SiS2 Research Articles

Mixed Electronic-Ionic Conductive Polymer Binder for Silicon-Based Solid-State Battery

Silicon has attracted extensive research attention in lithium-ion battery (LIB) field due to its high theoretical specific capacity (~3600 mAh/g) and cost-effectiveness. In recent years, silicon has emerged as a viable candidate for anode material for solid-state battery (SSB) technology. Similar to its application in LIBs, silicon utilizing in SSBs encounters challenges, such as significant volume variation (~300%) during cycling and poor cycling performance. In addition, the utilization of silicon in SSB faces another critical bottleneck in ionic conductivity due to the absence of liquid electrolyte. To address these challenges, various pioneering studies have explored potential solutions, including controlling the thickness of silicon anode to be below 150 nm,(1) fabricating electrodes with a combination of silicon and solid-state electrolyte (e.g, Garnet-type electrolyte(2) and sulfide electrolyte(3)), subjecting SSBs to a high pressure (10-50 MPa)(4).Here, we introduced an alternative approach to mitigate these challenges by designing anodes through incorporating silicon with mixed electronic-ionic conductive (MEIC) hierarchically ordered structure (HOS) polymer binders. These multifunctional HOS polymer binders effectively preserve the structural integrity of electrode materials, even when silicon materials experiences significant volume expansion and shrinkage during the charging-discharging process. Owing to establishments of covalent bonds between silicon surface and the polymer binders, the resulting SSBs exhibited excellent resilience and only required hand-tightening force (<1 ton) for operation. These polymer binders effectively maintained continuous electronic and ionic pathways within silicon-based anodes without the need of additional additives, such as carbon material and solid-state electrolytes. Utilizing these versatile polymer binders, the resultant SSBs featured an outstanding cycling performance over 100 cycles in full cells, with an average Coulombic efficiency exceeding 97%. Reference A. Song, W. Zhang, H. Guo, L. Dong, T. Jin, C. Shen and K. Xie, Advanced Energy Materials, 13, 2301464 (2023).W. Ping, C. Yang, Y. Bao, C. Wang, H. Xie, E. Hitz, J. Cheng, T. Li and L. Hu, Energy Storage Materials, 21, 246 (2019).M. Rana, Y. Rudel, P. Heuer, E. Schlautmann, C. Rosenbach, M. Y. Ali, H. Wiggers, A. Bielefeld and W. G. Zeier, ACS Energy Letters, 8, 3196 (2023).D. H. Tan, Y.-T. Chen, H. Yang, W. Bao, B. Sreenarayanan, J.-M. Doux, W. Li, B. Lu, S.-Y. Ham and B. Sayahpour, Science, 373, 1494 (2021).

[formula omitted] magnetism engineering in the low-buckled hexagonal SiS monolayer: A first-principles study

In this work, vacancy- and doped-induced magnetism engineering is investigated to functionalize the non-magnetic low-buckled hexagonal silicon sulfide (SiS) monolayer. This monolayer is an indirect gap semiconductor two-dimensional (2D) material with an energy gap of 2.20(3.02) eV obtained from the PBE(HSE06)-based calculations. Creating a single Si vacancy leads to a significant magnetization of SiS monolayer with the feature-rich half-metallic nature. Herein, a total magnetic moment of 1.89 μB is obtained and magnetic properties are produced mainly by S and Si atoms closest to the defect site. In contrast, single S vacancy preserves the non-magnetic nature inducing a band gap reduction of the order of 26.36%. n-type doping with P atom metalizes the monolayer, meanwhile As impurity leads to the emergence of the half-metallicity with a total magnetic moment of 1.00 μB. Similarly, this value is also obtained by p-doping using P and As atoms as dopants, where the diluted magnetic semiconductor nature is obtained. Moreover, doping with IA- (Na and K) and IIIA-group (Al and Ga) atoms is also proposed to engineer the magnetism in SiS monolayer. It is found that these impurities induce either half-metallic or diluted magnetic semiconductor behaviors with total magnetic moment between 0.99 and 1.00 μB. The electronic and magnetic properties are regulated mainly by the interactions between impurities and their neighbor S atoms, which modify the charge distribution in their outermost orbitals. In addition, the Bader charge analysis asserts that dopant atoms gain charge from the host monolayer when substituting S atom, meanwhile they act as charge loser — transferring charge to the host monolayer when doping at Si sublattice. The presented results may suggest efficient approaches to properly engineer SiS monolayer electronic and magnetic properties, making new 2D candidates for spintronic applications.

