Near-infrared Region Research Articles

Ultra-broadband and wide-angle plasmonic light absorber based on all-dielectric gallium arsenide (GaAs) metasurface in visible and near-infrared region

High-performance and cost-effective broadband light absorbers are crucial for various optical applications, including solar energy harvesting, thermophotovoltaic systems, and integrated photoelectric devices. In this study, an ultra-broadband and wide-angle plasmonic light absorber (PLA) based on an all-dielectric gallium arsenide (GaAs) metasurface in the visible and near-infrared regions is proposed and numerically investigated. The unit-cell of the proposed PLA is consisted of all-dielectric GaAs cylinder resonator (CR) adhered on an ultra-thin GaAs spacer layer backed with a tungsten (W) substrate. Numerical simulation results show that the absorption peak of the proposed PLA is up to 99.85 %, 99.9 % and 99.98 % at 0.452 μm, 0.712 μm and 1.596 μm, respectively. In addition, the ultra-broadband strong absorption of over 90 % also can be achieved from 0.39 μm to 2.09 μm with a relative bandwidth of 137.1 %. The ultrabroadband strong absorption of the proposed PLA is further demonstrated by the equivalent circuit model (ECM), which displays excellent agreement with the results of the full-wave numerical simulation performed using the finite element method (FEM). The simulated electromagnetic (EM) field distributions reveal that the ultra-broadband strong absorption of the designed PLA is mainly from the excited propagating surface plasmon (PSP), located surface plasmon (LSP), cavity resonance modes combined with coupling effect between adjacent CRs. The proposed PLA is also polarization-insensitive and wide incident angles for both transverse electric (TE) and transverse magnetic (TM) modes. The absorption properties of the designed PLA can be adjusted by varying geometric parameters of the unit-cell. The PLA achieves a remarkable short-circuit current density of over 64.75569 mA/cm2 and exhibits nearly perfect solar energy trapping due to the effective coupling of multiple resonances, resulting in enhanced photovoltaic performance. Thus, the proposed PLA can be potential application in the photodetectors, thermal imaging, and solar energy harvesting devices.

Highly Efficient DSSCs Sensitized Using NIR Responsive Bacteriopheophytine-a and Its Derivatives Extracted from Rhodobacter Sphaeroides Photobacteria.

Employing naturally extracted dyes and their derivatives as photosensitizers towards the construction of dye-sensitized solar cells (DSSCs) has been recently emerging for establishing sustainable energy conversion devices. In this present work, Rhodobacter Sphaeroides Photobacteria (Rh. Sphaeroides) was used as a natural source from which Bacteriopheophytine-a (Bhcl) dye was extracted. Further, two cationic derivatives of Bhcl, viz., Guanidino-bacteriopheophorbide-a (Gua-Bhcl) and (2-aminoethyl)triphenylphosphono-bacteriopheophorbide-a (2AETPPh-Bhcl) were synthesized. The thus obtained Bhcl, Gua-Bhcl and 2AETPPh-Bhcl were characterized using liquid chromatography-mass spectrometry (LC-MS) and their photophysical properties were investigated using excitation and emission studies. All three near-infrared (NIR) responsive dyes were employed as natural sensitizers towards the construction of DSSC devices, using platinum as a photocathode, dye-sensitized P25-TiO2 as a photoanode and I-/I3- as an electrolyte. DSSCs fabricated using all three dyes have shown reasonably good photovoltaic performance, among which 2AETPPh-Bhcl dye has shown a relatively higher power conversion efficiency (η) of 0.38% with a short circuit photocurrent density (JSC) of 1.03 mA cm-2. This could be attributed to the dye's natural optimal light absorption in the visible and NIR region and uniform dispersion through the electrostatic interaction of the cationic derivatives on the TiO2 photoanode. Furthermore, the atomic force microscopy studies and electrochemical investigations using cyclic voltammetry, electrochemical impedance spectroscopy and Bode's plot also supported the enhancement in performance attained with 2AETPPh-Bhcl dye.

