Photoelectric Performance Test Research Articles

The Influence of Temperature on the Photoelectric Properties of GeSe Nanowires.

Using physical vapor deposition (PVD) technology, GeSe nanowires were successfully fabricated by heating GeSe powder at temperatures of 500 °C, 530 °C, 560 °C, 590 °C, and 620 °C. The microstructure, crystal morphology, and chemical composition of the resulting materials were thoroughly analyzed employing methods like Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), plus Raman Spectroscopy. Through a series of photoelectric performance tests, it was discovered that the GeSe nanowires prepared at 560 °C exhibited superior properties. These nanowires not only possessed high crystalline quality but also featured uniform diameters, demonstrating excellent consistency. Under illumination at 780 nm, the GeSe nanowires prepared at this temperature showed higher dark current, photocurrent, and photoresponsivity compared to samples prepared at other temperatures. These results indicate that GeSe nanomaterials hold substantial potential in the field of photodetection. Particularly in the visible light spectrum, GeSe nanomaterials exhibit outstanding light absorption capabilities and photoresponse.

Ga doped TiO2 with enhanced photocatalytic degradation performance benefited from rich oxygen vacancies

Titanium dioxide (TiO2) is widely regarded as one of the most promising semiconductors among the various photocatalytic materials. In this demonstration, Ga-doped TiO2 with rich oxygen vacancies (OVs) was synthesized by a sol–gel method. Systematic characterization provides soild attest for the successful doping of Ga and the enhancement level of OVs. The large specific surface area provides richer surface-active sites for Ga/OVs-TiO2 samples through BET test. The photoelectric performance test shows that Ga doping and the existence of rich OVs can effectively improve the photogenerated carriers separation and migration efficiency of TiO2. The degradation results for rhodamine B (RhB) and tetracycline hydrochloride (TC) attest that the photocatalytic efficiency of Ga-doped TiO2 is better than that of the reference TiO2. The capture experiment further exhibits that hydroxyl radical and superoxide radical are the main active species in photocatalytic degradation. The synergistic effect of Ga doping and OVs significantly improves the separation and migration of photogenerated carriers, therefore boosting the photocatalytic performance. This work provides a reliable guide for utilization of Ga and a solid strategy of element doping to improve the photocatalytic performance of TiO2.

Effect of TiO2 nanoparticle load on photoelectric properties of TiO2/VGs heterojunction

Preparation of Titanium dioxides loaded vertical graphene nanosheets (TiO2/VGs) composite films with heterojunctions by a multi-plasma combination method. Highly vertically oriented VGs were prepared by helicon wave plasma chemical vapor deposition (HWP-CVD), and TiO2 nanoparticles were deposited on VGs templates by ultra-high vacuum magnetron sputtering (UH-MS). By controlling the sputtering time of TiO2 nanoparticles to modulate the nanoparticle loading content. The morphology, structure, and photocatalytic performance of heterojunction TiO2/VGs composite films were investigated. The characterization results of morphology and structure show that the structure of VGs nanosheets is not altered by the increase of the deposited particle content, indicating that VGs have excellent mechanical properties as a template for TiO2 loading. As the deposition time of the TiO2 nanoparticles increases, the loading type progresses from epitaxial growth at the beginning to conformal deposition and eventually to gap-filling growth. Photoelectric performance tests showed that the heterojunctions were formed at the interface between TiO2 and VGs. The photovoltage test results show that the photogenerated carriers are effectively separated at the interface, and the nanosheets can promote the migration of separated electrons to the external circuit. The variation in photocurrent density shows a positive correlation with the number of TiO2 attachment sites and loading content on the surface of the VGs nanosheets.