Comparative simulation analysis of μc Si:H and SnS BSF layers in CIGS solar cells

In this paper, we presented Cu(In1-xGax)Se2 (CIGS) based solar cells in which hydrogenated microcrystalline silicon (μc Si:H) and tin sulfide (SnS) are used as back surface field (BSF) layers. In CIGS thin film solar cell technology, thickness serves a crucial factor. Optimizing absorber thickness reduces the usage of scarce and expensive materials such as indium (In) and gallium (Ga) in CIGS cells. Integrating a heavily doped layer between the absorber and the back surface, known as the back surface field (BSF) layer, in solar cell design is a successful strategy for minimizing the thickness of the absorber layer. The suggested configuration utilizes μc-Si:H and SnS as the back surface field (BSF) layer. The buffer layer in this configuration employs less harmful InP instead of the typically utilized CdS layer. All the simulation work is performed using SCAP-1D simulation tool. The utilization of μc Si:H and SnS BSF layers yields optimized efficiencies of 31.51% and 31.01%, respectively. This simulation work demonstrates that use of a proper BSF layer is very effective not only in performance enhancement but also in reducing absorber material thickness.

Acidithiobacillus ferrooxidans Leaching of Silica-Sulfide Gold Ores from May-Hibey Deposits, Tigray, Ethiopia

Oxidative leaching is an inexpensive alternative to using chemical cyanide extraction methods for gold from low-grade gold sulfide. Oxidation of finely ground gold-bearing ore by Acidithiobacillus ferrooxidans was evaluated in terms of cell density, pH, and leaching efficiency of Fe and Au in shake flask experiments. The compositional and elemental analyses of the beneficiated ore were analyzed using XRD and EDXRF spectroscopy. The ore’s primary constituents are gold (4.356 mg/L), silicon, iron, and sulfur (62.456, 15.441, and 7.912 wt%, respectively). XRD spectra, the main phases of the concentrated ore, showed that the major components of the ore were quartz, syn, silicon sulfide, pyrite, and polymetallic elements such as silderenrite, gismondine, siderenikite, hematite, and syn. The experimental results, with Acidithiobacillus ferrooxidans bacteria and blank, were evaluated. The pH of the blank remained nearly constant, and the pH of the bioleached was occasionally lowered. The A. ferrooxidans strain always grew better throughout the bioleaching process. For the A. ferrooxidans strain, the cell density of cells reached a maximum of 90.00 × 106 cells/mL after the 11th week and decreased to 87.00 × 106 cells/mL after the 12th week. The decrease in cell density may be due to the presence of polymetallic elements such as Al, Cr, Ti, and Ni, leading to reduced metal tolerance of the A. ferrooxidans strain. In the A. ferrooxidans leaching process, the maximum total iron and gold extraction reached 92.16% (14.23 mg/L) and 99.97% (4.355 ppm), respectively, after the 11th week, and leaching tends to decrease up to 14 weeks, which may be due to the formation of secondary minerals. More research will be performed to optimize the procedure and leaching kinetic, examine the impact of metal content, and take into account the potential for bioleaching process pollution in addition to the amount of gold recovered.

Isolation of cubic Si3P4 in the form of nanocrystals.

This article describes an approach for synthesizing silicon phosphide nanoparticles with a defective zinc blende structure under mild conditions through thermal annealing of hydrogenated silicon nanoparticles with red phosphorus. The synthesized Si3P4 nanoparticles were analyzed using FTIR, XRD, electron diffraction, EDX, TEM, Raman spectroscopy, X-ray fluorescence spectrometry, and UV-vis spectrophotometry. For the isolated cubic Si3P4 phase, a cell parameter of a = 5.04 Å was determined, and the bandgap was estimated to be equal to 1.25 eV. Because of the nanoscale dimensions of the obtained Si3P4 nanoparticles, the product may exhibit several exceptional properties as a precursor for diffusion doping of wafers and as anode material for Li-ion batteries. A similar method with a hydrogenation step offers the possibility to obtain other compounds, such as silicon selenides, arsenides, and sulfides.