Photothermal therapy of tuberculosis using targeting pre-activated macrophage membrane-coated nanoparticles.

Conventional antibiotics used for treating tuberculosis (TB) suffer from drug resistance and multiple complications. Here we propose a lesion-pathogen dual-targeting strategy for the management of TB by coating Mycobacterium-stimulated macrophage membranes onto polymeric cores encapsulated with an aggregation-induced emission photothermal agent that is excitable with a 1,064 nm laser. The coated nanoparticles carry specific receptors for Mycobacterium tuberculosis, which enables them to target tuberculous granulomas and internal M. tuberculosis simultaneously. In a mouse model of TB, intravenously injected nanoparticles image individual granulomas in situ in the lungs via signal emission in the near-infrared region IIb, with an imaging resolution much higher than that of clinical computed tomography. With 1,064 nm laser irradiation from outside the thoracic cavity, the photothermal effect generated by these nanoparticles eradicates the targeted M. tuberculosis and alleviates pathological damage and excessive inflammation in the lungs, resulting in a better therapeutic efficacy compared with a combination of first-line antibiotics. This precise photothermal modality that uses dual-targeted imaging in the near-infrared region IIb demonstrates a theranostic strategy for TB management.

Switchable large-angle beam splitter based on a continuous metasurface in the near-infrared region

Metasurface-based beam splitters with broadband and high efficiency are highly desirable in various optical and photonic applications. In this paper, we theoretically propose a switchable equal power beam splitter with large beam splitting angle based on a continuous metasurface by integrating the vanadium dioxide (VO2). Utilizing the phase change characteristics of VO2, the beam splitter can be thermally switched between transmission and reflection modes in the near-infrared region. Moreover, the theoretical calculation value of the splitting angle matches well with the simulation result. And the conversion efficiencies of both transmission and reflection modes reach up to ∼100% in a broadband wavelength range. In addition, we discuss the influences of related geometrical parameters on the performance of beam splitter in detail. Our proposed switchable power beam splitter may have potential applications in integration and miniaturization of modern optical devices.

An Ir (III) complex with multiphoton absorption in the near-infrared region as a probe for mtDNA-specific recognition and mitochondrial imaging

The multiphoton absorbing (MPA) materials have been extensively investigated due to their crucial merits of long wavelength excitation and short wavelength emission, of which the organometallic complexes are the most promising but still challenging candidates for developing efficient MPA materials. Herein, a novel cyclometallated iridium complex (abbreviated as SQ) is reported as a multiphoton absorption phosphorescent probe, which is constructed by coordinating the central metal Ir with diethoxyphenyl terpyridine, phenyl pyridine and SCN ligands. The single crystal of SQ exhibits a twisted octahedral structure that can avoid phosphorescence quenching caused by π-π stacking, and the push-pull electron effect of the ligand endows SQ with excellent nonlinear optical (NLO) properties under near-infrared excitation. As a result, two-photon imaging with deep tissue penetration depths is realized at the excitation wavelength of 750 nm. Meanwhile, the planar conjugated structure of diethoxyphenyl terpyridine facilitates the insertion of SQ into base pairs of mitochondrial DNA (mtDNA), thus limiting the intramolecular rotation. Consequently, the emission intensity of the SQ solution enhanced approximately 10-fold after mtDNA was introduced, which led to mtDNA-specific recognition. Our work proves a new way of designing a phosphorescence probe that can specifically identify mtDNA, thus realizing dynamic monitoring of mitochondria.

Dithienopyran-based narrow-bandgap donor polymers: Unveiling the potential for semitransparent organic solar cells with enhanced NIR absorption