Improved optoelectronic performance from the internal secondary excitation of MAPbCl3-MAPbBr3 single crystal photodetectors

Single crystal (SC) MAPbBr 3 and MAPbCl 3 perovskite are considered promising materials for fabricating high-performance photodetectors (PDs) due to their impressive optoelectronic properties and good chemical stability. Structural modification of PDs is the fundamental solution to improve performance. In this paper, we designed a simple structure diagram considering photoelectric properties and the possibility of epitaxial crystal growth. Then a solution height restriction method (SHR) was used to grow the crystal and make the internal secondary excitation feasible. X-ray rocking curves (XRC) of MAPbBr 3 -SHR SCs show the quality of crystal under this growth method is excellent. X-ray photoelectron spectroscopy (XPS) measurements and Energy-dispersive X-ray spectroscopy (EDS) indicate element diffusion exists in the interface. Photoluminescence spectra (PL) and the photoelectric performance test have proved the existence and validity of the internal secondary excitation of crystals. Based on the above analysis, it was demonstrated that the inner MAPbCl 3 single-crystal enhances the optoelectronic performance of MAPbCl 3 -MAPbBr 3 crystals by the internal secondary excitation effect.

Synergetic effect of cobalt phosphide cocatalyst modified molybdenum disulfide for boosting photocatalytic performance

BackgroundMolybdenum disulfide (MoS2) has received extensive attention in environmental remediation due to its unique two-dimensional lamellar structure and high specific area. To further improve the photocatalytic performance of MoS2, supported co-catalysts have been proven to be one of the effective modification measures. MethodsThe composite photocatalyst CoP/MoS2 was prepared by a facile self-assembly method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful loading of CoP onto the MoS2 surface. The UV-vis results showed that the MoS2 modified by CoP had enhanced absorption capacity for visible light. The photoelectric performance test showed that the synergistic effect of CoP and MoS2 promoted the charge transfer between them and reduced the charge recombination rate. Significant findingsThe CoP/MoS2 composite photocatalyst exhibits a high degradation rate under visible light irradiation. The degradation rate of MBT can reach 97.2% within 80 min, which is 1.6 times that of the original MoS2 photocatalyst. This is mainly due to the efficient charge separation and synergistic effect of CoP and MoS2. The possible decomposition intermediates, photocatalytic pathways and mechanisms are also proposed. This work provides a valuable strategy for developing other semiconductors as co-catalysts to modify MoS2 for efficient photocatalytic applications.

The photodegradation property and mechanism of tetracycline by persulfate radical activated In2O3@LDHs Z−scheme heterojunction

Z − scheme heterojunctions can increase the electron transfer rate, inhibit the recombination of electrons and holes, and enable the material to possess a more vital redox ability. In this work, In2O3@ZnCr − LDHs Z − scheme heterojunction was fabricated by complexing ZnCr layered double hydroxides (LDHs) nanosheets on ho llow In2O3 nanorods and used for photocatalytic degradation of tetracycline (TC), a typical antibiotic. Under the optimal conditions of 0.6 g/L In2O3@ZnCr − LDHs, pH of 9, and reaction temperature of 40 °C, it takes 150 min for the degradation rate of TC to reach 87 %. With the addition of persulphate (PS) to form advanced oxidation processes (AOPs), the TC removal rate reached 83 % within 45 mins, and improvement was evident. When adding persulfate (PS) to form advanced oxidation processes (AOPs), the removal of TC reached 83 % within 45 min, and the improvement effect was pronounced. XPS, ESR, photoelectric performance test and DFT calculations show that the excellent photocatalytic activity is attributed to the built-in electric field in the direct Z − scheme heterojunction, which can boost the transfer of photogenerated carriers and reduce the recombination of electron-hole pairs. In addition, the heterojunction can photo-activate PS to generate more oxidative sulfate radicals, which has a synergistic effect with hydroxyl radical and superoxide radical to degrade TC. Therefore, the Z − scheme/PS − AOPs system has a potential application in antibiotic contaminant degradation.

Improved Interfacial Contact for Pyramidal Texturing of Silicon Heterojunction Solar Cells.

Reducing the surface reflectivity of silicon substrates is essential for preparing high-performance Si-based solar cells. We synthesized pyramid-nanowire-structured Si (Si-PNWs) anti-reflection substrates, which have excellent light-trapping ability (<4% reflectance). Furthermore, diethyl phthalate (DEP), a water-insoluble phthalic acid ester, was applied to optimize the Si-PNWs/PEDOT:PSS interface; the photoelectric conversion efficiency of heterojunction solar cells was shown to increase from 9.82% to 13.48%. We performed a detailed examination of the shape and optical characteristics of Si-PNWs, as well as associated photoelectric performance tests, to investigate the origin of performance improvements in Si-PNWs/PEDOT:PSS heterojunction solar cells (HSCs).

