work is aimed to explore the emission mechanism of Sb3+ doped Cd-based metal halides, which are promising and efficient photoelectric materials with emission of Sb3+ triplet states. In addition, this research explored the structural diversity of 0D metal halides, providing design principles for warm white LEDs. [ABSTRACT FROM AUTHOR]

Substantial progress has been made in light-emitting diodes (LEDs) based on red- and green-emitting lead halides. However, reducing the lead toxicity of emissive materials and achieving high-efficiency blue-emitting LED beads on lead-free metal halides remains a great challenge. Herein, lead-free zero-dimensional metal halides Cu:(PEA)2ZnX4 (X = Cl, Br) were developed to solve the above bottlenecks. Cu substitution enhanced the photoluminescence quantum yield (PLQY) of (PEA)2ZnBr4 from 3.4% to 55% and that of (PEA)2ZnCl4 from 2.7% to 34.5%. Interestingly, dual emission peaks are observed at low temperatures due to the presence of two excitation structures on the potential energy surface of the triplet state excited states. The self-trapped excitons of Cu:(PEA)2ZnBr4 can cross this potential barrier between the two triplet-state excited states by acquiring thermal energy, but Cu:(PEA)2ZnCl4 cannot overcome the barrier due to the different molecular environments. For the first time, using Cu:(PEA)2ZnX4 as the light-emitting layers, sky-blue LEDs with an external quantum efficiency (EQE) of 0.45% and 0.83% for Cu:(PEA)2ZnCl4 and Cu:(PEA)2ZnBr4 were obtained, demonstrating that broadband light-emitting lead-free metal halides have great potential for sky-blue light-emitting diode applications. [ABSTRACT FROM AUTHOR]

A convenient and ultrasensitive ratiometric fluorescent probe was innovatively developed for Hg(II) detection and trypsin activity evaluation based on carbon dots (CDs) and tetraphenylporphyrin tetrasulfonic acid (TPPS) using bovine serum albumin (BSA) as the substrate of trypsin. The ratiometric fluorescence signal arises from CDs (λem = 506 nm) and TPPS (λem = 645 nm) via an inner filter effect. Hg2+ can trigger the formation of TPPS-Mn2+ metalloporphyrin for target Hg2+ recycling amplification, while both TPPS-Hg2+ and TPPS-Mn2+ metalloporphyrins do not affect the fluorescence of CDs. Small amino acids and peptide fragments, which are the products of BSA under the digestion of trypsin, bind stronger with Hg2+ than with TPPS. The decomposition of both TPPS-Hg2+ and TPPS-Mn2+ metalloporphyrins leads to a variation in the ratiometric fluorescence signal. Under optimized conditions, this probe provided an inspiring detection limit of 0.086 nM for Hg2+ and 0.013 ng mL−1 for trypsin, which possessed acceptable sensitivity for Hg2+ detection and trypsin activity evaluation in authentic samples. This unprecedented CD-based ratiometric fluorescence proposal for ultrasensitive quantification of Hg2+ concentration and selective assessment of trypsin activity gives a new insight for designing metal ion assays or enzymatic activity bioassays under different enzymatic substrates in the near future. [ABSTRACT FROM AUTHOR]

MoS2-like layered 2D materials have attracted attention worldwide due to their intriguing material properties. In contrast, it is still a great challenge to prepare non-layered 2D materials that may provide unique electronic and optoelectronic properties compared to layered materials. As an emerging IIIA–VIA semiconductor, In2S3 shows great potential for application in optoelectronics. Herein, ultrathin non-layered In2S3 nanoflakes, with uniform thickness and lateral size reaching the sub-millimeter scale, are synthesized on mica substrates via a simple physical vapor epitaxy method. Then, a photodetector based on an In2S3/Si heterojunction is fabricated. Owing to the strong light–matter interactions of In2S3 and the built-in potential at the In2S3/Si interface, which accelerates the separation of photoexcited electron–hole pairs, the device exhibits a broadband sensitivity covering the visible to near-infrared region. The responsivity, detectivity and rise/decay time are 579.6 A W−1, 2 × 1011 Jones and 9/0.131 ms, respectively. These performance metrics are among the best values when compared with those of reported layered 2D materials/Si heterojunction photodetectors. Notably, the In2S3/Si photodetector suffers from negligible performance degradation even after 1050 cycles of operation or 6 months of exposure to air. These findings broaden the scope of 2D materials and highlight that In2S3 nanoflakes hold great potential for further optoelectronic applications. [ABSTRACT FROM AUTHOR]

