Towards High Performance: Solution-Processed Perovskite Solar Cells with Cu-Doped CH3NH3PbI3.

Perovskite solar cells (PSCs) have demonstrated remarkable photovoltaic performance, positioning themselves as promising devices in the field. Theoretical calculations suggest that copper (Cu) can serve as an effective dopant, potentially occupying interstitial sites in the perovskite structure, thereby reducing the energy barrier and enhancing carrier extraction. Subsequent experimental investigations confirm that adding CuI as an additive to MAPbI3-based perovskite cells improves optoelectronic properties and overall device performance. Optimizing the amount of Cu (0.01 M) has been found to significantly enhance crystalline quality and grain size, leading to improved light absorption and suppressed carrier recombination. Consequently, the power conversion efficiency (PCE) of Cu-doped PSCs increased from 16.3% to 18.2%. However, excessive Cu doping (0.1 M) negatively impacts morphology, resulting in inferior optical properties and diminished device performance. Furthermore, Cu-doped PSCs exhibit higher stabilized power output (SPO) compared to pristine cells. This study underscores the substantial benefits of Cu doping for advancing the development of highly efficient PSCs.

Bismuth-Based Metal-Organic Framework as a Chemiresistive Sensor for Acetone Gas Detection.

Analyzing acetone in the exhaled breath as a biomarker has proved to be a non-invasive method to detect diabetes in humans with good accuracy. In this work, a Bi-gallate MOF doped into a chitosan (CS) matrix containing an ionic liquid (IL) was fabricated to detect acetone gas with a low detection limit of 10 ppm at an operating temperature of 60 °C and 5 V operating bias. The sensor recorded the highest response to acetone in comparison to other test gases, proving its high selectivity along with long-term stability and repeatability. The sensor also exhibited ultra-fast response and recovery times of 15 ± 0.25 s and 3 ± 0.1 s, respectively. Moreover, the sensor membrane also exhibited flexibility and ease of fabrication, making it ideal to be employed as a real-time breath analyzer.

Ag Nanocluster Production through DC Magnetron Sputtering and Inert Gas Condensation: A Study of Structural, Kelvin Probe Force Microscopy, and Optical Properties.

Silver nanoclusters are valuable for a variety of applications. A combination of direct current (DC) magnetron sputtering and inert gas condensation methods, employed within an ultra-high vacuum (UHV) system, was used to generate Ag nanoclusters with an average size of 4 nm. Various analytical techniques, including Scanning Probe Microscopy (SPM), X-ray Diffraction (XRD), Kelvin Probe Force Microscopy (KPFM), UV-visible absorption, and Photoluminescence, were employed to characterize the produced Ag nanoclusters. AFM topographic imaging revealed spherical nanoparticles with sizes ranging from 3 to 6 nm, corroborating data from a quadrupole mass filter (QMF). The XRD analysis verified the simple cubic structure of the Ag nanoclusters. The surface potential was assessed using KPFM, from which the work function was calculated with a reference highly ordered pyrolytic graphite (HOPG). The UV-visible absorption spectra displayed peaks within the 350-750 nm wavelength range, with a strong absorption feature at 475 nm. Additionally, lower excitation wavelengths resulted in a sharp peak emission at 370 nm, which became weaker and broader when higher excitation wavelengths were used.

Photocatalytic degradation of aqueous methylene blue using ca-alginate supported ZnO nanoparticles: point of zero charge role in adsorption and photodegradation.

A novel insoluble Ca-Alginate created from soluble Na-Alginate was used as a support substrate for ZnO nanoparticles producing ZnO@Ca-Alginate composite photocatalyst. Fourier Transform Infrared (FT-IR), Ultraviolet-Visible (UV-Vis), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD) analysis techniques were used in the characterization of the prepared ZnO@Ca-Alginate. The ZnO@Ca-Alginate was tested for its potential use in the photodegradation of Methylene Blue (MB) from an aqueous solution under solar-simulated light. This composite photocatalyst efficiency in MB removal was compared with naked ZnO potential considering different conditions and parameters (e.g. pH, MB concentration, amount of photocatalyst, and irradiation time). The MB concentrations were identified using UV-vis spectrophotometric methods. While, high-performance liquid chromatography (HPLC), Total organic carbon (TOC) analysis, and other elemental analyses were used to confirm the MB complete mineralization. The MB photodegradation results were performed by using UV-vis analysis., the results showed that up to 95% of MB (40 mL, 40 ppm) was removed within 30 min of irradiation using either ZnO@Ca-Alginate or naked ZnO. The pH and the zero-charge point (Pzc) values play a main role in the adsorption and photodegradation results. The Pzc values for Ca-Alginate, ZnO, and Zn@Ca-Alginate were 6.5, 8.8, and 6.8 respectively. The prepared composite catalyst showed a maximum adsorption and photodegradation in a basic to slightly basic medium, the MB completely removed at pH of 7.7 within an hour of irradiation. The complete miniralzation of MB at the end of the photodegrdation process was confirmed. Here it is proved that the ZnO@Ca-Alginate photocatalyst can be recovered and reused without any significant decrease in its effectiveness.

