Silver Bismuth Research Articles

Surface p-type band bending and energy level alignment minimizes voltage loss in perovskite solar cells

Due to the significant energy level mismatch and contact energy loss between the perovskite absorber layer and p-type hole-transporting layer (HTL), there exists a large hole transport barrier between the perovskite absorber layer and HTL, which hinders hole transport and leads to lower open circuit voltage (VOC) in perovskite devices. Therefore, the surface contact process between the perovskite film and the hole-transporting layer becomes particularly important. Here, we doped cesium silver bismuth bromide (Cs2AgBiBr6) quantum dots (QDs) into ethyl acetate (EA) as an anti-solvent to achieve the formation of a bulk heterojunction structure with quantum dot solution on the surface of the MAPbI3 perovskite film. The perovskite film exhibits appropriate band edge bending and forms a p-type semiconductor. This facilitates the directed transport of photo-induced charge carriers to the hole-transporting layer, reducing carrier recombination losses and enhancing the collection efficiency of holes by the HTL. Through characterization experiments, we have found that this method significantly improves the VOC and photovoltaic conversion efficiency (PCE) of perovskite solar cells. The perovskite solar cells fabricated using this method show a better PCE with a VOC of 1.06 V.

Enhanced light driven CO2 conversion based on silver bismuth sulfide hollow octahedrons coated with amorphous metal–organic frameworks

AgBiS2 hollow octahedrons coated with ZIF-67 outer layers formed a core–shell heterostructure with more favorable charge transfer kinetics, which conduced to electron accumulation and photosensitizer adsorption for CO2 photoreduction.

High entropy effect on thermoelectric properties of the nonequilibrium cubic phase of AgBiSe2-2xSxTex with x = 0-0.6.

Silver bismuth diselenide (AgBiSe2) has attracted much attention as an efficient thermoelectric material owing to its low thermal conductivity. However, AgBiSe2 exhibits multiple crystal structural transitions with temperature, and high thermoelectric performance was realized only in the high-temperature cubic phase. We previously reported the stabilization of the cubic phase in AgBiSe2-2xSxTex with x = 0.6-0.8 at room temperature using a high-entropy-alloy (HEA) approach. In this paper, we succeeded in stabilizing the cubic phase in AgBiSe2-2xSxTex with x = 0-0.6 using an ice-quenching method and investigated the HE effect on thermoelectric properties below room temperature to avoid the emergence of a hexagonal phase above room temperature. Cubic AgBiSe2-2xSxTex exhibited n-type conductivity at 10-300 K. The increase in electrical conductivity is due to a combined effect of increased charge density and electron mobility, depending on the sample. It is evident that charge carrier density strongly increases in the x = 0.4 sample while the mobility remains roughly the same compared to the x = 0.0 sample. In x = 0.2 and 0.6 samples, electronic conductivity increases primarily due to enhanced mobility. S and Te substitutions induced a variation in the band structure, resulting in carrier mobility enhancement. Furthermore, thermal conductivity showed reduction tendency with increasing amounts of S and Te due to the enhancement of phonon scattering. Simultaneous electronic conductivity increase and thermal conductivity reduction resulted in the systematic improvement of ZT values for HE-type cubic AgBiSe2-2xSxTex.

Cation exchange synthesis of AgBiS2 quantum dots for highly efficient solar cells.

Silver bismuth sulfide (AgBiS2) nanocrystals have emerged as a promising eco-friendly, low-cost solar cell absorber material. Their direct synthesis often relies on the hot-injection method, requiring the application of high temperatures and vacuum for prolonged times. Here, we demonstrate an alternative synthetic approach via a cation exchange reaction. In the first-step, bis(stearoyl)sulfide is used as an air-stable sulfur precursor for the synthesis of small, monodisperse Ag2S nanocrystals at room-temperature. In a second step, bismuth cations are incorporated into the nanocrystal lattice to form ternary AgBiS2 nanocrystals, without altering their size and shape. When implemented into photovoltaic devices, AgBiS2 nanocrystals obtained by cation exchange reach power conversion efficiencies of up to 7.35%, demonstrating the efficacy of the new synthetic approach for the formation of high-quality, ternary semiconducting nanocrystals.