Semitransparent organic solar cells (ST-OSCs) have recently received considerable attention in the field of photovoltaics owing to their great potential in applications such as building-integrated photovoltaics, self-powered greenhouses, and vehicle coatings. Because the near-infrared (NIR) region is an invisible region whose photon content is higher than that of the visible region, it is preferable to apply photoactive materials with narrow bandgaps in ST-OSCs. Tremendous efforts have been made to develop narrow-bandgap non-fullerene acceptors, however, donor polymers with NIR absorption ability for efficient ST-OSCs have rarely been reported. In this study, two novel narrow-bandgap donor polymers, PDTP-TBT and PDTTP-TBT, are designed and synthesized. Both polymers exhibit strong NIR absorption and high transmittance in the visible region, suggesting their potential for use in ST-OSCs. An opaque OSC with a PDTTP-TBT-based photoactive layer achieves a higher power conversion efficiency (PCE) of 8.87% than a PDTP-TBT-based OSC (PCE of 3.65%) due to its better charge transport characteristics. Furthermore, an ST-OSC using PDTTP-TBT-based blend film exhibits a PCE of 6.72%, average visible transmittance of 43.9%, and light utilization efficiency of 2.95%.

High-performance broadband photodetector based on PtSe2/MoS2 heterojunction from visible to near-infrared region

High-performance broadband photodetector based on PtSe2/MoS2 heterojunction from visible to near-infrared region

Efficient Photothermal Sensor Based on Coral-Like Hollow Gold Nanospheres for the Sensitive Detection of Sulfonamides.

Gold nanoparticles (AuNPs), universally regarded as colorimetric signal reporters, are widely employed in lateral flow immunoassays (LFIAs). However, it is difficult for AuNPs-LFIA to achieve a wide range and sensitive detection. Herein, novel coral-like hollow gold nanospheres (CHGNPs) are synthesized. The growth of gold nanospheres can be regulated to obtain a multibranched and hollow construction. The obtained CHGNPs possess intense broadband absorption across the visible to near-infrared region, exhibiting a high molar extinction coefficient of 14.65×1011 M-1 cm-1 and a photothermal conversion efficiency of 79.75%. Thus, the photothermal/colorimetric dual-readout LFIA is developed based on CHGNPs (CHGNPs-PT-LFIA and CHGNPs-CM-LFIA) to effectively improve the detection sensitivity and broaden the detection range in regard to sulfonamides (SAs). The limits of detection of the CHGNPs-PT-LFIA and CHGNPs-CM-LFIA reached 1.9 and 2.8pgmL-1 for the quantitative detection of sulfaquinoxaline, respectively, which are 6.3-fold and 4.3-fold lower than that of the AuNPs-LFIA. Meanwhile, the CHGNPs-PT-LFIA broadened the detection range to three orders of magnitude, which ranged from 2.5 to 5000 pg mL-1 . The synthesized photothermal CHGNPs have been proven effective in improving the performance of the LFIA and provide a potential option for the construction of sensing platforms.

Evaluation of pH and Optical Properties of Dual Rinse HEDP Irrigating Solution

This study investigates the pH values and optical characteristics of Dual Rinse HEDP, either independently or combined with sodium hypochlorite (NaOCl), and compares them to other irrigants used in endodontics. The solutions used in this study were commercially acquired and prepared, followed by pH measurements using a pH meter and spectral analysis using UV/Vis spectrophotometry in specified wavelengths of the ultraviolet (UV) C (190–280 nm), UVB (281–315 nm), UVA (316–400 nm), visible light (VL) (401–780 nm), and near-infrared (NIR) spectra (781–1100 nm). The pH analysis revealed alkaline values for NaOCl, EDTA, Dual Rinse HEDP, and the HEDP + NaOCl combination, an acidic value for citric acid, and nearly neutral values for chlorhexidine and distilled water. Spectral analysis revealed the notable absorption characteristics of endodontic irrigants. In the UV range, all solutions exhibited higher absorption values to water (p < 0.05), with Dual Rinse HEDP resembling EDTA and citric acid, and HEDP + NaOCl resembling NaOCl. The NIR region highlights absorption peaks around 975 nm for all solutions, including NaOCl and Dual Rinse HEDP + NaOCl, suggesting potential applications in laser-activated irrigation. This study provides comprehensive insights into the pH and optical features of endodontic irrigants, emphasizing their potential roles in enhancing disinfection strategies and optimizing laser-activated irrigation protocols.

