Absorption In Near-infrared Region Research Articles

Facile synthesis of Au nanorods in PVF2 non-aqueous solution with tailored absorption in near-infrared region

Facile synthesis of Au nanorods in PVF2 non-aqueous solution with tailored absorption in near-infrared region

Metamaterial ultra-broadband absorber in near-infrared region with decreasing thermal emission

This study is aimed to present an ultra-broadband metamaterial absorber for infrared detection and thermal emitter applications. Despite numerous studies on metamaterial absorbers, achieving ultra-broadband absorption remains a challenge. We introduce a dual-gold square array with transverse magnetic polarization and combine it with an anti-reflective (GaAs) layer and metal-insulator (gold-Al2O3) configurations. The absorber achieves over 90 % absorption between 0.63 μm and 2.90 μm, with average and effective absorptions at 94.60 % and 94.68 %, respectively. Through impedance matching theory, we validate the performance of the absorber, analyze electric field distributions to explain its mechanism, and assess manufacturing tolerance for practical application viability. Our findings reveal robust performance of the metamaterial absorber across a wide spectral range, including insensitivity to incidence angles, with absorption over 80 % in 20–60°, highlighting its potential in the infrared detection and the thermal emitter.

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.

High-Contrast Photoacoustic Imaging of Localized Cysteine in Orthotopic Breast Cancer Enabled by A Totally-Caged Methylene Blue Probe.

High-contrast photoacoustic sensing imaging (PASI) was greatly determined by optical absorption changes of the absorbers usually enabled by activatable probes via controllably converting the absorbed electromagnetic energy to ultrasound waves. However, most of current photoacoustic probes still suffer from limited imaging contrast towards specific species because of their small absorption spectral changes in the near infrared (NIR) region. Herein, we developed a methylene blue-based photoacoustic probe with its NIR optical absorption totally caged, which could afford dramatical "OFF-to-ON" absorption transition for high-contrast photoacoustic imaging towards the localized cysteine. The rationally designed methylene blue-based probe for cysteine (MB-Cys) would keep in off state with almost no absorption in NIR region, while upon activated by cysteine through cyclization reaction with acrylates, it would reconstruct the π-conjugation system to release the free methylene blue with strong absorption centered at 665 nm (>130-fold enhancement). The unique responsive behavior could enable the PASI for photoacoustic mapping the cysteine in orthotopic breast cancer in a high-contrast manner. Therefore, this work established an up-to-date strategy to originally eliminate the background photoacoustic signal for PASI to accurately monitor cysteine in vivo.

Annealing enhanced optical performances of nano-multilayered TiAlN/AlCrSiN-based solar selective absorber

Solar selective absorber is an important component to improve the solar thermal conversion efficiency of next-generation concentrated solar power with working temperature higher than 700 °C. However, the selective absorbers with thermal stability up to 700 °C are still lacking. Here, we designed a solar selective absorber based on nano-multilayered TiAlN/AlCrSiN films via thermal annealing, which could induce spinodal decomposition in TiAlN layer and form dual phase structure of Ti-rich and Al-rich cubic-TiAlN, to enhance the optical performances and thermal stability of the absorber. The obtained absorber after annealed at 900 °C exhibited a solar absorptance of 0.923 and a thermal emittance of 0.192, as well as small variation (0.935/0.232) after annealing at 700 °C for 100 h. However, after annealing the absorber at temperatures higher than 1000 °C, the N-loss induced the formation of metal CrSi2 phase and obviously decreased the absorption in near-infrared region. These results indicated the potential of the implement of spinodal decomposition to construct solar selective absorbers with high performances.