Molecular Design of Layered Hybrid Silver Bismuth Bromine Single Crystal for Ultra-Stable X-Ray Detection With Record Sensitivity.

Nowadays, weak interlayer coupling and unclear mechanism in layered hybrid silver bismuth bromine (LH-AgBiBr) are the main reasons for limiting its further enhanced X-ray detection sensitivity and stability. Herein, the design rules for LH-AgBiBr and its influence on X-ray detection performance are reported for the first time. Although shortening amine size can enhance interlayer coupling, its detection performance is severely hampered by its easier defect formation caused by enlarged micro strain. In contrast, an appropriate divalent amine design endows the material with improved interlayer coupling and released micro strain, which benefits crystal stability and mechanical hardness. Another contribution is to increase material density and dielectric constant; thus, enhancing X-ray absorption and carrier transport. Consequently, the optimized parallel device based on BDA2 AgBiBr8 achieves a record sensitivity of 2638 µC Gyair -1 cm-2 and an ultra-low detection limit of 7.4 nGyair s-1 , outperforming other reported LH-AgBiBr X-ray detectors. Moreover, the unencapsulated device displays remarkable anti-moisture, anti-thermal (>150 °C), and anti-radiation (>1000 Gyair ) endurance. Eventually, high-resolution hard X-ray imaging is demonstrated by linear detector arrays under a benign dose rate (1.63 µGyair s-1 ) and low external bias (5V). Hence, these findings provide guidelines for future materials design and device optimization.

Fabrication of ambient processed carbon-based inorganic silver bismuth iodide solar cells without any expensive hole transport materials

Recently, tremendous progress has been made in inorganic–organic hybrid lead halide perovskite solar cells (PSCs). Still, most of the reported high-efficiency PSCs were made with harmful lead (Pb), which is one of the major obstacles to large-scale adoption. Silver bismuth iodide (AgBiI4) light absorbers have been identified as promising lead-free and low-toxic metal-halide materials for solar cell applications. Here, we present hole transport material (HTM) and lead-free carbon-based inorganic Rudorffite (AgBiI4) solar cells, which can be prepared by simple spin-coating using silver iodide and bismuth iodide precursors under ambient conditions. Powder X-ray diffraction (XRD), UV–visible absorption, and field emission scanning electron microscopy (FESEM) studies were used to characterize the deposited films. The performance of the fabricated device was studied using incident photon-to-current conversion efficiency (IPCE) and current density–voltage (J-V) characteristics. Electrochemical impedance spectroscopy (EIS) was used to investigate the charge transfer process at the interface of the fabricated device. Under standard illumination test conditions, the fabricated device showed a photoelectric conversion efficiency (PCE) of 1.04%. The devices also have good stability and retained 96% of their initial PCE after 200 hrs of storage in ambient conditions. This work demonstrates the potential of HTM-free, ambient processable, and lead-free Rudorffite stable solar cells.

Alloying Effects on Charge-Carrier Transport in Silver-Bismuth Double Perovskites.

Alloying is widely adopted for tuning the properties of emergent semiconductors for optoelectronic and photovoltaic applications. So far, alloying strategies have primarily focused on engineering bandgaps rather than optimizing charge-carrier transport. Here, we demonstrate that alloying may severely limit charge-carrier transport in the presence of localized charge carriers (e.g., small polarons). By combining reflection-transmission and optical pump-terahertz probe spectroscopy with first-principles calculations, we investigate the interplay between alloying and charge-carrier localization in Cs2AgSbxBi1-xBr6 double perovskite thin films. We show that the charge-carrier transport regime strongly determines the impact of alloying on the transport properties. While initially delocalized charge carriers probe electronic bands formed upon alloying, subsequently self-localized charge carriers probe the energetic landscape more locally, thus turning an alloy's low-energy sites (e.g., Sb sites) into traps, which dramatically deteriorates transport properties. These findings highlight the inherent limitations of alloying strategies and provide design tools for newly emerging and highly efficient semiconductors.