Nano Silicon Anode without Electrolyte Adding for Sulfide-Based All-Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLBs) employing silicon (Si) anode and sulfide electrolyte attract much attention, since they can achieve both high energy density and safety. For large-scale application, sheet-type Si anode matching sulfide based ASSLBs is preferred. Here, a LiAlO2 layer coated Si (Si@LiAlO2 ) is reported for sheet-type electrode. This electrode employs conventional slurry coating methods without adding any sulfide electrolyte. The effect of LiAlO2 coating on the electrochemical performance and morphology evolution of Si electrode is investigated. Since the high mechanical strength and ionic conductivity of LiAlO2 layer can sufficiently relieve the huge expansion of Si and promote the Li+ diffusion, the electrochemical performance is significantly enhanced. The Si@LiAlO2 electrodes deliver high coulombic efficiency exceeding 80% and hold considerable specific capacity of 1205mAhg-1 (150cycles, 0.33C). The Si@LiAlO2 | LiNi0.83 Co0.11 Mn0.06 O2 full-cells exhibit a high reversible capacity of 147mAhg-1 (0.28mAcm-2 ) and a considerable capacity retention of 80.2% (62cycles, 2.8mAcm-2 ). This work demonstrates promising practicability and provides a new route for the scalable preparation of Si electrode sheets for ASSLBs with extended lifespan.

Modifying nano-silicon with nano-antimony through molten salt electrolysis for superior lithium storage materials

The application of silicon to lithium-ion batteries (LIBs) remains a challenge due to the severe volume expansion effect of silicon. In this work, a nano Si-Sb bimetal is obtained by the molten salt electrolysis of mixture of silicon and antimony sulfide (Sb2S3). The uniform hybrid of antimony nanoparticles not only prevents the agglomeration of silicon but also selectively decomposes the electrolyte additives and alleviates the rupture of SEI effectively, which can mitigate the volume expansion of silicon. When used as a negative electrode for LIBs, the Si-Sb bimetallic electrode delivers a reversible capacity of 1524 mAh/g after 100 cycles at a current density of 1 A/g. Even at 3 A/g, the reversible capacity is as high as 1062 mAh/g after 200 cycles. This work offers a new way for the fabrication of Si-based alloy anodes through using molten salt electrolysis.

Polypyrrole embedded in nickel-cobalt sulfide nanosheets grown on nickel particles passivated silicon nanowire arrays for high-performance supercapacitors

Metal sulfide-based composites have been considered as promising electrode materials for energy storage, but the fabrication process of such composites is complicated and requires a multistep hydrothermal treatment. Considering the integration with the silicon-based microelectronics, electrode materials prepared from 3D silicon and metal sulfide are needed. In this work, a hierarchical multi-shelled Ppy-NCS@Ni@SiNWs electrode was successfully developed with a simple, clean and low-cost method, where polypyrrole (Ppy) and nickel–cobalt sulfide (NCS) were co-electrodeposited on nickel particles passivated silicon nanowire arrays (SiNWs). Benefiting from the large surface of SiNWs, high conductivity of nickel passivation layer and the synergy effect between Ppy and NCS including large capacity, hydrophilic surface and high mechanical strength, the as-prepared electrode demonstrated a remarkable specific capacitance (1602 F g-1 at 1 A g−1), an excellent rate capacity (1348 F g-1 at 30 A g−1) and a high cycling stability (91.6 % of initial capacitance after 10,000 cycles). Additionally, a solid asymmetric supercapacitor was fabricated by employing Ppy-NCS@Ni@SiNWs as the positive electrode, which realized a superior energy density of 131.322 Wh kg−1 at an outstanding power density of 1.44 kW kg−1. The findings demonstrate that the hybrid composite of conductive polymer and metal sulfide grown on 3D silicon has enormous potential for energy storage materials.

Silicon disulfide for high-performance Li-ion batteries and solid-state electrolytes

A layered silicon disulfide (SiS2) was synthesized on a large-scale via a solid–gas phase reaction and applied as an anode material for Li-ion batteries and solid-state electrolytes for all-solid-state batteries.

Obtaining new types of compounds between silicon and cadmium sulfide

The n+CdS-nCdS-nSi+ structures were obtained and their volt-ampere characteristics at different temperatures were studied. From the dependence of the volt-ampere characteristic it is shown that the sublinear and quadratic section of these structures has a section of current growth with voltage. It is determined that the n+CdS-nCdS-nSi+structures in the current flow direction at low illumination levels work as an injection photodiode. And these structures under laser illumination with λ=0.625 μm and power P=1.2 μW/cm2 have spectral sensitivity 2042 A/W, bias voltage 10 V. At irradiation by white light with energy W=3.6-10μW∙s it has integral sensitivity ≈21 A/I’m (2310 A/W) at bias voltage U=10V.