Efficient wide-spectrum one-dimensional MWO4 (M = Mn, Co, and Cd) photocatalysts: Synthesis, characterization and density functional theory study

Broadening the absorption region to near-infrared (NIR) light is critical for the photocatalysis due to the larger proportion and stronger penetration of NIR light in solar energy. In the present paper, one-dimensional (1D) MWO4 (M = Mn, Co, and Cd) materials synthesized by electrospinning technique, were studied by combining the density functional theory (DFT) with experiment results, which possessed the enhanced light absorption capability within the range of 200–2000 nm. It was proved that in the ultraviolet–visible (UV–Vis) region, the absorption bands of CoWO4 and MnWO4 samples were attributed to the metal-to-metal charge transfer mechanism, while the absorption of CdWO4 sample may be referable to the ligand-to-metal charge transfer mechanism. In the near-infrared (NIR) region, the absorption of CoWO4 and MnWO4 primarily originated from the d-d orbital transitions of Mn2+ and Co2+. The photocatalytic experimental results showed that the degradation rates for bisphenol A (BPA) over CoWO4, MnWO4, and CdWO4 photocatalysts under UV–Vis/NIR light irradiation for 140 min/12 h were 78.8 %/75.9 %, 23.8 %/21.3 %, 12.8 %/8.7 %, respectively. This research offers the novel insights into the precise construction of tungstate catalytic systems and contributes to the advancement of UV–Vis–NIR full spectrum photocatalytic technology, and lays a foundation for a cleaner and more environmental-friendly future.

Application of Infrared Spectroscopy in the Identification of Fallen Trees from the Amazon Rainforest (Myristicaceae)

Abstract The infrared spectrum carries the so-called fingerprint of a plant, a characteristic that can help the identification of wood from an integrative perspective. Fourier-transform near-infrared spectroscopy (FT-NIRS) was evaluated for its potential use in the taxonomic identification of natural fallen trees from the Amazon rainforest (Myristicaceae). Trees found on the forest floor (Amazonas, Brazil) were surveyed, and eight individuals were selected for the study. The material was removed from the trunk for anatomical identification based on xylem structure and obtaining NIR spectra (10,000 to 4,000 cm-1). A total of 1,080 spectra were collected and used in the multivariate analysis. Absorption bands in the NIR region and chemometrics (calibration models) were used to interpret the spectra, which indicated similarity trends at the genus and species levels. Linear discriminant analysis (LDA) was able to differentiate Iryanthera ulei and Virola (five species), which were misclassified in the field as a single species (Virola sp.). The accuracy of the results obtained by chemometric models (LDA 7 and 14) indicates the robustness of NIR spectroscopy, which can be used as a new tool in the integrative taxonomy of plant material from tropical forests that are difficult to identify and can analyzing many tests quickly and securely. Study Implications: The taxonomic identification of natural fallen trees found on the floor of tropical forests is quite complex given the lack of flowers, fruits, and leaves in field collection. Fourier-transform near-infrared spectroscopy demonstrated its capability to distinguish between wood samples from fallen trees belonging to the Myristicaceae family. The chemometric model successfully discriminated the samples, which had been erroneously lumped together in the field under the single species designation of Virola sp. This technique has been previously overlooked for providing differentiation. Our study highlights its efficacy to address misclassifications and allow taxonomic identification.

Highly sensitive fluorescence turn-OFF and reversible chemical sensor for Hg2+ ion based on pyrene appended 2-thiohydantoin

