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With their fascinating properties, emerging two-dimensional (2D) materials offer innovative ways to prepare high-performance infrared (IR) detectors. However, the current performance of 2D IR photodetectors is still below the requirements for practical application owing to the severe interfacial recombination, sharply raised contact resistance, and deteriorated metal conductivity at nanoscale. Here, we introduce a vertical barrier heterojunction with a structure of PtSe2/GaAs that combines the excellent optoelectronic properties of transition metal sulfides with topological semi-metals, which allows for an adjustable bandgap and high carrier mobility. The heterojunction was fabricated using the wet transfer method. The heterostructures show significant rectification behaviors and photovoltaic effects, which allow it to operate as a self-driven photodetector at zero bias. The photoresponse parameters at 850 nm with zero bias voltage are 67.2 mA W–1, 6.7 × 1012Jones, 9.8%, 3.8 × 105, 164 μs, and 198 μs for the responsivity, specific detectivity, external quantum efficiency, Ilight/Idarkratio, rise time, and fall time, respectively. Moreover, the heterojunction is highly sensitive to a wide spectral band from ultraviolet to near-infrared (360–1550 nm). At the same time, this heterostructure demonstrates significant potential for applications in IR polarized light detection and room-temperature high-resolution IR imaging. The excellent properties of the heterojunction make it well-suited for high-performance, self-powered IR detection.

PtSe2has received extensive research attention in infrared (IR) detection owing to its tunable bandgap, high carrier mobility and efficient optical absorption. However, traditional preparation methods are characterized by complicated growth conditions, lengthy processing times, limited Pt and Se source selectivity, subpar crystal quality, and challenges in large-scale fabrication, which impede their practical applications. Here, a convenient magnetron co-sputtering method was employed to fabricate large-area, high-quality PtSe2films. The characterizations of the phase, microstructure, morphology and films grown at different temperatures reveal good crystallinity, controllability, homogeneity, flat surface morphology, narrow bandgap and excellent IR absorption of the PtSe2films. Furthermore, we investigated the optimal substrates and growth temperatures. The PtSe2-based photodetectors show fast response time and reasonable responsivity. The short preparation time demonstrates the potential for large-scale applications of PtSe2in next generation IR detection systems compatible with established Si technologies.

Among the two-dimensional (2D) Bi2O2X (X = S, Se, and Te) series, Bi2O2Te has the smallest effective mass and the highest carrier mobility. However, Bi2O2Te has rarely been investigated, most likely due to the lack of feasible methods to synthesize 2D Bi2O2Te. Herein, 2D Bi2O2Te nanosheets are successfully synthesized by low-temperature oxidation of Bi2Te3nanosheets synthesized using a solvothermal method. The performance of a quasi-solid-state photoelectrochemical-type (PEC-type) photodetector based on 2D Bi2O2Te nanosheets is systematically investigated. Remarkably, the device has a high responsivity of 20.5 mA W−1(zero bias) and fast rise/fall times of 6/90 ms under 365 nm illumination, which is superior to the majority of PEC-type photodetectors based on bismuth-based compounds. More importantly, due to the strong anisotropy of 2D Bi2O2Te nanosheets, the device achieves a dichroic ratio as high as 52, which belongs to the state-of-the-art polarized photodetectors. Besides, the capacity of 2D Bi2O2Te for high-resolution polarization imaging is demonstrated. This work provides a promising strategy for the synthesis of 2D Bi2O2Te nanosheets to fabricate a high-performance and polarization-sensitive photodetector.

• A facile, environmentally friendly, and low-cost solvothermal route is proposed to synthesize high-quality single crystal bismuth nanoparticles. • The photodetection performance of bismuth nanoparticles has been systematically investigated for the first time. • Bismuth nanoparticles PEC-type photodetector exhibits self-powered and UV–Vis-NIR broadband photodetection properties. • A high responsivity of 4.979 mA/W is achieved under the light illumination at a wavelength of 405 nm without bias, accompanied with a fast response speed (tr ≤ 12 ms, td ≤ 46 ms). • The working mechanism of the bismuth nanoparticles PEC-type photodetector is proposed. Bismuth, an emerging topological insulator, has attracted great interest due to its fascinating properties. Herein, a facile, environmentally friendly, and low-cost solvothermal route was proposed to synthesize high-quality single-crystal bismuth nanoparticles. The performance of bismuth nanoparticles photoelectrochemical-type photodetector has been systematically evaluated. The responsivity spectrum shows that the bismuth nanoparticles photodetector has a broad response range from ultraviolet (UV) to near-infrared (NIR), with the highest responsivity of 4.979 mA/W at a wavelength of 405 nm without bias. Additionally, the device exhibits a fast response speed (t r < 12 ms, t d < 46 ms) and a high specific detectivity (3.71 × 1010 Jones). These results indicate that bismuth nanoparticles have great potential in the application of self-powered broadband photodetectors with high responsivity. Moreover, the working mechanism of bismuth nanoparticles photodetector was proposed. [ABSTRACT FROM AUTHOR]

