Improved Fluorescence and Photoelectrical Properties of CsPbBr3 by Constructing Heterojunctions under Pressure.

All-inorganic cesium lead bromide quantum dots (CsPbBr3 -QD) compounds are potential candidates for optoelectronic devices, because of their excellent fluorescence luminescence and thermal stability. However, the many heterojunction interfaces and large band gap induce the low power conversion efficiency in the CsPbBr3 -QD heterojunction, limiting its practical applications. Hereby, in combination with the pressure regulation and TiO2 /CsPbBr3 -QD heterojunction, the interface interaction within the heterojunction can be enhanced and the band gap can be narrowed. The pressure-induced O─Ti─O bond softening and PbBr6 octahedron stiffening at the interface region significantly enhance the interface interactions that are favorable to the carrier transport. Compared with CsPbBr3 -QD, the atomic interaction between Pb and Br of TiO2 /CsPbBr3 -QD heterojunction can be dramatically enhanced at high pressures, leading to increased band gap narrowing rate by two times, which is useful to widen the absorption spectrum. The fluorescence intensity increases by two times. Compression increases the photocurrent and maintains it after the pressure is released, which is due to the enhanced interface interaction induced by the high pressure. The findings provide new opportunities to adjust the physical properties of perovskite heterogeneous structures, and have important applications in the field of new-generation photovoltaic devices.

Highly Active Hydrogen-rich Photothermal Reverse Water Gas Shift Reaction on Ni/LaInO3 Perovskite Catalysts with Near-unity Selectivity.

Photo-assisted reverse water gas shift (RWGS) reaction is regarded green and promising in controlling the reaction gas ratio in Fischer Tropsch synthesis. But it is inclined to produce more byproducts in high H2 concentration condition. Herein, LaInO3 loaded with Ni-nanoparticles (Ni NPs) was designed to obtain an efficient photothermal RWGS reaction rate, where LaInO3 was enriched with oxygen vacancies to roundly adsorbing CO2 and the strong interaction with Ni NPs endowed the catalysts with powerful H2 activity. The optimized catalyst performed a large CO yield rate (1314 mmol gNi -1 h-1 ) and ≈100 % selectivity. In situ characterizations demonstrated a COOH* pathway of the reaction and photoinduced charge transfer process for reducing the RWGS reaction active energy. Our work provides valuable insights on the construction of catalysts concerning products selectivity and photoelectronic activating mechanism on CO2 hydrogenation.

Effect of (102) Diffracted Peak on Magnetic, Photoelectric, and Adhesive Characteristics of Fe2Si Films.

Fe2Si films with thicknesses from 100 nm to 600 nm underwent the following processes; (a) as-deposited films were maintained at room temperature (RT); (b) deposited films were post-annealed at 150 °C for 1 h, and (c) deposited films were post-annealed at a treatment temperature of 250 °C for 1 h. The X-ray diffraction (XRD) patterns of Fe2Si included significant (102) and (200) diffractions with corresponding peaks at 2∅are 44° and 53°, respectively. The (102) diffracted intensity and grain size of thicker and post-annealed Fe2Si thin films exceeded those of thinner and as-deposited Fe2Si thin films. The Fe2Si (102) peak revealed magneto-crystalline anisotropy, which reduced electrical resistivity and was associated with the highest low-frequency alternative-current magnetic susceptibility (Χ ac). The maximum value of Χ ac was reached at a thickness of 600 nm at the optimal frequency (f res) of 10 Hz, which generated maximized spin sensitivity. The resistivity (ρ) declined as the Fe2Si thickness and post-annealing temperature increased, because grain boundaries and the thin-film surface scattered the electrons. The 600 nm-thick Fe2Si thin film that was post-annealed at 250 °C had the lowest ρ of around 2.1×104 Ω · cm. The as-deposited Fe2Si thin film with a thickness of 100 nm had the highest transmittance of approximately 48%. The maximum transmittance decreased slightly as the thickness increased and upon post-annealing. The surface energy of the as-deposited Fe2Si films exceeded those of post-annealed films, revealing that the adhesion of as-deposited Fe2Si films was stronger than that of post-annealed films owing to the degree of crystallinity.

An Opto-electrophysiology Neural Probe with Photoelectric Artifact-Free for Advanced Single-Neuron Analysis.