Electrochemical Preparation of ZnO/PEDOT‐Type Conducting Polymers Composites for Ultraviolet Photodetector

AbstractGenerally, the ultraviolet photodetector devices based on ZnO/PEDOT composites were fabricated by spin coating of PEDOT solutions on ZnO nanorods array, which needs the polymer disperesed in solvent. In this paper, an electrochemical deposition method was proposed for the prepparation of ZnO/PEDOT‐type conducting polymers composites for ultraviolet photodetector. The poly(3,4‐proplene‐dioxythiophene) (PProDOT) and poly(3,4‐ethylenedioxy‐thiophene)(PEDOT) were selected as PEDOT‐type conducting polymers. The structure of composite materials was characterized by UV‐vis, XRD, Raman, SEM,EDS and XPS analysis. The effects of different polymers on the UV sensing ability of ZnO nanorods were studied. The structural results showed that the composites were successfully prepared by electrochemical deposition method indicating that the electrochecmial method was an effective way to prepraration of this type composites.The photoelectric performance test showed that the structure of the polymer chain affected the responsiveness of the materials, and the response time of ZnO/PProDOT was 14 s shorter than that of ZnO/PEDOT, and it displayed an excellent long‐term stability. After deposition of PProDOT, the UV responsivity of ZnO nanorods was increased from 2.5 A W−1 to 27.5 A W−1, and the external quantum efficiency and detectivity were significantly improved, implying that the PProDOT can be ideal candidate material for ultraviolet photodetector.

A novel high-efficiency photocatalyst Ta2O5/PtCl2 nanosheets for benzotriazole degradation

As a new type of organic pollutant, benzotriazole seriously threatens the ecological environment and human health. In recent years, semiconductor photocatalytic technology has been widely used in the field of photocatalytic degradation of organic pollutants, but there are still few studies on the degradation of benzotriazole, and the degradation efficiency needs to be improved. In this paper, PtCl2 was applied in the field of photocatalysis for the first time, and it was loaded on Ta2O5 nanosheets to prepared a novel heterojunction photocatalyst Ta2O5/PtCl2 nanosheets by chemical vapor deposition method. The study found that Ta2O5/PtCl2 nanosheets has excellent visible light absorption capacity due to its local surface plasma resonance (LSPR) effect. Ta2O5/PtCl2 nanosheets achieves the best degradation effect when the mass ratio of Ta2O5 and PtCl2 is 1:1, it can remove about 99% of rhodamine B (5 mg/L) in 30 min and 94% of benzotriazole (10 mg/L) in 120 min, and corresponding apparent first-order kinetic constants are 1.06 * 10−1 (min−1) and 2.11 * 10−2 (min−1), respectively. Moreover, the photocatalytic degradation results are also supported by the photoelectric performance test. Finally, the electrons transfer process and mechanism of photocatalytic degradation of organic pollutants are also speculated. These studies provide new design ideas for the preparation of new heterojunction photocatalysts, which have broad research and development prospects.

Depositing Ag2S quantum dots as electron mediators in SnS2/g-C3N4 nanosheet composites for constructing Z-scheme heterojunction with enhanced photocatalytic performance

The novel Z-scheme heterojunction photocatalyst g-C3N4/Ag2S/SnS2 with Ag2S quantum dots as electron mediators was successfully synthesized by in-situ ion exchange reaction and self-peeling of g-C3N4. Compared with g-C3N4, SnS2 or g-C3N4/SnS2, the photocatalyst g-C3N4/Ag2S/SnS2 exhibited more excellent photocatalytic performance under visible light irradiation. The removal rate of methyl orange was 96.8% after 30 minutes visible light irradiation and the reaction rate constant reached 0.10225 min-1. The enhanced photocatalytic activity could be attributed to the formation of Z-scheme heterojunction structure and the 2D layered structure. The electrochemical and photoelectric performance tests showed that the separation and transfer efficiency of the photogenic electron-hole pairs as well as the redox potential were significantly improved. Additionally, the quenching experiments showed that the superoxide radicals and holes were the primarily active species. Combined with other characterizations, the reaction mechanism of the g-C3N4/Ag2S/SnS2 for degrading the target pollutant methyl orange under visible light irradiation was proposed.