The hybrid 2D/3D heterostructure, which synergistically combine the high surface area and superior surface properties of 2D materials with the volumetric advantages and mechanical stability of 3D materials, offer an efficient and unique platform for electronic, optoelectronic, and energy conversion applications. Although this structure offers numerous advantages, optimizing the performance of 2D/3D heterojunction devices still faces challenges such as interface control difficulty, doping uniformity, and scalability for mass production. To simplify and effectively optimize the performance of 2D/3D heterojunction devices, this study delves into the impact of the thickness of 2D Bi2Se3films on the performance of Bi2Se3/GaN heterojunction photodetectors. In thinner Bi2Se3films, a higher surface defect density increases carrier recombination efficiency, while in thicker films, an increase in internal defects impedes carrier transport. Our findings reveal an optimal film thickness that balances surface and internal defects, enhancing carrier dynamics and device performance. Remarkably, the Bi2Se3(14.8 nm)/GaN heterojunction detector exhibits superior broadband response from ultraviolet to near-infrared, with a maximum responsivity of 0.07 A/W, a detectivity of 1.79 × 1012Jones, and an on/off ratio of 1.02 × 104. Additionally, the device demonstrates prolonged stability in response and multispectral imaging capability. This research not only underscores the critical role of film thickness in modulating device performance but also provides novel theoretical and practical guidance for designing high-performance, self-powered, broadband heterojunction photodetectors, offering significant implications for scientific research and practical applications.

ZnO/ZnS/CuS net‐like nanosheet (NS) heterojunction array was fabricated via a simple solution method at a low temperature. Morphology and structure of ZnO/ZnS/CuS NS were characterized by scanning electron microscope (SEM) and Transmission electron microscope (TEM). With tiny particles attaching on the rough surface, the thin ZnO/ZnS/CuS NS grew vertically and arranged regularly on Al substrate, providing large effective illumination area and massive active sites. Elemental composition and valence state were confirmed with energy dispersive X‐ray spectrometry and X‐ray photoelectron spectroscopy (XPS), respectively. The UV–vis absorbance spectra indicated that the absorption range of ZnO NS was expanded to the visible region effectively, and the original absorption intensity in the ultraviolet region was also improved after being coated with ZnS and CuS. Photocatalytic activity tests of ZnO, ZnO/ZnS, and ZnO/ZnS/CuS NS were carried out with methyl orange as a simulated pollutant, in which ZnO/ZnS/CuS heterojunction showed great enhancement when making comparison with pure ZnO and ZnO/ZnS NS. After five reuse cycles, photocatalytic performance could still be maintained well, indicating the good catalytic stability. Finally, a probable photocatalytic mechanism was also discussed. The ZnO/ZnS/CuSnet‐like nanosheet array was fabricated with simple solution method at a low temperature. Not only the ternary structure owns a wide absorption range, but also the stepped energy band can effectively separate photo‐generated carriers, which are helpful to improve the photocatalytic efficiency

Hydrangea‐like ZnO nanospheres were fabricated on Al substrates via a facile hydrothermal method with only one step. Scanning electron microscopy, energy‐dispersive spectroscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, and photoluminescence were used to investigate their morphology, component, structure, and optical properties. The hierarchical nanospheres are fabricated by 2D nanosheets with the shape of 3D sphere. By adjusting the reaction time, the formation process was monitored. The photocatalytic activity of ZnO nanospheres was also investigated for their dye degradation, and they exhibit good photocatalytic ability to congo red, with the degradation rate of 98.4%. Besides, they have universal catalysis effect on methyl orange. Hierarchical ZnO nanospheres were synthesized on Al substrates with only one step via hydrothermal method. Fabricated by 2D nanosheets with the shape of 3D sphere, they have a high contact area with pollutant solution and exhibit good photocatalytic ability to congo red and methyl orange. The absorption around the visible light range leads to enhanced photocatalytic ability, caused by numerous defect energy levels.

Photodetectors with a broad-band response range are widely used in many fields and are regarded as pivotal components of the modern miniaturized electronics industry. However, commercial broad-band photodetectors composed of traditional bulk semiconductor materials are still limited by complex preparation techniques, high costs, and a lack of mechanical strength and flexibility, which are difficult to satisfy the increasing demand for flexible and wearable optoelectronics. Therefore, researchers have been devoted to finding new strategies to obtain flexible, stable, and high-performance broad-band photodetectors. In this work, a novel self-assembled BiGaSeAs composite superlattice-structured nanowire was developed with a simple chemical vapor deposition method for easy fabrication. After the device assembling, the photodetector showed outstanding performance in terms of obvious Ion/Ioff(13.9), broad-band photoresponse (365–940 nm), excellent responsivity (1007.67 A/W), high detectivity (9.38 × 109Jones), and rapid response (21 and 23 ms). The formation of microheterojunctions among various materials inside the nanowires also contributed to their extended broad-spectrum response and outstanding detection ability. These results indicate that the BiGaSeAs nanowires have potential applications in the field of flexible and wearable electronics.