Fabrication and characterization of (PVDF/PEO)/AgBiSe2 polymeric membrane with enhanced visible light photocatalytic performance

AbstractDriven by the visible band gap, silver bismuth selenide (AgBiSe2) was loaded in PVDF/PEO blend to enhance the photodegradation of Maxilon blue dye. AgBiSe2 nanoparticles were successfully synthesized by facile solvothermal approach and then loaded to PVDF/PEO (80/20) by 10, 20, and 30 wt%, by evaporative casting method. The X‐ray results in tandem with the Fourier transform infrared (FTIR) established the successful fabrication of (PVDF/PEO)/x(AgBiSe2) polymer nanocomposites. The X‐ray analysis verified the formation of hexagonal AgBiSe2 of a crystallite size ranging from 14.3 to 23.24 nm. The FT‐IR results manifested an overlap between functional groups that corroborated the interaction between PVDF and PEO. Peaks of the AgSe, and SeO modes confirmed that the nanofiller and PVDF/PEO blend were successfully incorporated. The micrograph images by field emission scanning electron microscope (FESEM) unraveled the high tendency of AgBiSe2 to form a uniform cluster. The optical band gap was found to be a direct band gap of 2.86 eV for 30 wt% AgBiSe2 proving its validity as visible‐light‐driven photocatalysts. The removal percentages of the prepared membrane are 4.1, 59, 82, and 98 for 0, 10%, 20%, and 30% AgBiSe2 after 300 min of irradiation under simulated sunlight at pH 6.

Dual facet passivation of silver halometallate for eco-friendly silver bismuth sulfide near IR photodetector

Ternary chalcogenide silver bismuth sulfide nanocrystals (AgBiS2 NCs) have taken great strides in the past few years to emerge as one of the better eco-friendly alternatives to compete with the prevalent toxic semiconductor materials such as lead sulfide quantum dots (PbS QDs) in the near-infrared (NIR) region. Nevertheless, their implementation in photodetectors has been scarce due to high dark current and complicated solid-state ligand exchange fabrication steps involved, resulting in a lower overall detectivity. The performance is further deemed to be stunted due to the difficulty associated with the passivation of the charge-neutral (100) facet of larger AgBiS2 NCs efficiently. In this work, we aimed to develop a mixed ‘halometallate’ ligand approach, wherein we introduce silver bromide (AgBr) as an ancillary ligand to silver iodide (AgI), passivating both (100) and (111) facets of cubic AgBiS2 solids in a facile solution-phase ligand exchange step to obtain highly dispersible colloidal ink. Decreased bond length, bond angle (Br-Ag-Br), and ionic size of [AgBr2-] anion induces less compressive strain compared to [AgI2–], culminating in higher molecular stability on the AgBiS2 surface. This dual passivation reduces the dark current to 6.01 × 10-7 A cm−2 and a high specific detectivity of 1.8 × 1012 Jones at 800 nm is achieved, comparable to ubiquitous PbS QD devices. We also demonstrate diminished in-gap carrier density population, enhanced light detection, and ultrafast microsecond response at higher wavelengths operating under high bias (-1V) photoconductive mode. This study illustrates the role of optimum surface coverage in eliminating the deleterious non-radiative recombination defect centers by introducing additional ligands in solution-processed AgBiS2 NC and the viability of the mixed ligand approach for stable eco-friendly NIR photodetectors.