In situ synthesis of cobalt triphosphate on carbon paper for efficient electrocatalyst in dye-sensitized solar cell

The cobalt triphosphide (CoP3) was grew on carbon paper (CP) by using a hydrothermal method and served as counter electrode (CE) catalyst in dye-sensitized solar cells (DSSCs). The morphology of the CoP3/CP CE exhibits a regular fibrous structure, which provides a guarantee for its good electrochemical performance of the CE made from the cyclic voltammetry, Tafel test, etc. Various photoelectric performance tests also show that the DSSCs with CoP3/CP CE achieves good photoelectric conversion efficiency of 6.84% under 100 mW·cm−2 illumination, which can compare to that of the DSSC assembled with the Pt (6.79%) CE. Metal phosphides are rarely used as CEs in DSSCs, and they will have a good promising alternative to the Pt electrode in the future.

Pd nanoparticle size effects in localized surface plasmon-enhanced diamond photodetectors

Localized surface plasmon-enhanced diamond UV photodetectors with different diameters of Pd nanoparticles (NPs) had been successfully fabricated. Four Pd NPs with diameters of 20, 40, 60, 70 nm were deposited on diamond surfaces, respectively, and their height was 20 nm. Ti/Ni/Au metal electrodes were patterned on samples surfaces to form UV photodetectors. According to photoelectric performance test results, responsivities were enhanced with sizes of particles increasing at UV region, and diamond photodetector with 40 nm NPs showed the highest photocurrent-to-dark current ratio and UV-to-visible rejection ratio. Compared with pure diamond photodetectors, the responsivity and UV/visible rejection ratio Pd modified detectors can improve up to 3250 and 34 times, respectively. Plasmonic scattering effect was used to explain this phenomenon, and it is further confirmed by the simulated scattering cross-section.

Investigations of the Thermoelectric-Photoelectric Integrated Power Generator With I-Shaped Thermocouple Structure and its Test Structures

This work proposes the investigations of the thermoelectric-photoelectric integrated power generator with I-shaped thermocouple structure and its test structures. Integrated generator material parameters include resistivity, contact resistance, and Seebeck coefficient. They have a significant impact on the performance of thermoelectric devices. Output power per area reflects the thermoelectric performance of the polysilicon. In order to analyze the error of the test results, we designed the corresponding material parameter test structures to characterize the resistivity, contact resistance, and Seebeck coefficient of polysilicon. The maximum power factor of the thermoelectric output is $1.14\times 10^{-2} \,\, \mu $ Wcm−2K−2 in simulation. In the thermoelectric performance test, the maximum power factor is $7.81\times 10^{-3} \,\, \mu $ Wcm−2K−2. It is lower than the simulation. By analysis of the simulation and experiment of the test structure, the error is caused by fabrication error. In the photoelectric performance test, the open-circuit voltage of the integrated generator is 0.552 V. The short circuit current of the integrated generator is 4.32 mA.

Performance of WO3/g-C3N4 heterojunction composite boosting with NiS for photocatalytic hydrogen evolution