Gallium oxide thin films were deposited by radio frequency magnetron sputtering technique. Structural, optical and photoelectrical properties of Ga2O3 thin films were investigated in detail. The as-grown Ga2O3 thin films were amorphous, while those annealed film were polycrystalline with monoclinic structure. Amorphous and polycrystalline gallium oxide metal-semiconductor-metal photodetectors were fabricated. However, annealed polycrystalline films have no photoresponse for deep ultraviolet light. The responsivity of the photodetector based on as-grown amorphous film is 122.7 uA/W at 256 nm and the ultraviolet (UV)-to-visible rejection ratios were 100, which indicates that the amorphous Ga2O3 thin films have potential application for solar-blind photodetector. High concentration of oxygen vacancies of amorphous film are considered to be responsible for photoresponse in amorphous gallium oxide thin films.

In our work, (InxGa1-x)2O3 films were obtained on sapphire (0001) substrates by radio frequency magnetron sputtering. The influence of annealing temperature on crystalline structure, morphology, transmittance, and the optical band gap was investigated in detail. X-ray diffraction analysis showed that the as-prepared (InxGa1-x)2O3 film was amorphous and the crystal quality was improved with the increasing of annealing temperature. The peak shifted to larger angle with the increasing of annealing temperature. Energy Dispersive Spectrometer analysis showed decreasing trend of In content. X-ray diffraction analysis and Energy Dispersive Spectrometer jointly indicated the peak shift due to the decreasing of In content and variation of tensile stress. The morphology feature of films was investigated by atomic force microscope. The island structure existed in the surface of films at the annealing temperature from 500degC to 900degC and when annealing temperature is 1000degC, islands disappeared and needle-like structure occurred. Transmittance spectra revealed excellence optical properties of films and absorption coefficient spectra showed the decreasing of band gaps of films with the increasing of annealing temperature. It could be attributed to the decreasing of In content and variation of tensile stress.

The construction of heterojunction photocatalysts is an effective method to improve photocatalytic efficiency since the potential gradient and built-in electron field established at the junction could enhance the efficiency of charge separation and interfacial charge transfer. Nevertheless, heterojunction photocatalysts with strong built-in electron fields remain difficult to build since the two adjacent constitutes must be satisfied with an appropriate band alignment, redox potential, and carrier concentration gradient. Here, an efficient charge transfer-induced doping strategy is proposed to enhance the heterojunction built-in electron field for stable and efficient photocatalytic performance. Carrier transfer tests show that the rectification ratio of the n-TiO2–X/n-BiOI heterojunction is significantly enhanced after being coated with graphene oxide (GO). Consequently, both the hydrogen production and photodegradation performance of the GO composite heterojunction are considerably enhanced compared with pure TiO2–X, BiOI, and n-TiO2–X/n-BiOI. This work provides a facile method to prepare heterojunction photocatalysts with a high catalytic activity.

Vertically aligned rutile TiO2nanowire arrays (NWAs) with lengths of ∼44 μm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2NWA based DSCs so far.

The effect of air and oxygen annealing on the structural and the optical properties of hydrothermally synthesized ZnO nanorods was investigated. After hydrothermal synthesis, the resulting ZnO nanorods were annealed in air and under an oxygen atmosphere at 370°C for 1 h. X-ray diffraction results revealed that the oxygen-annealed nanorods possessed high crystallinity with a hexagonal-wurtzite crystal structure in the (002) plane. Evaluation of strain showed a tensile lattice strain of 0.426% resulting from oxygen annealing. The photoluminescence measurements showed that the relative intensity ratio of the near-band-edge emission (NBE) to the green emission (INBE/IGE) increased from ~2.6 for the as-grown ZnO nanorods to ~68.7 when the nanorods were annealed under oxygen. After annealing, a red shift of ~30 and ~44 meV in the NBE was observed for the nanorods that were annealed in air and under oxygen, respectively. This shift is attributed to the interaction between the neutral acceptors and the adsorbed oxygen atoms.