Opto-electrophysiology neural probes targeting single-cell levels offer an important avenue for elucidating the intrinsic mechanisms of the nervous system using different physical quantities, representing a significant future direction for brain-computer interface (BCI) devices. However, the highly integrated structure poses significant challenges to fabrication processes and the presence of photoelectric artifacts complicates the extraction and analysis of target signals. Here, we propose a highly miniaturized and integrated opto-electrophysiology neural probe for electrical recording and optical stimulation at the single-cell/subcellular level. The design of a total internal reflection layer addresses the photoelectric artifacts that are more pronounced in single-cell devices compared to conventional implantable BCI devices. Finite element simulations and electrical signal tests demonstrate that the opto-electrophysiology neural probe eliminates the photoelectric artifacts in the time domain, which represents a significant breakthrough for optoelectrical integrated BCI devices. Our proposed opto-electrophysiology neural probe holds substantial potential for promoting the development of in vivo BCI devices and developing advanced therapeutic strategies for neurological disorders.

Innovative detection mechanism for deltamethrin based on a dual-emitting Fluoroprobe and its application in a smartphone-based photoelectric conversion device.

Pyrethroids are widely used insecticides worldwide, while their on-site and rapid detection still faces technological challenges. Herein, an innovative detection mechanism was designed for deltamethrin, a typical kind of type II pyrethroids, based on a dual-emitting fluoroprobe consisting of NH2-SiQDs and Eu3+. Deltamethrin can rapidly hydrolyze into 3-phenoxybenzaldehyde (3-PBD) and react specifically with fluoroprobe, causing fluorescence quenching of SiQDs while maintaining the fluorescent stability of Eu3+. Building upon the above fluorescence-responsive principle, SiQDs@Eu3+ provided satisfactorily dual-emitting signals, realizing the highly-selective and sensitive detection of deltamethrin. Correlation between the surface structure of SiQDs and their absorption spectra was in-depth unraveled by TD-DFT calculation and FT-IR analysis. As for the analytical performance, the recovery and LOD of deltamethrin in lettuce, provided by SiQDs@Eu3+, were comparable or even superior over conventional chromatographic analysis. Meanwhile, an innovative smartphone-based optical device was developed, which greatly decreased errors caused by the previously reported smartphone-based fluorescence detection.

Regulation of the Buried Interface to Achieve Efficient HTL-Free All-Inorganic CsPbI2Br-Based Perovskite Solar Cells.

The large voltage loss (Vloss) mainly stems from the mismatch between the perovskite film and electron transport layer in CsPbI2Br-based all-inorganic perovskite solar cells (I-PSCs), which restricts the power conversion efficiency (PCE) of devices. To address this issue, potassium benzoate (BAP) is first introduced as a bifunctional passivation material to regulate the TiO2/CsPbI2Br interface, reduce the Vloss, and improve the photovoltaic performance of CsPbI2Br-based I-PSCs. Eventually, the champion PCE of CsPbI2Br-based I-PSCs without a hole transport layer modified by BAP (Target-PSCs) improves to 14.90% from the 12.14% of reference PSCs. The open-circuit voltage (Voc) increases to 1.27 V from the initial 1.14 V after BAP modification. A series of characterizations show that BAP modification can not only optimize the energy level alignment of I-PSCs but also passivize the surface defects caused by uncoordinated Cs+/Pb2+. Moreover, the Target-PSCs without encapsulation demonstrate better thermal stability, which can maintain 107.6% of the original PCE after annealing at 160 °C for 140 min in humid air. While the reference PSCs only maintain 76.5% of their initial PCE after annealing at the same process. This work provides a simple strategy to modify the buried interface and improve the performance of CsPbI2Br-based I-PSCs.

Ultraviolet irradiation-controlled memory effect in graphene field-effect transistors.

Control of graphene memory devices using photons, via control of the charge-transfer process, is demonstrated by employing gate-voltage pulses to program/erase the memory elements. The hysteresis in the conductance-gate voltage-dependence of graphene field-effect transistors on a SiO2 substrate can be greatly enlarged by ultraviolet irradiation in both air and vacuum. An enhanced charge transfer between graphene and its surroundings, induced by ultraviolet illumination, is proposed.

Significantly Improved Efficiency and Stability of Pure Tin-Based Perovskite Solar Cells with Bifunctional Molecules.