Synergistic effect of AgBiS2 segregated NaV3O8 nanostructures in direct conversion X-ray sensors

Synergistic nanostructures possess enriched electrical and optical properties compared to conventional nanostructures. 1D-3D synergized nanostructure was implied to elucidate the performance of the X-ray sensor for the first time. Current research in X-ray detection only focuses on implementing high attenuating material based on oxides/ perovskites in developing X-ray sensors. Herein we approached tailoring the performance of an X-ray sensor with a synergistic nanostructure composed of sodium vanadium oxide (NaV3O8) with substantial grain boundary (GB) segregation of silver bismuth sulfide (AgBiS2), enabling the structured arrangement of nanostructured grains at the surface of NaV3O8 nanorods. Then, it was coated as a thick film on top of the interdigitated electrodes by glass rod sliding technique to readout the dose-dependent X-ray sensing capability. From the X-ray impinged photocurrent characteristics, the sensor with 75 wt% AgBiS2 segregated NaV3O8 exhibits superior sensitivity 82.6 nC mGy-1 cm-2 and low-noise equivalent dose rate 1.04 mGy Hz-0.5 for 2.49 mGy s-1 than other compositions. These experimental findings explore the implication of synergistic nanostructures as active layers in direct conversion X-rays sensors for improved charge extraction and enhancement in X-ray impinged photocurrent at low dose rates.

Enhanced surface morphology and photovoltaic properties of a new class of material copper silver bismuth iodide solar cell

Newly discovered copper silver bismuth iodide films have attracted a lot of interest as a lead-free emerging material for active layers of solar cells because of their promising optical and photovoltaic properties. This study is the first to describe the optimization of the annealing temperature of Cu6AgBiI10 solar cells. By using a single-step spin coating technique, the films were fabricated, in which hot casting drops were cast onto the preheated substrates. The trigonal crystal's structure was confirmed using X-Ray Diffraction and surface morphology was observed through scanning electron microscopes of synthesized films. The mapping of energy dispersive X-ray spectrometers confirms that the elements in the films are evenly distributed. In this work, we examine the optical and photovoltaic characteristics of the ITO/SnO2/Cu6AgBiI10/P3HT/C/Ag structure for the first time. Our optical investigation revealed high absorbance and low reflectivity CABI film at 150 °C. According to analysis of photovoltaic attributes, we were able to achieve maximum current density of 0.45 mA/cm2 and power conversion efficiency of 0.041%. These results should be helpful in the development of environmentally-friendly Cu–Ag–Bi–I base solar cells, as well as a variety of other devices such photo detectors or LED's.

Structure and photoluminescence properties of PbO–Bi2O3–Ga2O3 glass-ceramics containing silver nanoparticles, free lead and bismuth ions

We report the synthesis, structural characterization, and optical properties of PbO–Bi2O3–Ga2O3 glass-ceramics (GCs) containing PbO and Bi2O3 crystallites, free lead (Pb2+) and bismuth (Bi3+) ions, and silver nanoparticles (Ag-NPs). The samples were prepared by applying the melt-quenching method followed by suitable heat-treatment of the samples. Transmission Electron Microscopy, X-ray diffraction, linear optical absorption, and photoluminescence (PL) were the techniques applied to characterize the samples. When the samples were excited at 330 nm a large PL intensity, due to the Pb2+ and Bi3+, is observed. Moreover, large PL intensity enhancement of about 1000% for the samples containing Ag-NPs is observed in comparison with the PL intensity from the samples without Ag-NPs. This is the first time that this behavior is reported for a GCs based on heavy-metal oxides. The potential of this class of materials for photonic applications is discussed.

Studies on Synthesis and Characterization of a Chemically Deposited Nanostructured Thin Film of Ternary Compound Silver Bismuth Sulfide (AgBi2S3) onto n-Type Wide Band Gap Semiconducting Titanium Dioxide (TiO2)

Studies on Synthesis and Characterization of a Chemically Deposited Nanostructured Thin Film of Ternary Compound Silver Bismuth Sulfide (AgBi2S3) onto n-Type Wide Band Gap Semiconducting Titanium Dioxide (TiO2)

A Semitransparent Silver–Bismuth Iodide Solar Cell with Voc above 0.8 V for Indoor Photovoltaics