The effect of indium cluster on enhanced ultraviolet luminescence in AlxInyGa1–x–yN quaternary alloys with increasing Al composition was investigated. X-ray diffraction (XRD), temperature-dependent photoluminescence (PL), transmittance spectra, and Raman scattering measurements have been employed to study the AlxInyGa1–x–yN quaternary alloy. Abnormal S-shaped temperature dependence of PL emissions in high Al content sample originated from carrier localization induced by indium nanoclusters, which is in good agreement with the pure InN mode measured by Raman scattering. A large Stokes shift between the emission peak and the absorption edge is also found in the high Al content sample. All these observations suggested that the enhancement of carrier localization by indium nanoclusters is responsible for the increase in radiative recombination probability with increasing Al composition. Our results demonstrated that AlxInyGa1–x–yN quaternary alloy can exhibit a larger band gap than that of GaN and enhanced ultraviolet luminescence due to the existence of indium nanoclusters. Meanwhile, the effect of indium clusters was increased with Al compositions increasing, even at low indium mole fraction about 4%.

We investigated the cryogenic photoluminescence process of MAPbBr3single crystal from 10 K to 120 K. The PL spectra can be fitted by Gauss functions perfectly, and the free excitons as well as bound excitons emission coexist. During the cryogenic recombination process, the exciton localization effect and the thermal effect both react on the MAPbBr3single crystal. From 10 K to 55 K, the localization effect is dominant due to the lower temperature, the excitons are inclined to migrate toward lower energy sites and cause the red-shift with narrow widths. Simultaneously, the localization effect tends to weaken with the temperature increasing, and the intensities gradually enhance. From 55 K to 120 K, the thermal effect becomes stronger than the localization effect, and becomes the dominant factor. Due to the thermal quenching effect and multi-broadening mechanism, all emissions present lower intensities and wider profile. Meanwhile, the thermal expansion of crystal lattice contributes to the emission blue-shift. The competition between exciton localization effect and thermal effect determines the PL non-monotonic variation of the MAPbBr3single crystal in the cryogenic process.

In our work, (InxGa1-x)2O3films were obtained on sapphire (0001) substrates by radio frequency magnetron sputtering. The influence of annealing temperature on crystalline structure, morphology, transmittance, and the optical band gap was investigated in detail. X-ray diffraction analysis showed that the as-prepared (InxGa1-x)2O3film was amorphous and the crystal quality was improved with the increasing of annealing temperature. The (4¯02)peak shifted to larger angle with the increasing of annealing temperature. Energy Dispersive Spectrometer analysis showed decreasing trend of In content. X-ray diffraction analysis and Energy Dispersive Spectrometer jointly indicated the peak shift due to the decreasing of In content and variation of tensile stress. The morphology feature of films was investigated by atomic force microscope. The island structure existed in the surface of films at the annealing temperature from 500°C to 900°C and when annealing temperature is 1000°C, islands disappeared and needle-like structure occurred. Transmittance spectra revealed excellence optical properties of films and absorption coefficient spectra showed the decreasing of band gaps of films with the increasing of annealing temperature. It could be attributed to the decreasing of In content and variation of tensile stress.

Gallium oxide thin films were deposited by radio frequency magnetron sputtering technique. Structural, optical and photoelectrical properties of Ga2O3thin films were investigated in detail. The as-grown Ga2O3thin films were amorphous, while those annealed film were polycrystalline with monoclinic structure. Amorphous and polycrystalline gallium oxide metal-semiconductor-metal photodetectors were fabricated. However, annealed polycrystalline films have no photoresponse for deep ultraviolet light. The responsivity of the photodetector based on as-grown amorphous film is 122.7 μA/W at 256 nm and the ultraviolet (UV)-to-visible rejection ratios were 100, which indicates that the amorphous Ga2O3thin films have potential application for solar-blind photodetector. High concentration of oxygen vacancies of amorphous film are considered to be responsible for photoresponse in amorphous gallium oxide thin films.

Phosphorus‐doped ZnO nanorods were successfully prepared by hydrothermal method using ammonium dihydrogen phosphate as the dopant source. The effects of different Zn sources, zinc nitrate concentration, reaction duration, ammonium dihydrogen phosphate concentration, and annealing temperature on the morphologies and phosphorus content of ZnO nanorods were investigated. The doping mechanism of phosphorus‐doped ZnO nanorods has been discussed. Detailed photoluminescence studies of phosphorus‐doped ZnO revealed characteristic phosphorus acceptor‐related peaks: neutral acceptor‐bound exciton emission at 3.347 eV, and donor‐to‐acceptor pair emission at 3.232 eV, free‐electron to neutral‐acceptor emission at 3.312 eV. This means that stable acceptor levels with a binding energy of about 126 meV were formed by phosphorus doping. The effects of different Zn sources, zinc nitrate concentration,reaction duration, ammonium dihydrogen phosphate concentration, and annealing temperature on the morphologies and phosphorus content of ZnO nanorods were investigated. The doping mechanism of phosphorus doped ZnO nanorods has been discussed