Tin-based perovskite solar cells (TPSCs) have become one of the most prospective photovoltaic materials due to their remarkable optoelectronic properties and relatively low toxicity. Nevertheless, the rapid crystallization of perovskites and the easy oxidization of Sn2+ to Sn4+ make it challenging to fabricate efficient TPSCs. In this work, a piperazine iodide (PI) material with -NH- and -NH2+- bifunctional groups is synthesized and introduced into the PEA0.1FA0.9SnI3-based precursor solution to tune the microstructure, charge transport, and stability of TPSCs. Compared with piperazine (PZ) containing only the -NH- group, the PI additive displays better effects on regulating the microstructure and crystallization, inhibiting Sn2+ oxidation and reducing trap states, resulting in an optimal efficiency of 10.33%. This is substantially better than that of the reference device (6.42%). Benefiting from the fact that PI containing -NH- and -NH2+- groups can passivate both positively charged defects and negatively charged halogen defects, unencapsulated TPSCs modified with the PI material can maintain about 90% of their original efficiency after being kept in a N2 atmosphere for 1000 h, much higher than the value of 47% in reference TPSCs without additives. This work provides a practical method to prepare efficient and stable pure TPSCs.

Construction of a novel Cu1.8S/NH2-La MOFs decorated Black-TNTs photoanode electrode for high-efficiently photoelectrocatalytic degradation of 2, 4-dichlorophenol.

Photoelectrocatalysis (PEC) has long been regarded as an efficient and green method to eliminate various organic pollutants from wastewater. However, the lack of highly photoelectrocatalytic active and stable electrodes limits the development of the PEC technologies. Herein, a novel hierarchical photo-electrode with hollow Cu1.8S/NH2-La MOFs decorated black titanium dioxide nanotubes (Cu1.8S/NH2-La MOFs/Black TNTs) was fabricated by a two-step water-heating method. The prepared photoelectrode was used to degradation of 2, 4-dichlorophenol (2, 4-DCP). Analysis of photoelectrocatalytic degradation process of 2, 4-DCP was evaluated using UV-Vis absorption spectroscopy and the main degradation paths were analyzed by LC-MS. The results showed that 99.3% of the pollutant could be rapidly degraded within 180 min. Furthermore, the Cu1.8S/NH2-La MOFs/Black TNTs photoelectric pole exhibited excellent stability after 15 cycling experiments.

Application of sensor structures based on a photoelectric transducer to determine the activity of aspartate and alanine aminotransferases in blood plasma.

The successful application of a recombination sensor for the real-time detection of transaminasethe detection of transaminase activities (ALT/AST) in the blood plasma of rats has been demonstrated. The parameter directly measured in real time is the photocurrent through the structure with buried silicon barrier when light with high absorption coefficient is used. Detection is realized as a result of specific chemical reactions catalyzed byALTandASTenzymes (α-ketoglutarate + aspartate andα-ketoglutarate + alanine). The change of the effective charge of the reagents allows recording the activity of enzymes from photocurrent measurements. The main factor in this approach is the influence on the parameters of the recombination centers at the interface. The physical mechanism of the sensor structure can be explained within the framework of the Stevenson theory, taking into account the changes in the pre surface band bending, the capture cross sections and the energy position of the recombination levels during adsorption. The paper also offers theoretical analyze allowing optimization of analytical signals of recombination sensor. A promising approach to develop a simple and sensitive method for real time detection of transaminases activity has been discussed in detail.

Study on the photoelectrical performance of anodized titanium sheets.

Anodization is a widely used method to obtain multicoloured oxidized titanium sheets. However, most researchers paid great attention to the colour-related properties instead of photoelectrical properties of titanium oxide film obtained by anodization. In this work, to study their photoelectrical properties, a series of multicoloured oxidized titanium sheets were prepared by anodization method, and UV-vis absorption and photocurrents were tested. The relationship between anodization voltages/anodization durations and photocurrents of titanium sheets was studied. Results show that titanium sheets have excellent photoelectrical performance. With the increase of anodization voltage, the number of UV-vis absorption peaks increased under visible light which means increasing absorption. When anodization duration increased, absorption band edge also increased in the visible light region, which means the band gap needed to produce charge transfer transition decreased. Under simulated sunlight and applied voltage of +0.4 V, photocurrent increased with the increase of either anodization voltage or anodization duration, and can be expressed by linear equations. In addition, anodization currents were recorded during anodization. Morphology, crystal structure and photoelectrical properties of anodized titanium sheets were characterized. The anodized titanium sheets can not only be used as decorative material in jewellery and architecture fields etc. but also are supposed to be used as photoelectrical catalyst in further work.

Photoelectrical Dynamics Uplift in Perovskite Solar Cells by Atoms Thick 2D TiS2 Layer Passivation of TiO2 Nanograss Electron Transport Layer.