Improving solar modulation ability and luminous transmittance by embedding Mo nanoparticles between VO2/VO2/VO2 layers

For decades, the improvement of the solar modulation ability (ΔTsol) without weakening the luminous transmittance (Tlum) has always been a contradiction for VO2-based smart windows. In this research, VO2/Mo/VO2/Mo/VO2 composite films were fabricated by embedding Mo nanoparticles (NPs) into VO2/VO2/VO2 tri-layer films by pulsed laser deposition. SEM characterization results suggested that Mo NPs tended to nucleate at the junctions of grain boundaries of VO2, and thus affected the morphology of the top VO2 layer. The transmission spectra of the nanoporous sample (Mo180) showed an obvious phenomenon of localized surface plasmon resonance (LSPR). As a result, the ΔTsol and Tlum of Mo180 were significantly increased to 11.6% and 55.9%, respectively. In addition, the Finite-Different Time-Domain simulation proved that the LSPR comes from the top VO2 layer of the obtained composite films rather than the Mo NPs. The particle size and spacing of VO2 grains could particularly influence the electrical field distribution of the top layer and then regulate the absorption in near-infrared region. Our present work demonstrated that non-noble Mo NPs can be used as heterogeneous nucleation sites to control the surface morphology of VO2 films, thereby achieving the purpose of controlling the thermochromic properties.

A near-infrared photoacoustic probe for specific detection of fluoride ion in vivo

Fluoride is an essential trace element in the human body and plays an essential role in various physiological processes. However, fluoride ion detection in vivo remains challenging due to the lack of probes that can enter the organism and emit at the near infrared region (NIR). Herein, we developed a boron-dipyrromethene (BODIPY)-based NIR probe that takes advantage of the high resolution and deep penetration of photoacoustic imaging, which can produce high NIR absorption at 803 nm in the presence of fluoride ions, resulting in a strong photoacoustic signal in the NIR region. In addition, the probe exhibits high selectivity for fluoride ions. In view of these outstanding features, the probe was then successfully applied to fluoride ion imaging in living mice, proving that a probe is a promising tool for fluoride ion detection in vitro and in vivo.

Self-assembly of hydroxyapatite around Ti3C2 MXene/gold nanorods for efficient remotely triggered drug delivery

Ti3C2 MXene/gold nanorods (Ti3C2@AuNRs) nanosheets, a novel sandwich-like nanohybrids, have attracted extensive attention in the biomedical field due to its synergistically enhanced near-infrared (NIR) responsiveness and strong absorption in NIR region. In this study, hydroxyapatite (HAP) was self-assembled in situ around Ti3C2@AuNRs core and then combined with polydopamine (PDA) to prepare NIR-/pH- dual responsive Ti3C2@AuNRs/HAP/PDA nanocomposites. The obtained Ti3C2@AuNRs/HAP/PDA nanocomposites exhibited prominent photothermal conversion efficiency (38.6%) due to the synergistically enhanced NIR-responsive of Ti3C2@AuNRs. Ti3C2@AuNRs/HAP/PDA nanocomposites displayed excellent drug loading capacity (88.3%) for antitumor drug doxorubicin hydrochloride (DOX) because of the electrostatic interaction of negatively charged HAP nanorods and positively charged DOX, along with the distinct adhesiveness of PDA. In addition, the disintegration of HAP under acid medium and the strong NIR absorption of Ti3C2@AuNRs endowed the Ti3C2@AuNRs/HAP/PDA nanocomposites with pH-/NIR-dual responsive drug release behavior. In this paper, a feasible method is presented to prepare Ti3C2-based drug carriers with high drug loading capacity and remarkable multi-responsive drug release properties, which holds great promise in the field of remote controlled drug delivery and photothermal therapy.