STUDYING THE PROCESS OF SULFIDING AN OXIDIZED COPPER ORE BY THE METHOD OF MECHANOCHEMICAL ACTIVATION

In recent years, a new direction has appeared in metallurgical processes according to which the processing of concentrates is carried out by a combination of mechanical and metal-thermal methods of recovery. This contributes to the intensification of further redox processes and the production of fundamentally new modified products. In the case of enrichment of oxidized copper minerals, a more acceptable type of surface activation are mechanical activation processes with a combination of added reagents. It is established that sulfiding of oxidized copper minerals with elemental sulfur, silicon and sodium sulfides proceeds actively. As a result of the research, the optimal modes of sulfiding oxidized copper ores are determined. As a result of comprehensive research, a technology has been developed for processing oxidized copper minerals in a mill by sulfiding and subsequent flotation.

Obtaining new types of compounds between silicon and cadmium sulfide

The n+CdS-nCdS-nSi+ structures were obtained, and their volt-ampere characteristics at different temperatures were studied. The dependence of the volt-ampere characteristic shows that the sublinear and quadratic section of these structures has a section of current growth with voltage. It is determined that the n+CdS-nCdS-nSi+ structures in the current flow direction at low illumination levels work as an injection photodiode. And these structures under laser illumination with λ=0.625 μm and power P=1.2 µW/cm2 have spectral sensitivity 2042 A/W, bias voltage 10 V. At irradiation by white light with energy W=3.6-10µW·s it has integral sensitivity ≈21 A/I'm (2310 A/W) at bias voltage U=10V.

Engineering graphitic carbon nitride for next-generation photodetectors: a mini review.

Semiconductor photodetectors, as photoelectric devices using optical-electrical signal conversion for detection, are widely used in various fields such as optical communication, medical imaging, environmental monitoring, military tracking, remote sensing, etc. Compared to the conventional photodetector materials including silicon, III-V semiconductors and metal sulfides, graphitic carbon nitride (g-C3N4) as a metal-free polymeric semiconductor, has many advantages such as low-price, easy preparation, efficient visible light response, and relatively good thermal stability. In the meantime, the polymer characteristics also endow the g-C3N4 with good mechanical properties. Apart from being used for photo(electro)catalysts during the past decades, the potential use of g-C3N4 in photodetectors has attracted great research interests very recently. In this review, we first briefly introduce the structure and properties of g-C3N4 and the key performance parameters of photodetectors. Then, combining the very recent progress, the review focuses on the active materials, fabrication methods and performance enhancement strategies for g-C3N4 based photodetectors. The existing challenges are discussed and the future development of g-C3N4 based photodetectors is also forecasted.

Electronic Properties and Electrocatalytic Water Splitting Activity for Precious-Metal-Adsorbed Silicene with Nonmetal Doping.

Since nonmetal (NM)-doped two-dimensional (2D) materials can effectively modulate their physical properties and chemical activities, they have received a lot of attention from researchers. Therefore, the stability, electronic properties, and electrocatalytic water splitting activity of precious-metal (PM)-adsorbed silicene doped with two NM atoms are investigated based on density functional theory (DFT) in this paper. The results show that NM doping can effectively improve the stability of PM-adsorbed silicene and exhibit rich electronic properties. Meanwhile, by comparing the free energies of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) intermediates of 15 more stable NM-doped systems, it can be concluded that the electrocatalytic water splitting activity of the NM-doped systems is more influenced by the temperature. Moreover, the Si–S2–Ir-doped system exhibits good HER performance when the temperature is 300 K, while the Si–N2–Pt-doped system shows excellent OER activity. Our theoretical study shows that NM doping can effectively promote the stability and electrocatalytic water splitting of PM-adsorbed silicene, which can help in the application of silicene in electrocatalytic water splitting.

Interactive effects of hydrogen sulphide and silicon enhance drought and heat tolerance by modulating hormones, antioxidant defence enzymes and redox status in barley (Hordeum vulgare L.).