A deficiency in the photoelectrical dynamics at the interface due to the surface traps of the TiO2 electron transport layer (ETL) has been the critical factor for the inferiority of the power conversion efficiency (PCE) in the perovskite solar cells. Despite its excellent energy level alignment with most perovskite materials, its large density of surface defect as a result of sub lattice vacancies has been the critical hurdle for an efficient photovoltaic process in the device. Here, we report that atoms thick 2D TiS2 layer grown on the surface of a (001) faceted and single-crystalline TiO2 nanograss (NG) ETL have effectively passivated the defects, boosting the charge extractability, carrier mobility, external quantum efficiency, and the device stability. These properties allow the perovskite solar cells (PSCs) to produce a PCE as high as 18.73% with short-circuit current density (Jsc), open-circuit voltage (Voc), and fill-factor (FF) values as high as 22.04 mA/cm2, 1.13 V, and 0.752, respectively, a 3.3% improvement from the pristine TiO2-NG-based PSCs. The present approach should find an extensive application for controlling the photoelectrical dynamic deficiency in perovskite solar cells.

High-Capacity, Fast-Response, and Photocapacitor-Based Terpolymer Phosphor Composite.

This paper describes a new class of light transducer-based poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) terpolymer doped with 50% wt. phosphor particles that enables to efficiently transform light energy into an electrical signal. Broadband dielectric characterization together with experimental results on photo-electric conversion demonstrated high capacitance variation of the proposed composite under light exposure, confirming promising potential of our sensor device for application in retinal prostheses where the converted electrical signal can affect the biological activity of the neuron system. In addition to the benefit of being light-weight, having ultra-flexibility, and used in a simple process, the proposed photodetector composite leads to fast response and high sensibility in terms of photoelectrical coupling where significant increases in capacitance change of 78% and 25% have been recorded under blue and green light sources, respectively. These results demonstrated high-performance material design where phosphor filler contributes to promote charge-discharge efficiency as well as reduced dielectric loss in P(VDF-TrFE-CTFE), which facilitate the composite for flexible light transducer applications, especially in the medical environment.

Photophysical Properties of Multilayer Graphene-Quantum Dots Hybrid Structures.

Photoelectrical and photoluminescent properties of multilayer graphene (MLG)-quantum dots (QD) hybrid structures have been studied. It has been shown that the average rate of transfer from QDs to the MLG can be estimated via photoinduced processes on the QDs' surfaces. A monolayer of CdSe QDs can double the photoresponse amplitude of multilayer graphene, without influencing its characteristic photoresponse time. It has been found that efficient charge or energy transfer from QDs to MLG with a rate higher than 3 × 108 s-1 strongly inhibits photoinduced processes on the QD surfaces and provides photostability for QD-based structures.

Tailoring Bandgap of Perovskite BaTiO3 by Transition Metals Co-Doping for Visible-Light Photoelectrical Applications: A First-Principles Study.

The physical and chemical properties of V-M″ and Nb-M″ (M″ is 3d or 4d transition metal) co-doped BaTiO3 were studied by first-principles calculation based on density functional theory. Our calculation results show that V-M″ co-doping is more favorable than Nb-M″ co-doping in terms of narrowing the bandgap and increasing the visible-light absorption. In pure BaTiO3, the bandgap depends on the energy levels of the Ti 3d and O 2p states. The appropriate co-doping can effectively manipulate the bandgap by introducing new energy levels interacting with those of the pure BaTiO3. The optimal co-doping effect comes from the V-Cr co-doping system, which not only has smaller impurity formation energy, but also significantly reduces the bandgap. Detailed analysis of the density of states, band structure, and charge-density distribution in the doping systems demonstrates the synergistic effect induced by the V and Cr co-doping. The results can provide not only useful insights into the understanding of the bandgap engineering by element doping, but also beneficial guidance to the experimental study of BaTiO3 for visible-light photoelectrical applications.

Development of in situ optical-electrical MEMS platform for semiconductor characterization.

In situ transmission electron microscopy (TEM) technology has become one of the fastest growing areas in TEM research in recent years. This technique allows researchers to investigate the dynamic response of materials to external stimuli inside the microscope. Optoelectronic functional semiconducting materials play an irreplaceable role in several key fields such as clean energy, communications, and pollution disposal. The ability to observe the dynamic behavior of these materials under real working conditions using advanced TEM technologies would provide an in-depth understanding of their working mechanisms, enabling further improvement of their properties. In this work, we designed a microelectromechanical-system-chip-based system to illuminate a sample inside a transmission electron microscope. This system allows simultaneous in situ optical and electrical measurements, which are crucial for optoelectronic semiconductor characterization.