Enhancing Hydrogen Sulfide Detection at Room Temperature Using ZIF-67-Chitosan Membrane.

Developing new materials for energy and environment-related applications is a critical research field. In this context, organic and metal-organic framework (MOF) materials are a promising solution for sensing hazardous gases and saving energy. Herein, a flexible membrane of the zeolitic imidazole framework (ZIF-67) mixed with a conductivity-controlled chitosan polymer was fabricated for detecting hydrogen sulfide (H2S) gas at room temperature (RT). The developed sensing device remarkably enhances the detection signal of 15 ppm of H2S gas at RT (23 °C). The response recorded is significantly higher than previously reported values. The optimization of the membrane doping percentage achieved exemplary results with respect to long-term stability, repeatability, and selectivity of the target gas among an array of several gases. The fabricated gas sensor has a fast response and a recovery time of 39 s and 142 s, respectively, for 15 ppm of H2S gas at RT. While the developed sensing device operates at RT and uses low bias voltage (0.5 V), the requirement for an additional heating element has been eliminated and the necessity for external energy is minimized. These novel features of the developed sensing device could be utilized for the real-time detection of harmful gases for a healthy and clean environment.

Real-time COVID-19 detection via graphite oxide-based field-effect transistor biosensors decorated with Pt/Pd nanoparticles.

Coronavirus 2019 (COVID-19) spreads an extremely infectious disease where there is no specific treatment. COVID-19 virus had a rapid and unexpected spread rate which resulted in critical difficulties for public health and unprecedented daily life disruption. Thus, accurate, rapid, and early diagnosis of COVID-19 virus is critical to maintain public health safety. A graphite oxide-based field-effect transistor (GO-FET) was fabricated and functionalized with COVID-19 antibody for the purpose of real-time detection of COVID-19 spike protein antigen. Thermal evaporation process was used to deposit the gold electrodes on the surface of the sensor substrate. Graphite oxide channel was placed between the gold electrodes. Bimetallic nanoparticles of platinum and palladium were generated via an ultra-high vacuum (UHV) compatible system by sputtering and inert-gas condensation technique. The biosensor graphite oxide channel was immobilized with specific antibodies against the COVID-19 spike protein to achieve selectivity and specificity. This technique uses the attractive semiconductor characteristics of the graphite oxide-based materials resulting in highly specific and sensitive detection of COVID-19 spike protein. The GO-FET biosensor was decorated with bimetallic nanoparticles of platinum and palladium to investigate the improvement in the sensor sensitivity. The in-house developed biosensor limit of detection (LOD) is 1 fg/mL of COVID-19 spike antigen in phosphate-buffered saline (PBS). Moreover, magnetic labelled SARS-CoV-2 spike antibody were studied to investigate any enhancement in the sensor performance. The results indicate the successful fabrication of a promising field effect transistor biosensor for COVID-19 diagnosis.

Metal-organic frameworks for advanced transducer based gas sensors: review and perspectives.

The development of gas sensing devices to detect environmentally toxic, hazardous, and volatile organic compounds (VOCs) has witnessed a surge of immense interest over the past few decades, motivated mainly by the significant progress in technological advancements in the gas sensing field. A great deal of research has been dedicated to developing robust, cost-effective, and miniaturized gas sensing platforms with high efficiency. Compared to conventional metal-oxide based gas sensing materials, metal-organic frameworks (MOFs) have garnered tremendous attention in a variety of fields, including the gas sensing field, due to their fascinating features such as high adsorption sites for gas molecules, high porosity, tunable morphologies, structural diversities, and ability of room temperature (RT) sensing. This review summarizes the current advancement in various pristine MOF materials and their composites for different electrical transducer-based gas sensing applications. The review begins with a discussion on the overview of gas sensors, the significance of MOFs, and their scope in the gas sensing field. Next, gas sensing applications are divided into four categories based on different advanced transducers: chemiresistive, capacitive, quartz crystal microbalance (QCM), and organic field-effect transistor (OFET) based gas sensors. Their fundamental concepts, gas sensing ability towards various gases, sensing mechanisms, and their advantages and disadvantages are discussed. Finally, this review is concluded with a summary, existing challenges, and future perspectives.