A novel fluorometric chemical sensor (PY-2TH) based on 2-thiohydantoin (2TH) in conjugation with pyrene (PY) was designed by facile one-pot Knoevenagel condensation reaction and explored for the sensitive and selective detection of Hg2+ ion in solution and solid state methods. Different analytical techniques like NMR and LC-MS concomitantly confirmed the structure of PY-2TH. Absorption and emission studies demonstrate positive solvatochromic effects indicating intramolecular charge transfer in polar solvents. PY-2TH exhibits unprecedented selectivity for detecting Hg2+ ions in tetrahydrofuran (THF) through turn-OFF fluorescence with 90% decrease in the emission intensity with a limit of detection (LOD) of ∼4.4 ppb. The mechanistic investigation through NMR and optical studies confirm the formation of a 2:1 complex between PY-2TH and Hg2+. Thin films of PY-2TH exhibits the J-aggregate formation in the solid state leading to a shift in the emission towards the near-infrared region. Further, we have demonstrated the applicability of PY-2TH for detection of Hg2+ ions and fluorescence imaging in live Zebrafish larvae and the toxicological effects are explored. Cytotoxic evaluation on Zebrafish larval cells revealed that PY-2TH is found to be non-toxic. Detailed analysis demonstrate the potential of PY-2TH for ultra-sensitive Hg2+ ion detection and removal in aqueous environments, highlighting its applicability for identification of metal contamination in live organisms and environmental toxicity.

Au nanoparticles decorated SrTiO3−x hollow structure for plasmatic enhanced hydrogen production in UV–visible and near-infrared region

Designing photocatalysts with a broad reaction to sunlight is crucial for efficient clean energy conversion. However, most catalysts reported so far can only respond to UV and visible light for photocatalysis, neglecting the utilization of near-infrared light, which accounts for almost 50 % of sunlight. In this study, we obtained Au nanoparticles (NPs) decorated porous hollow SrTiO3 material rich in oxygen defects using an acid etching-assisted hydrothermal method. The formation of a Schottky heterojunction between Au and SrTiO3−x with matched Fermi levels enhances the electron transfer ability of SrTiO3−x. Additionally, Au NPs exhibit two types of surface plasma resonance (SPR) effects at 480 nm (transverse SPR) and 800 nm (longitudinal SPR in the near-infrared region) by absorbing specific photons emitted by SrTiO3−x. The "hot" electrons of the photoexcited SPR state can be further injected into the CB of SrTiO3−x. Furthermore, the local electromagnetic field around the SPR-enhanced Au NPs effectively promotes the excitation and transfer kinetics of photoelectrons, allowing more "hot" electrons to participate in the photocatalytic reaction. Besides, the unique hollow porous structure of the catalyst ensures multiple reflections of sunlight within SrTiO3−x. As a result, the hydrogen production efficiency of Au-SrTiO3−x under near-infrared (NIR) and UV–vis-NIR light irradiation reaches 850 and 3206 μmol h−1g−1, with apparent quantum efficiency of 6.4 % and 7.2 % at 820 nm and 420 nm, respectively. The possible photocatalytic mechanism was proposed based on thorough systematic experimental analysis and theoretical calculations.

Iron Complexes as Potential Carriers of Diffuse Interstellar Bands: The Photodissociation Spectrum of Fe+(H2O) at Optical Wavelengths.

The fullerene ion C60+ is the only carrier of diffuse interstellar bands (DIBs) identified so far. Transition-metal compounds feature electronic transitions in the visible and near-infrared regions, making them potential DIB carriers. Since iron is the most abundant transition metal in the cosmos, we here test this idea with Fe+(H2O). Laboratory spectra were obtained by photodissociation spectroscopy at 80 K. Spectra were modeled with the reflection principle. A high-resolution spectrum of the DIB standard star HD 183143 served as an observational reference. Two broad bands were observed from 4120 to 6800 Å. The 4120-4800 Å band has sharp features emerging from the background, which have the width of DIBs but do not match the band positions of the reference spectrum. Calculations show that the spectrum arises from a d-d transition at the iron center. While no match was found for Fe+(H2O) with known DIBs, the observation of structured bands with line widths typical for DIBs shows that small molecules or molecular ions containing iron are promising candidates for DIB carriers.