Carbon nitride, which is an intriguing photocatalyst but subjected to low surface area and rapid charge recombination, is used to produce H2 under the condition of visible-light. Here, we came up with a straightforward efficient approach to boost the hydrogen production performance of g-C3N4 for the first time, namely, the H2 production performance of the NiS/WO3/g-C3N4 synthetic was greatly enhanced approximately 8.9 multiples higher than that of pristine g-C3N4. The electronic structure and carrier behaviors of g-C3N4 are modified by a strategy of in-situ growth of NiS-WO3 assisted by NiS. The NiS-assisted WO3/g-C3N4 heterojunction system provides more active sites for the formation of heterojunction system which could promote charge separate and transfer efficiently. The photocatalytic hydrogen production rate of NiS which was used as a cocatalyst, was greatly increased in the hydrogen evolution reaction when added photocatalyst into the system, reaching 2929.1 μmol g−1 h−1 below the radiation of optical light. The improvement of photocatalytic performance can be owed to two aspects. First of all, the heterojunction formed by WO3/g-C3N4 can efficiently suppress the recombination of photogenerated electrons and holes. In addition, the presentation of NiS improves the electron mobility rate and provides more active sites for hydrogen evolution, which are proved with a succession of studies like XRD, FT-IR, TEM, SEM, BET, UV–vis DRS, XPS, photoelectric performance test and steady state/transient fluorescence. This work provides a hopeful approach for improving the property of g-C3N4 from the perspective of electronic structure and carrier behavioral regulation. At the same time, it provides new insights for hydrogen evolution of g-C3N4 heterojunction composites.

Fabrication of ZnO@Ag3PO4 Core-Shell Nanocomposite Arrays as Photoanodes and Their Photoelectric Properties.

In this study, we combine the methods of magnetron sputtering, hydrothermal growth, and stepwise deposition to prepare novel ZnO@Ag3PO4 core-shell nanocomposite arrays structure. Through scanning electron microscope (SEM) topography test, energy dispersive spectrometer (EDS) element test and X-ray diffractometry (XRD) component test, we characterize the morphology, element distribution and structural characteristics of ZnO@Ag3PO4 core-shell nanocomposite arrays structure. At the same time, we test the samples for light reflectance, hydrophilicity and photoelectric performance. We find that after deposition of Ag3PO4 on ZnO nanorods, light reflectance decreases. As the time of depositions increases, light reflectance gradually decreases. After the deposition of Ag3PO4, the surface of the sample shows super hydrophilicity, which is beneficial for the photoelectric performance test. Through the optical transient response test, we find that the photo-generated current reaches a maximum when a small amount of Ag3PO4 is deposited. As the time of depositions of Ag3PO4 increases, the photogenerated current gradually decreases. Finally, we conducted an alternating current (AC) impedance test and also verified the correctness of the photocurrent test. Therefore, the structure is expected to be prepared into a photoanode for use in fields such as solar cells.

Influence of the thickness of ZrO2 buffer layer on the electrical and optical properties of VO2 films

In this study, high-quality thermochromic vanadium dioxide (VO2) thin films were grown on ZrO2/glass by pulsed laser deposition and were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), double beam spectrophotometry and Hall Effect measurement system. Based on XRD results, it can be inferred that the crystal structure of ZrO2 buffer layer can be transformed between monoclinic and tetragonal structures with the increase of buffer layer thickness. Photoelectric performance tests showed that the introduction of ZrO2 buffer layer considerably reduced the phase transition temperature (Tc) and hysteresis loop width (ΔH) of the VO2 films and allowed the visible light transmittance (Tlum) and solar modulation ability (ΔTsol) of the films to be tuned effectively. Especially, when the thickness of the ZrO2 buffer layer was 50 nm, the Tc of the VO2 films reached the minimum value of 48 °C. When the ZrO2 buffer layer thickness increased to 125 nm, the sheet resistance change of the VO2 film attained two orders of magnitude, and their Tlum-90°C and ΔTsol were as high as 50.01% and 7.88%, respectively. These results showed that the ZrO2 buffer layer considerably affected the growth of VO2 films on amorphous glass substrates and was beneficial for the application of VO2 in energy-saving smart windows.

Insights into the Photoassisted Electrocatalytic Reduction of CO2 over a Two‐dimensional MoS2 Nanostructure Loaded on SnO2 Nanoparticles