Acidity-responsive cascade nanoreactor based on metal-nanozyme and glucose oxidase combination for starving and photothermal-enhanced chemodynamic antibacterial therapy

Persistent inflammation and bacterial infection are common during wound healing, and high blood sugar provides enough nutrients for bacterial growth to make wounds more prone to ulcers. Herein, glucose oxidase (GOx) is mineralized with calcium phosphate (CaP) circled Cu2O/Pt nanozyme to form a core–shell structural CaP-GOx-Cu2O/Pt (GOx-CaPCuPt) nanoreactor. The prepared biodegradable and acidity-responsive GOx-CaPCuPt nanoreactor can be used for near infrared imaging, photothermal enhanced cascade reaction and antibacterial therapy. Oxidation of glucose (Gs) by the GOx can significantly decrease Gs level for starvation therapy, and the generated H2O2 in this reaction is subsequently converted into highly active hydroxyl radicals (•OH) for chemodynamic therapy (CDT) and O2 for overcoming hypoxia via triple enzyme like activities (peroxidase, oxidase, and catalase) of Cu2O/Pt nanozyme. At the same time, the acidic microenvironment due to the generation of gluconic acid will in turn promote the degradation of the GOx-CuCaP nanoreactor and release of copper ions for enhanced angiogenesis. In addition, Cu2O/Pt nanoparticles have strong characteristic absorption in near-infrared region, which can induce a strong photothermal effect (PTT) under the irradiation of 808 nm laser. Under the guidance of near-infrared imaging, the multifunctional nanoreactor can achieve the combination of starvation therapy and PTT-enhanced CDT against Gram-negative and Gram-positive bacteria infectious diseases, which is demonstrated in the staphylococcus aureus infected diabetic rat models.

Carbon spheres with high photothermal conversion efficiency for photothermal therapy of tumor

Development of high-performance photothermal agent plays a decisive role in photothermal therapy of tumor. Herein, carbon spheres are rapidly synthesized by pyrolysis of pyrogallol-formaldehyde spheres at 400–1000 °C under nitrogen atmosphere. As-prepared carbon spheres exhibit strong absorption in near-infrared region and good photothermal effect. The results reveal that the photothermal conversion efficiency of carbon spheres has a tight association with carbon defects caused by pyrolysis. The carbon defects serve as the nonradiative recombination centers of the excited electrons to promote photothermal conversion efficiency. Strikingly, carbon spheres after calcination at 700 °C exhibit the photothermal conversion efficiency of 54.2% under 808 nm laser irradiation, which is superior to the reported carbon-based photothermal agents. The prepared carbon spheres have good cell biocompatibility and can ablate the tumor tissues in tumor-bearing mice through the conversion of near-infrared laser energy into thermal energy.

Near-infrared nonfullerene acceptors with halogenated terminated fused tris(thienothiophene) for efficient polymer solar cells

The fused-ring electron acceptors (FREAs) with A-D-A structures have experienced rapid development recent years. However, these FREAs still suffer the relative limited absorption in the near-infrared (NIR) region thus leading to low utilization of the solar light. Herein, two FREAs with strong absorption in NIR region, namely 6TIC-2Cl and 6TIC-2Br, were designed and synthesized by employing the fused tris(thienothiophene) (3TT) unit as the “D” along with 2-(5(6)-chloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (DCI-Cl) and 2-(5(6)-bromo-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (DCI-Br) as the end-groups, respectively. The strong electron-donating and molecular packing ability of 3TT and the enhanced electron-withdrawing ability of the halogenated terminal groups facilitated the intramolecular charge transfer thus bathochromic-shifting the absorption edges of 6TIC-2Cl and 6TIC-2Br to 940 nm and 934 nm, respectively. Consequently, the best-performing organic solar cells (OSCs) based on PBDB-T:6TIC-2Cl and PBDB-T:6TIC-2Br achieved the impressive short-circuit current density (JSC) of 23.83 mA cm−2 and 22.74 mA cm−2. In addition, the results showed that brominated terminal group was more beneficial to obtain a higher open-circuit voltage (VOC) and fill factor (FF) than the chlorinated end-group, which contributed to a decent PCE of 11.77%. This work revealed the impact of halogen atoms in the terminal group with 3TT units as core on the organic photovoltaic performance and provided guidance for designing SMAs with strong absorption in the visible-NIR region.

Plasmonically Modulated Gold Nanostructures for Photothermal Ablation of Bacteria.