High‐Efficiency Near‐Infrared OLED Enabled by Exciplex‐Forming Hosts and a New Organic Fluorescent Emitter

AbstractTwo blends comprising new dicyanopyrazine‐based acceptors (m‐CN and p‐CN) and a carbazole‐based donor CPTBF are explored for exciplex formation. The CPTBF:m‐CN and CPTBF:p‐CN blends show the signature red‐shifted emission together with the delayed fluorescence observed in time‐resolved measurement, manifesting the characteristics of thermally activated delayed fluorescence (TADF). The electroluminescence (EL) device employing CPTBF:m‐CN (CPTBF:p‐CN) blend as the emitting layer (EML) achieved an EQE of 5.22% (2.05%) with the EL λmax centered at 607 nm (625 nm). The exciplex excitons can be efficiently extracted by a new benzobisthiadiazole‐based near‐infrared (NIR) emitter DCzPBBT, where a device is configured with CPTBF:m‐CN: (5 wt.%) DCzPBBT as the EML to achieve a high EQE of 5.32% and an EL λmax 758 nm. Further increase of the doping concentration to 10 wt.% of DCzPBBT exhibits a bathochromic shifted EL λmax to 772 nm with 94% spectral coverage in the NIR (>700 nm) region, while the device EQE retains at 4.06%. The superior device performance stems from the highly efficient energy transfer between the exciplex‐forming host and NIR dopant together.

Mapping weed infestation in maize fields using Sentinel-2 data

Weed management in maize farms is a time-specific activity and requires timely detection of weed infestations. The challenge to early detection of weeds is that many dicotyledonous crops and broad-leaved weeds often display similar reflectance profile in the early growth stage and requires hyperspectral data to detect them. However, the advent of Sentinel-2 sensor series, with enhanced spectral configuration featuring red-edge bands that are known for species-level discrimination of plants, presents an affordable opportunity to detect weeds using multispectral data. The present study explores the question of whether Sentinel-2 sensor with its advanced spectral configuration can differentiate weeds from maize (Zea mays) in the early growth stages of maize. The study recorded 165 GPS points of weeds, maize, and mixed class in six maize farms during the early stages of maize growth. These GPS points were overlaid on Sentinel-2 images acquired within two days of field data gathering to guide the collection of spectral signatures of the maize, mixed, and weed classes. Spectral signatures were divided into training (70%) and validation (30%) data in a Random Forest (RF) model with S-2 spectral bands and vegetation indices as predictor variables. Spectral signatures were firstly tested for spectral separability between classes using ANOVA. The results of spectral analysis showed that the weed class had higher interclass variability from the maize and mixed class particularly in the red-edge and NIR regions of Sentinel-2. The classification matrix consistently showed that weeds were detected with high user and producers’ accuracy of 95%. These results indicate the utility of the enhanced spectral configuration of Sentinel-2 data in the early detection of weeds in maize farms.

Semimetallic Bismuthene with Edge-Rich Dangling Bonds: Broad-Spectrum-Driven and Edge-Confined Electron Enhancement Boosting CO2 Hydrogenation Reduction.

Broad-spectrum-driven high-performance artificial photosynthesis is quite challenging. Herein, atomically ultrathin bismuthene with semimetallic properties is designed and demonstrated for broad-spectrum (ultraviolet-visible-near infrared light) (UV-vis-NIR)-driven photocatalytic CO2 hydrogenation. The trap states in the bandgap produced by edge dangling bonds prolong the lifetime of the photogenerated electrons from 90ps in bulk Bi to 1650ps in bismuthine, and excited-state electrons are enriched at the edge of bismuthine. The edge dangling bonds of bismuthene as the active sites for adsorption/activation of CO2 increase the hybridization ability of the Bi 6p orbital and O 2p orbital to significantly reduce the catalytic reaction energy barrier and promote the formation of C─H bonds until the generation of CH4. Under λ≥400nm and λ≥550nm irradiation, the utilization ratios of photogenerated electron reduction CO2 hydrogenation to CO and CH4 for bismuthene are 58.24 and 300.50 times higher than those of bulk Bi, respectively. Moreover, bismuthene can extend the CO2 hydrogenation reaction to the near-infrared region (λ≥700nm). This pioneering work employs the single semimetal element as an artificial photosynthetic catalyst to produce a broad spectral response.