AbstractPhotoelectrochemical reduction of CO2 to value‐added chemicals and fuels is an attractive strategy to store renewable energy and mitigate greenhouse gas emissions. In this study, based on the density functional theory (DFT) calculation, a two‐dimensional nanostructure MoS2 loaded on SnO2 nanoparticles (MS/SON) was prepared for photoassisted electrocatalytic reduction of CO2 to HCOOH through a two‐step process of facile hydrothermal and pyrolysis method. Through physical structure characterization and photoelectric performance test, the results indicated that the 5 % MS/SON exhibits exclusive HCOOH selectivity, the maximum FE is 43.8 %, the current density reached to 9 mA cm−2 at −1.4 V and the photocurrent value is 12.5 μA cm−2 under 0.5 V bias. The overpotential is as low as 245 mV. Besides, after the introduction of MoS2, there is a red shift in the adsorption band edge from 380 nm to 500 nm, indicating an enhancement of light response; the peak intensity of photoluminescence (PL) decreased, showing that the electron and hole are effectively separated; the values of electrochemical impedance spectroscopy (EIS) and Tafel plots (70 mV dec−1) were smaller than other ratios, demonstrating that the faster charge transfer rate; the proper introduction of MoS2 increased the specific surface area from 47.64 m2 g−1 to 55.99 m2 g−1, which was helpful to expand the number of active sites. It is demonstrated that MS/SON is an excellent CO2 reduction material.

Iridium size effects in localized surface plasmon-enhanced diamond UV photodetectors

Localized surface plasmon-enhanced diamond UV photodetectors with different Ir nanoisland arrays had been successfully fabricated. Three different Ir nanoisland arrays with the diameters of 20(D20), 30(D30) and 40(D40) nm were deposited on the diamond surface, respectively, and their height was 10 nm. Ti/Au metal electrodes were patterned on Ir nanoisland arrays area and bare diamond surface to form UV photodetectors. According to photoelectric performance test results, the responsivities of diamond photodetectors with Ir nanoislands were far greater than that of diamond photodetector, and the D40 showed the highest photocurrent and responsivity at 210 nm, and the D20 indicated the highest UV/vis rejection ratio. The results of simulated extinction spectra exhibited three resonance peaks at UV and visible region for each sample, indicating that D20 had the highest ratio of UV/vis, which was coincide with experiment results.

Economical and highly efficient Pt-free counter electrode for dye-sensitized solar cells

Fe-Co nanoparticle-incorporated carbon nanofibers ((Fe-Co)-CNFs) were obtained by a simple and flexible electrospinning method and were further pre-oxidized and carbonized under a high-temperature nitrogen atmosphere for application as counter electrodes for highly efficient platinum-free dye-sensitized solar cells (DSSCs). Electrochemical characterizations revealed that the (Fe-Co)-CNFs showed excellent electrocatalytic activity for the I3−/I− redox couple. Photoelectric performance tests have shown that dye-sensitized solar cells equipped with (Fe-Co)-CNF counter electrodes have comparable photovoltaic efficiency to platinum counter electrode cells. This is because the graphite properties of these fibers rendered them electronically conducting. One-dimensional nanofibers provide oriented electron transport pathways, while lapped fibers form a three-dimensional mesoporous network, enhancing the contact with the electrolyte, and hence leading to faster ionic reaction kinetics. This study demonstrates that (Fe-Co)-CNFs can be used as low-cost high-efficiency counter electrodes for DSSCs.

A g-C3N4@ppy-rGO 3D structure hydrogel for efficient photocatalysis

We propose a non-metallic g-C3N4 nanosheet with efficient photo-oxidation and reduction ability that is modified by two non-metallic materials graphene and polypyrrole. The composite was tested by water treatment, including hexavalent chromium and phenol. It offers a visible response, easy recovery, and high stability, with a higher photo-degradation rate than bulk g-C3N4. The photoelectric performance test showed that the composite has a reduced Eg (2.58 eV) that is 0.12 eV lower than g-C3N4 (2.70 eV). The rGH can transfer electrons, and ppy can transfer holes, which helps improve the separation rate of photogenerated charge of the g-C3N4. When ppy and rGH operate concurrently, the separation of the photogenerated charge is greatly improved. In addition, the results of Vb-XPS show that the value of the valence band top of the hybrid hydrogel is more negative than bulk g-C3N4. Therefore, the π-π conjugation of ppy and rGH can effectively improve the utilization rate of visible light, the photogenerated transfer rate, the photocatalysis-oxidation ability, and the change in valence band position of g-C3N4.