COVID-19 Detection via Silicon Nanowire Field-Effect Transistor: Setup and Modeling of Its Function.

Biomolecular detection methods have evolved from simple chemical processes to laboratory sensors capable of acquiring accurate measurements of various biological components. Recently, silicon nanowire field-effect transistors (SiNW-FETs) have been drawing enormous interest due to their potential in the biomolecular sensing field. SiNW-FETs exhibit capabilities such as providing real-time, label-free, highly selective, and sensitive detection. It is highly critical to diagnose infectious diseases accurately to reduce the illness and death spread rate. In this work, a novel SiNW-FET sensor is designed using a semiempirical approach, and the electronic transport properties are studied to detect the COVID-19 spike protein. Various electronic transport properties such as transmission spectrum, conductance, and electronic current are investigated by a semiempirical modeling that is combined with a nonequilibrium Green's function. Moreover, the developed sensor selectivity is tested by studying the electronic transport properties for other viruses including influenza, rotavirus, and HIV. The results indicate that SiNW-FET can be utilized for accurate COVID-19 identification with high sensitivity and selectivity.

Organic/Inorganic-Based Flexible Membrane for a Room-Temperature Electronic Gas Sensor.

A room temperature (RT) H2S gas sensor based on organic-inorganic nanocomposites has been developed by incorporating zinc oxide (ZnO) nanoparticles (NPs) into a conductivity-controlled organic polymer matrix. A homogeneous solution containing poly (vinyl alcohol) (PVA) and ionic liquid (IL) and further doped with ZnO NPs was used for the fabrication of a flexible membrane (approx. 200 µm in thickness). The sensor was assessed for its performance against hazardous gases at RT (23 °C). The obtained sensor exhibited good sensitivity, with a detection limit of 15 ppm, and a fast time response (24 ± 3 s) toward H2S gas. The sensor also showed excellent repeatability, long-term stability and selectivity toward H2S gas among other test gases. Furthermore, the sensor depicted a high flexibility, low cost, easy fabrication and low power consumption, thus holding great promise for flexible electronic gas sensors.

Flexible Cu3(HHTP)2 MOF Membranes for Gas Sensing Application at Room Temperature.

Mixed matrix membranes (MMMs), possessing high porosity, have received extensive attention for gas sensing applications. However, those with high flexibility and significant sensitivity are rare. In this work, we report on the fabrication of a novel membrane, using Cu3(HHTP)2 MOF (Cu-MOF) embedded in a polymer matrix. A solution comprising a homogenous suspension of poly-vinyl alcohol (PVA) and ionic liquid (IL), and Cu-MOF solid particles, was cast onto a petri dish to obtain a flexible membrane (215 µm in thickness). The sensor membrane (Cu-MOF/PVA/IL), characterized for its structure and morphology, was assessed for its performance in sensing against various test gases. A detection limit of 1 ppm at 23 °C (room temperature) for H2S was achieved, with a response time of 12 s. Moreover, (Cu-MOF/PVA/IL) sensor exhibited excellent repeatability, long-term stability, and selectivity towards H2S gas. The other characteristics of the (Cu-MOF/PVA/IL) sensor include high flexibility, low cost, low-power consumption, and easy fabrication technique, which nominate this sensor as a potential candidate for use in practical industrial applications.

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application.

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO3) nanoparticles. The sensing membranes fabricated were used to detect H2S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20 °C, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H2S gas in both indoor and outdoor atmospheres.

Sm3+-doped strontium barium borate phosphor for white light emission: Spectroscopic properties and Judd-Ofelt analysis.

This study aims to explore the spectroscopic properties of a Sr1.0Ba2.0B6O12:0.5Sm3+ phosphor synthesized using the solid-state reaction method. The morphology and elemental composition of the phosphor were determined using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. Phase changes and crystallite phases in the phosphor were studied using differential-scanning calorimetry and X-ray diffraction, respectively. Raman and Fourier-transform infrared spectra were used to identify the molecular vibrations in the phosphor. The energy bandgap and bonding nature of the phosphor were analyzed using the absorption spectrum. The nephelauxetic ratios determined from the absorption peaks revealed the presence of both ionic and covalent bonding in the phosphor. Judd-Ofelt parameters, along with radiative properties of the phosphor, were evaluated using the peaks in the absorption spectrum. Colorimetric analysis using the photoluminescence spectrum showed that the Sr1.0Ba2.0B6O12:0.5Sm3+ phosphor emits a cool-white light. The higher values of the spectroscopic quality factor, stimulated-emission cross-section, quantum efficiency, and the white-light emission of the phosphor suggest that Sr1.0Ba2.0B6O12:0.5Sm3+ is useful for display and lighting applications.