Owing to their exciting electronic and optical attributes, layered materials have attracted great interest in the field of next-generation photodetectors. However, owing to their large dark current, low detectivity and small signal-to-noise ratio, the performance of photodetectors based merely on layered materials is unsatisfactory for use in weak signal detection. Integrating layered materials with mature silicon (Si) technology offers a feasible scenario to overcome these drawbacks. Herein, we report the facile synthesis of layered ZnIn2S4 nanosheets and the construction of a ZnIn2S4/Si heterostructure photodetector array for weak signal detection. Owing to the interfacial charge transfer, which significantly suppresses the dark current and accelerates the separation of the photoexcited electron–hole pairs, the fabricated ZnIn2S4/Si photodetector array presents an ultralow dark current (18 pA), superior signal-to-noise ratio (11 572), stable photoswitching and high detectivity (2 × 1012 Jones). Notably, the heterostructure device exhibits an outstanding weak signal detection capability, which has been successfully demonstrated using the detection of weak light sources including a cell phone screen, flashlight and lighter. These results demonstrate that the synergetic effect of layered materials and mature semiconductor technology shows great potential for application in next-generation optoelectronics. [ABSTRACT FROM AUTHOR]

Solar energy-driven seawater desalination is a facile, green, and low-cost strategy to address the energy and fresh water crisis. 2D layered alloy materials (2DLAMs) have aroused significant interest in this field due to their strong light–matter interaction, abundant intermediate band states, and superior stability. Herein, we demonstrated an efficient self-floating solar-enabled 2DLAM evaporator for the first time for seawater desalination. It is achieved by depositing layered BiInSe3 onto carbon foam (CF) via one-step pulsed-laser deposition. Importantly, the BiInSe3@CF device exhibits an evaporation rate of 1.1 kg m−2 h−1 upon 1 sun irradiation (1 sun = 100 mW cm−2), which is one of the highest values reported to date. In addition, ion concentrations of the resulting water decrease by four orders of magnitude, which are much lower than the upper limit of the drinking water standards of the World Health Organization and the US Environmental Protection Agency. Moreover, the device demonstrates good reusability with no observable degeneration in 15 cycles over a period of 15 days. This high-performance seawater desalination capability is attributed to the synergistic effect of excellent light absorption, abundant phonon-assisted decay, and superior localized interfacial heating. These findings suggest that the functional design of the floatable 2DLAM evaporator represents a convenient and efficient route to achieve high-quality seawater desalination. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) manifest excellent phonon-limited mobility and strong light–matter interaction, which, however, conflict with the long response time and low responsivity of TMD-based photodetectors. The extreme susceptibility of TMDs' electronic qualities to the large density of unscreened disturbances from the SiO2 substrate accounts for such inconformity. Here, we evaluated the potential of WS2 for photodetectors by passivating SiO2 substrates with layered Bi2Te3, a representative three dimensional topological insulator. Comparative photoswitching measurements of the WS2/Bi2Te3 photodetector demonstrated its stable and broadband photoresponse from 370 to 1550 nm. Meanwhile, WS2 and Bi2Te3 allied a high responsivity of 30.7 A W−1, a pronounced detectivity of 2.3 × 1011 cm Hz1/2 W−1 as well as a short response time of 20 ms, which make the device stand out among previously reported WS2 photodetectors. In fact, the responsivity and detectivity are comparable to those of state-of-the-art commercial Si and Ge photodetectors (R∼ 0.5 to 0.85 A W−1, D*∼ 3 × 1011 to 3 × 1012 cm Hz1/2 W−1), suggesting its great potential for practical applications. In addition, we also established that the excellent device performance is attributed to the synergy of the passivation of the SiO2 substrate, efficient carrier separation at the WS2/Bi2Te3 heterointerface and excellent carrier transport along the time-reversal-symmetry protected surface channel of Bi2Te3. In summary, these findings suggest that the WS2/Bi2Te3 photodetector will launch a significant advance in next-generation photodetection. Moreover, the interface engineering strategy depicts a universal scenario for development of TMD devices in the future. [ABSTRACT FROM AUTHOR]

In this study, cost-efficient atmospheric pressure chemical vapor deposition has been successfully developed to produce well-aligned high-quality monocrystalline Bi 2 S 3 nanowires. By virtue of surface strain-induced energy band reconstruction, the Bi 2 S 3 photodetectors demonstrate a broadband photoresponse across 370.6 to 1310 nm. Upon a gate voltage of 30 V, the responsivity, external quantum efficiency, and detectivity reach 23 760 A W -1 , 5.55 × 10 6 %, and 3.68 × 10 13 Jones, respectively. The outstanding photosensitivity is ascribed to the high-efficiency spacial separation of photocarriers, enabled by synergy of the axial built-in electric field and type-II band alignment, as well as the pronounced photogating effect. Moreover, a polarization-discriminating photoresponse has been unveiled. For the first time, the correlation between quantum confinement and dichroic ratio is systematically explored. The optoelectronic dichroism is established to be negatively correlated with the cross dimension ( i.e. , width and height) of the channel. Specifically, upon 405 nm illumination, the optimized dichroic ratio reaches 2.4, the highest value among the reported Bi 2 S 3 photodetectors. In the end, proof-of-concept multiplexing optical communications and broadband lensless polarimetric imaging have been implemented by exploiting the Bi 2 S 3 nanowire photodetectors as light-sensing functional units. This study develops a quantum tailoring strategy for tailoring the polarization properties of (quasi-)1D material photodetectors whilst depicting new horizons for the next-generation opto-electronics industry.