Recent changes in climate have reduced crop productivity throughout much of the world. Drought and heat stress, particularly in arid and semi-arid regions, have seriously affected barley production. This study explored the separate and interactive effects of silicon (Si) and hydrogen sulphide (H2 S) on plant growth and mitigation of the adverse effects of heat stress (DS) and drought stress (HS) in a barley pot experiment. The impacts of simultaneous DS + HS were more severe than individual stresses due to increased ROS production, malondialdehyde (MDA) content and higher electrolyte leakage (EL), thereby leading to reduced water, protein and photosynthetic pigment content. Exogenously applied Si and H2 S alleviated the DS-, HS- and DS + HS-induced effects on barley by reducing ROS production, MDA and EL. A single application of H2 S or Si + H2 S increased plant biomass under all stress conditions, which can be ascribed to higher Si accumulation in barley shoots. A single application of Si or H2 S significantly increased plant biomass. However, Si + H2 S was the most effective treatment for metabolite accumulation and elevating activity of antioxidant enzymes to prevent toxicity from oxidative stress. This treatment also modulated osmolyte content, enhanced antioxidant activity and regulated the stress signalling-related endogenous hormones, abscisic acid (ABA) and indole acetic acid (IAA). Exogenous treatments regulated endogenous H2 S and Si and resulted in higher tolerance to individual and combined drought and heat stress in barley.

Exogenous silicon and hydrogen sulfide alleviates the simultaneously occurring drought stress and leaf rust infection in wheat

Silicon (Si) and hydrogen sulfide (H2S) are known to enhance plant defense against multiple stresses. Current study was conducted to investigate the application of Si and H2S alone as well as in combination, improved physiological resilience of wheat plants to drought stress (DS) and pathogen-Puccinia triticina (Pt) infection. We aimed to increase the wheat plant growth and to enhance the DS tolerance and Pt resistance with the concurrent applications of H2S and Si. In the first experiment, we selected the best growth enhancing concentration of H2S (0.3 mM) and Si (6 mM) to further investigate their tolerance and resistance potential in the pot experiment under DS and pathogen infection conditions. The obtained results reveal that DS has further increased the susceptibility of wheat plants to leaf rust pathogen infection while, the sole application of Si and the simultaneous exogenous treatments of H2S + Si enhanced the plant growth, decreased disease incidence, and significantly improved tolerance and defense mechanisms of wheat under individual and interactive stress conditions. The exogenous treatment of H2S + Si improved the growth criteria, photosynthetic pigments, osmoprotectants, and defense related enzyme activities. The same treatment also reinforced the endogenous H2S, Si, ABA and SA contents while decreased the disease incidence and oxidative stress indicators under individual and combined stress conditions. Overall, results from this study presents the influence of combined drought and P. triticina stress in wheat and reveal the beneficial impacts of concurrent exogenous treatment of H2S + Si to mitigate the drought and pathogen (P. triticina) induced adverse effects.

Synthesis of Silicon Sulfide by Using CS2 Gas

Silicon sulfide (SiS2) was synthesized from Si, SiC, Si3N4, and a eutectic Al-Si liquid. An Ar-CS2 gas mixture, after bubbling through liquid CS2, was passed over pulverized Si, SiC, Si3N4, or a eutectic Al-Si alloy liquid. White, needle-shaped SiS2 was precipitated as a single phase on the colder downstream surface when Si powder in a SiO2 liner was heated over 1273 K. This deposition mechanism involves a reaction between Si and CS2 to form SiS2, with the vaporization of SiS(g) and deposition as SiS2(s) from SiS(g) and S2(g). Quartz was unaffected by the reaction gases. Notably, Si, SiC, Si3N4, and the eutectic Al-Si liquid were found to be suitable sources for SiS2 synthesis, although this was suppressed owing to Al2S3 formation on the latter.

Приоритетные факторы риска питьевой воды систем централизованного питьевого водоснабжения, формирующие негативные тенденции в состоянии здоровья населения