Heat action spectrum of Rhodamine B through two-photon absorption in near-infrared region studied by optical-probing photoacoustic spectroscopy

The heat action spectrum of Rhodamine B by two-photon absorption has been measured by a new system of optical-probing photoacoustic spectroscopy (OPPAS) coupled with a nanosecond near-infrared OPO laser. The highly resolved spectrum was obtained in the wide spectral range from 680 nm to 900 nm. The two-photon absorption cross-section of Rhodamine B was successfully determined by comparing the signal intensity of Rhodamine B with that of the reference. The OPPAS system was able to measure a well-resolved two-photon absorption spectrum of both fluorescent and non-fluorescent molecules in the wider spectral range from visible to near-infrared region.

Non-Fullerene Acceptors Assisted Target Therapy for Interface Treatment Enable High Performance Inverted Perovskite Solar Cells.

Targeted treatment of the interface between electron transport layers (ETL) and perovskite layers is highly desirable for achieving passivating effects and suppressing carrier nonradiative recombination, leading to high performance and long-term stability in perovskite solar cells (PSCs). In this study, a series of non-fullerene acceptors (NFAs, Y-H, Y-F, and Y-Cl) are introduced to optimize the properties of the perovskite/ETL interface. This optimization involves passivating Pb2+ defects, releasing stress, and modulating carrier dynamics through interactions with the perovskite. Remarkably, after modifying with NFAs, the absorption range of perovskite films into the near-infrared region is extended. As expected, Y-F, with the largest electrostatic potential, facilitates the strongest interaction between the perovskite and its functional groups. Consequently, champion power conversionefficiencies of 21.17%, 22.21%, 23.25%, and 22.31% are achieved for control, Y-H-, Y-F-, and Y-Cl-based FA0.88 Cs0.12 PbI2.64 Br0.36 (FACs) devices, respectively. This treatment also enhances the heat stability and air stability of the corresponding devices. Additionally, these modifier layers are applied to enhance the efficiency of Cs0.05 (FA0.95 MA0.05 )0.95 PbI2.64 Br0.36 (FAMA) devices. Notably, a champion PCE exceeding 24% is achieved in the Y-F-based FAMA device. Therefore, this study provides a facile and effective approach to target the interface, thereby improving the efficiency and stability of PSCs.

Prospects for Low-Resolution NDIR Sensors to Discern Ignition Properties of Fuels

Abstract The cetane number (CN) is an important fuel property to consider for compression ignition engines as it is a measure of a fuel's ignition delay. Derived cetane number (DCN) already varies significantly within jet fuels. With the expected increasing prevalence of alternative jet fuels, additional variability is expected. DCN is usually assigned to fuels using ASTM methods that use large equipment like the ignition quality tester (IQT), which consumes a lot of fuel and is cumbersome to operate. Over the last decade, there have been advances in the development of chemometric models, which use machine learning to correlate infrared spectra of fuels to fuel properties like DCN, density, and C/H ratio, among many others. These techniques have certain advantages over the ASTM methods, and previous studies performed on samples of diesel fuels have shown high accuracies in DCN prediction. However, this accuracy is generally a result of high resolution, making the equipment expensive, relatively large for handheld sensors, and power-hungry. On the other hand, nondispersive infrared (NDIR) sensors, despite having a low resolution, are attractive because they can be compact, inexpensive, and power efficient. These characteristics are important for handheld or onboard fuel sensors. However, one would anticipate a tradeoff between these advantages and accuracy. This study investigates this tradeoff and the feasibility of low-resolution NDIR sensors to discern fuel properties such as DCN by using Machine Learning models trained on real FTIR data, and DCNs obtained from IQT. DCN predictions were made for blends of ATJ/F-24, CN fuels, and neat Jet A1, A2, and JP 5, with an error limit of 10%. It was found that there seems to be sufficient variability in the near infrared (NIR) range to discern DCN with a feasible number of channels, but the channels have to be narrow (e.g., FWHMs as narrow as 60 nm). For the dataset in the study, the performance of linear models was better than the nonlinear model. Finally, NIR region beyond 1050 nm was found to be more important in DCN prediction, primarily the regions consisting of the first and second C-H overtones and the C-H combination band.