Two-dimensional (2D) magnetic materials are of wide research interest owing to their promising applications in spintronic devices. Among them, chromium chalcogenide compounds are some of the limited available systems that present both high stability in air and high Curie temperatures. Epitaxial growth techniques based on chemical vapour deposition (CVD) have been demonstrated to be a robust method for growing 2D non-layered chromium chalcogenides. However, the growth mechanism is not well-understood. Here, we demonstrate the epitaxial growth of Cr 3 Te 4 nanoplates with high quality on mica. Atomic-resolution scanning transmission electron microscopy (STEM) imaging reveals that the epitaxial growth is based on nanosized chromium oxide seed particles at the interface of Cr 3 Te 4 and mica. The chromium oxide nanoparticle exhibits a coherent interface with both mica and Cr 3 Te 4 with a lattice mismatch within 3%, suggesting that, as a buffer layer, chromium oxide can release the interfacial strain, and induce the growth of Cr 3 Te 4 although there is a distinct oxygen-content difference between mica and Cr 3 Te 4 . This work provides an experimental understanding behind the epitaxial growth of 2D magnetic materials at the atomic scale and facilitates the improvement of their growth procedures for devices with high crystalline quality., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two-dimensional (2D) material-based van der Waals (vdW) heterostructures with exotic semiconducting properties have shown tremendous potential in next-generation photovoltaic photodetectors. Nevertheless, these vdW heterostructure devices inevitably suffer from a compromise between high sensitivity and fast response. Herein, an ingenious photovoltaic photodetector based on a WSe 2 /WS 2 /p-Si dual-vdW heterojunction is demonstrated. First-principles calculations and energy band profiles consolidate that the photogating effect originating from the bottom vdW heterojunction not only strengthens the photovoltaic effect of the top vdW heterojunction, but also suppresses the recombination of photogenerated carriers. As a consequence, the separation of photogenerated carriers is facilitated and their lifetimes are extended, resulting in higher photoconductive gain. Coupled with these synergistic effects, this WSe 2 /WS 2 /p-Si device exhibits both high sensitivity (responsivity of 340 mA W -1 , a light on/off ratio greater than 2500, and a detectivity of 3.34 × 10 11 Jones) and fast response time (rise/decay time of 657/671 μs) under 405 nm light illumination in self-powered mode. Finally, high-resolution visible-light and near-infrared imaging capabilities are demonstrated by adopting this dual-heterojunction device as a single pixel, indicating its great application prospects in future optoelectronic systems., Competing Interests: The authors declare no competing financial interests., (This journal is © The Royal Society of Chemistry.)

Low light absorption and limited carrier lifetime are critical obstacles inhibiting further performance improvement of 2D layered material (2DLM) based photodetectors, while scalable fabrication is an ongoing challenge prior to commercialization from the lab to market. Herein, wafer-scale SnS/ZIS hierarchical nanofilms, where out-of-plane SnS (O-SnS) is modified onto in-plane ZIS (I-ZIS), have been achieved by pulsed-laser deposition. The derived O-SnS/I-ZIS photodetector exhibits markedly boosted sensitivity as compared to a pristine ZIS device. The synergy of multiple functionalities contributes to the dramatic improvement, including the pronounced light-trapping effect of O-SnS by multiple scattering, the high-efficiency spatial separation of photogenerated electron-hole pairs by a type-II staggered band alignment and the promoted carrier transport enabled by the tailored electronic structure of ZIS. Of note, the unique architecture of O-SnS/I-ZIS can considerably expedite the carrier dynamics, where O-SnS promotes the electron transfer from SnS to ZIS whilst the I-ZIS enables high-speed electron circulation. In addition, the interlayer transition enables the bridging of the effective optical window to telecommunication wavelengths. Moreover, monolithic integration of arrayed devices with satisfactory device-to-device variability has been encompassed and a proof-of-concept imaging application is demonstrated. On the whole, this study depicts a fascinating functional coupling architecture toward implementing chip-scale integrated optoelectronics.