Our research object was long-term dynamics of parameters describing drinking water from centralized water supply systems and additional cases of health disorders among population in Russia directly caused by low-quality drinking water. Our research goal was to perform hygienic assessment of priority risk factors related to drinking water and potential health disorders that could be caused by them. Our research technique was hygienic analysis of drinking water parameters as per data taken from the federal statistical form No. 18 entitled «Data on sanitary situation in a RF region» over 2000–2019, the federal information fund of social and hygienic monitoring over 2012–2019, and calculation of associated health disorders as per MG 5.1.0095–14. Specific weight of centralized water supply sources that didn’t conform to sanitary-epidemiologic requirements decreased by 4.7 % over 2000–2019 and amounted to 14.9 %. Over the last 20 years there has been a descending trend in specific weight of water samples taken from centralized water supply sources that don’t conform to sanitary requirements as per sanitary-chemical parameters (by 2.7 %) and microbiological parameters (by 4.8%). Over 2000–2019, specific weight of water distribution networks not conforming to sanitary-epidemiologic requirements decreased by 10.7 % and amounted to 15.9 % in 2019. Over the last 20 years there has been an increase in quality of drinking water taken from centralized distribution networks. Specific weight of water samples from centralized distribution networks not conforming to sanitary requirements as per microbiological and sanitary-chemical parameters fell by 6.7 % and 7.9 % respectively. In 2012–2019 in the RF hygienic parameters of drinking water quality were the most violated as per contents of bromine, silicon, chlorine, iron, sodium, lithium, magnesium, manganese, chloroform, boron, strontium, sulfides, and hydrogen sulphide. Overall, in the RF in 2019 more than 1.66 million cases of digestive diseases, cardiovascular diseases, diseases of skin and subcutaneous tissue, and other health disorders were directly related to drinking water being contaminated with chemicals and microbiological agents; it was by 13.3 % lower than in 2012 regarding morbidity associated with drinking water quality. Priority risk factors were chlorine, chlorine organic compounds (COC), ammonia, iron, manganese, arsenic, nickel, copper, boron, magnesium, and other compounds.

Priority risk factors related to drinking water from centralized water supply system that create negative trends in population health

Our research object was long-term dynamics of parameters describing drinking water from centralized water supply systems and additional cases of health disorders among population in Russia directly caused by low-quality drinking water. Our research goal was to perform hygienic assessment of priority risk factors related to drinking water and potential health disorders that could be caused by them. Our research technique was hygienic analysis of drinking water parameters as per data taken from the federal statistical form No. 18 entitled «Data on sanitary situation in a RF region» over 2000–2019, the federal information fund of social and hygienic monitoring over 2012–2019, and calculation of associated health disorders as per MG 5.1.0095–14. Specific weight of centralized water supply sources that didn’t conform to sanitary-epidemiologic requirements decreased by 4.7 % over 2000–2019 and amounted to 14.9 %. Over the last 20 years there has been a descending trend in specific weight of water samples taken from centralized water supply sources that don’t conform to sanitary requirements as per sanitary-chemical parameters (by 2.7 %) and microbiological parameters (by 4.8%). Over 2000–2019, specific weight of water distribution networks not conforming to sanitary-epidemiologic requirements decreased by 10.7 % and amounted to 15.9 % in 2019. Over the last 20 years there has been an increase in quality of drinking water taken from centralized distribution networks. Specific weight of water samples from centralized distribution networks not conforming to sanitary requirements as per microbiological and sanitary-chemical parameters fell by 6.7 % and 7.9 % respectively. In 2012–2019 in the RF hygienic parameters of drinking water quality were the most violated as per contents of bromine, silicon, chlorine, iron, sodium, lithium, magnesium, manganese, chloroform, boron, strontium, sulfides, and hydrogen sulphide. Overall, in the RF in 2019 more than 1.66 million cases of digestive diseases, cardiovascular diseases, diseases of skin and subcutaneous tissue, and other health disorders were directly related to drinking water being contaminated with chemicals and microbiological agents; it was by 13.3 % lower than in 2012 regarding morbidity associated with drinking water quality. Priority risk factors were chlorine, chlorine organic compounds (COC), ammonia, iron, manganese, arsenic, nickel, copper, boron, magnesium, and other compounds.

Copper Iron Sulfide Nanocrystal‐Bulk Silicon Heterojunctions for Broadband Photodetection

AbstractThis study describes the optoelectronic characteristics of CuFeS2/Si nanocrystal/bulk heterojunctions. These heterojunctions show a strong photocurrent response under ambient conditions upon excitation from a wide optical spectrum, from 460 to 2200 nm. The devices comprise of a heterojunction formed between heavily doped n‐type silicon (1–100 Ω cm) and copper iron sulfide (CuFeS2) nanocrystal films. Over the spectral range 460–2200 nm the device shows a fast response (20 µs at NIR wavelengths), along with responsivity and detectivity of 4.68 mA W−1 and 5.29 × 109 Jones at 1900 nm wavelength. The photocurrent is further observed to be a nonlinear function of power. These properties of the devices are discussed in terms of a defect filling mechanism. Besides their regular photoresponse described above, the devices also exhibit a slower photothermal response, allowing these to also sense hot objects (450 K; excess 6 mW incident onto the device) within the focal plane, thereby extending the useful sensing range of the devices deeper into the infrared.