Because the toxicity of lead (Pb) remains a potential threat to the commercialization of perovskite solar cells, silver–bismuth halides such as AgBiI4, AgBi2I7, Ag2BiI5, and Ag3BiI6 with band gaps of 1.8–1.9 eV and strong absorption are considered to be promising alternatives to Pb-based perovskites, not only for outdoor (1 Sun) but also for indoor photovoltaics because their band gap matches best with the indoor artificial light spectrum. To date, almost all studies have focused on improving the power conversion efficiency (PCE) under 1 Sun using thick absorber films made on mesoporous electron-transport layers. However, in this work, we aimed at developing optically semitransparent Ag2BiI5 solar cells that can be used indoor or on windows. We studied the effect of the precursor composition on the phase evolution, energy band levels, film morphology, and, eventually, solar cell performance. Through compositional engineering and thickness optimization, we accomplished the fabrication of a thin (∼100 nm Ag2BiI5) and semitransparent Ag2BiI5 solar cell that works with a power conversion efficiency of ∼2%, which is greater than many reported with thick and opaque films and slightly lower than the best recorded for Ag2BiI5. The cell shows an open-circuit voltage (Voc) of over 800 mV, the highest reported for Ag2BI5. More interestingly, while a thicker/opaque cell was found to work with a PCE of 5.0% under 1000 lx, the semitransparent cell shows a reasonable performance of 3.3% under the same light intensity.

Enhanced Open-Circuit Voltage of Eco-Friendly Silver Bismuth Iodide Thin-Film Photovoltaics with PTB7 Polymer-Based Hole Transport Layer

Enhanced Open-Circuit Voltage of Eco-Friendly Silver Bismuth Iodide Thin-Film Photovoltaics with PTB7 Polymer-Based Hole Transport Layer

Grain size effect on direct conversion low-dose X-ray sensing nature of nanocrystalline silver bismuth sulfide

Nanocrystalline materials have garnered significant recognition in the scientific and research community for developing X-ray sensors. The applicability of bismuth-based binary and ternary compounds has been extensively studied in X-ray imaging and cancer therapy applications owing to their high attenuation. Among the binary and ternary compounds of bismuth, the n-type semiconductor silver bismuth sulfide (AgBiS2) was studied for the detection of X-rays at lower doses, based on its total attenuation (μ = 3.07 cm2 g−1 at 70 keV), density (ρ = 7.02 g cm−3), and bandgap (Eg = 1.21 eV). The effect of grain size on X-ray sensing performance was examined to validate the effective size required for maximum attenuation of X-rays and successful extraction of induced mobility carriers. X-ray sensors with four different AgBiS2 grain sizes were cast on interdigitated electrodes (IDEs) and subjected to different doses of X-rays at 2 V bias to study its dose-dependent X-ray sensing nature using an intra-oral (70 kVp-AC) X-ray machine. AgBiS2-based X-ray sensor exhibited the highest sensitivity of 20.13 μC mGy−1 cm−3 with the lowest Noise-equivalent dose ratio (NED) of 0.08 μGy Hz−0.5, 0.20 mGy detection limit and a response time of 0.12 s. This outcome validates that AgBiS2 can be applied as a potential replacement for perovskites in direct X-ray detection.

Modulating incident light for improved CO2 photoreduction in freestanding silver bismuth iodide/nanocellulose films with exotic gold nanoparticles

In response to the severe climate change caused by significant carbon dioxide emissions, researchers have been exploring the conversion of CO2 into carbon-based fuels through photocatalytic reactions inspired by photosynthesis. Particulate photocatalysts are known for their easy fabrication and diverse material configuration, with immobilization onto composite polymers enhancing reusability and practicality. In this study, we fabricated a novel freestanding photocatalyst composite film by immobilizing Ag3BiI6 (SBI) onto a nanocellulose (CNF) transparent film using a sequential process involving noble metal nanoparticle solutions and thermal evaporation of BiI3. The effect of the sequence and composition of Au and SBI/CNF on the morphology, optical property, and CO2 photoreduction performance was also investigated. The resulting SBI-Au/CNF film exhibited the highest photocatalytic activity for CO2 reduction, achieving a CO yield of 31.96 μmol/g⋅h with high stability for long-term photocatalytic reactions lasting 72 h. This study demonstrates the potential of photocatalytic materials to mitigate climate change by converting CO2 emissions into useful fuels.

Synthesis of cesium silver bismuth bromide double perovskite nanoparticles via a microwave-assisted solvothermal method

Bismuth-based perovskites have been widely investigated in recent years as an alternative candidate for resolving the toxicity of a high-performance lead-based perovskite. In this work, we present the synthesis of a cesium silver bismuth bromide (Cs2AgBiBr6) perovskite employing a microwave-assisted solvothermal method, which offers features for simple and minute-scale sample synthesis. The X-ray diffraction and Raman spectroscopy results reflected the high purity of bismuth-based perovskites synthesized at non-inert conditions. Field-emission scanning electron microscopy and energy-dispersive X-ray showed a particle size of 72 nm and Br-rich or Cs-deficient condition in the materials, respectively. The synthesized material also shows promising moisture and thermal stability. Ultraviolet–visible spectroscopy and temperature-dependent photoluminescence spectroscopy revealed the electronic structure and nature of the material, including low carrier localization and a strong electron-phonon effect. The time-resolved photoluminescence revealed a carrier lifetime of 921 ns, which is desired for an optoelectronic application. These findings point to a simple and rapid method for producing Cs2AgBiBr6 perovskite nanoparticles.

Green Capture of Silver by Bismuth from Decoppered Anode Slime with Low Energy Consumption

As a consequence of lead pollution, low efficiency, and high energy consumption in the current pyrometallurgical processing of copper anode slime, a novel metallurgical recycling technology for processing copper anode slime was developed in this research. The new process uses bismuth instead of lead to realize high-efficiency enrichment of silver with lower energy consumption and higher capture efficiency. In this study, to determine the mechanism of silver capture by bismuth and confirm the possibility of low-temperature silver capture, the effects of coke powder, Na2CO3, SiO2, Bi2O3, and temperature on the silver content in slag during bismuth capture of precious metals were investigated. The results show that the silver content remaining in slag is only 0.157% with a Bi2O3 addition of 25% and a Na2O/SiO2 ratio of 0.417 at 950 °C for 8 h. The silver content in slag obtained from the proposed process was significantly lower than the allowable residue standard of China (silver content in slag <1%). The obtained bismuth–silver alloy can facilitate the recycling of bismuth through the blowing process. Considering that bismuth is a green metal, the pollution of lead in the silver recovery process is avoided, and the capture temperature of silver is only 950 °C, which is significantly lower than that of lead capture (1100–1200 °C). The energy consumption is significantly reduced, so the proposed process can accomplish the clean recovery of rare and precious metals in copper anode slime and promote the green development of the copper metallurgy industry.

Evidence of defect-induced broadband light emission from 2D Ag-Bi double perovskites grown at liquid-liquid interfaces.

Controlling the light emission spectra of low-dimensional hybrid organic-inorganic materials remains an important goal toward the implementation of these materials into real-world optoelectronic devices. In this study, we present evidence that the self-assembly of two-dimensional (2D) silver bismuth iodide double perovskite derivatives at the interface of aqueous and organic solutions leads to the formation of defects capable of modulating the light emission spectra of these materials. Through an analysis of the structural parameters used to explain the photoluminescence (PL) spectra of 2D perovskites, we show the light spectra emitted by (4-ammonium methyl)piperidinium (4-AMP) and (3-ammonium methyl)pyridinium (3-AMPy)-spaced AgBiI8 double perovskites formed through interfacial solution-phase chemistry differ qualitatively and quantitatively from thin film samples. We use previous results to propose the differences observed in the PL spectra of different material morphologies stem from equatorial iodide vacancy formation driven by the kinetics of self-assembly at the liquid-liquid interface. These results show the generality of these chemical physics principles in the formation of defect sites in solution-processed semiconducting nanomaterials, which could help enable their broad use in optoelectronic technologies.