With the wide utilization of antibiotics, antibiotic-resistant bacteria have been often developed more frequently to cause potential global catastrophic consequences. Emerging photothermal ablation has been attracting extensive research interest for quick/effective eradication of pathogenic bacteria from contaminated surroundings and infected body. In this field, anisotropic gold nanostructures with tunable size/morphologies have been demonstrated to exhibit their outstanding photothermal performance through strong plasmonic absorption of near-infrared (NIR) light, efficient light to heat conversion, and easy surface modification for targeting bacteria. To this end, this review first introduces thermal treatment of infectious diseases followed by photothermal therapy via heat generation on NIR-absorbing gold nanostructures. Then, the usual synthesis and spectral features of diversified gold nanostructures and composites are systematically overviewed with the emphasis on the importance of size, shape, and composition to achieve strong plasmonic absorption in NIR region. Further, the innovated photothermal applications of gold nanostructures are comprehensively demonstrated to combat against bacterial infections, and some constructive suggestions are also discussed to improve photothermal technologies for practical applications.

First theoretical framework of Z-shaped acceptor materials with fused-chrysene core for high performance organic solar cells.

Chrysene core containing fused ring acceptor materials have remarkable efficiency for high performance organic solar cells. Therefore, present study has been carried out with the aim to design chrysene based novel Z-shaped electron acceptor molecules (Z1-Z6) from famous Z-shaped photovoltaic material FCIC (R) for organic photovoltaic applications. End-capped engineering at two electron-accepting end groups 1,1-dicyanomethylene-3-indanone of FCIC is made with highly efficient end-capped acceptor moieties and impact of end-capped modifications on structure-property relationship, photovoltaic and electronic properties of newly designed molecules (Z1-Z6) has been studied in detail through DFT and TDDFT calculations. The efficiencies of the designed molecules are evaluated through energy gaps, exciton binding energy along with transition density matrix (TDM) analysis, reorganizational energy of electron and hole, absorption maxima and open circuit voltage of investigated molecules. The designed molecules exhibit red-shift and intense absorption in near-infrared region (683-749nm) of UV-Vis-NIR absorption spectrum with narrowing of HOMO-LUMO energy gap from 2.31eV in R to 1.95 in eV in Z5. Moreover, reduction in reorganization energy of electron from 0.0071 (R) to 0.0049 (Z5), and enhancement in open circuit voltage from 1.08V in R to 1.20V in Z5 are also observed. Twisted Z-shape of designed molecules prevents self-aggregation that facilitates miscibility of donor and acceptor. Low values of binding energy, excitation energy, and reorganizational energy (electron and hole) suggest that novel designed molecules offer high charge mobilities as compared to FCIC. Our findings indicate that these novel designed molecules can display better photovoltaic parameters and are suitable candidates if used in organic solar cells.

Morphology‐controlled Synthesis of Molybdenum Oxide with Tunable Plasmon Absorption for Phothermal Therapy of Cancer

AbstractSemiconductor nanocrystals showing surface plasmonic absorption features can be used as prospective substitutes for noble metallic nanoparticles. Herein, a creative one‐pot hydrothermal route without template is used to synthesize plasmonic oxygen deficiency molybdenum oxide (MoO3‐x) nanoparticles. The morphologies of as‐prepared MoO3‐x nanomaterials arranged from amorphous to crystalline with the reaction temperature varied from 160 °C, 180 °C to 200 °C, namely MoO3‐x quantum dots (QDs), MoO3‐x nanosheets, and MoO2 nanospheres. Simultaneously, in the near‐infrared region (NIR), MoO3‐x nanomaterials exhibit gradually enhanced localized surface plasmon resonance (LSPR) absorption, of which MoO2 nanospheres exhibit intense NIR absorption with a photothermal conversion efficiency up to 72.5% under 808 nm NIR laser irradiation. Moreover, the toxicity and cancer therapy efficacy of MoO2 nanospheres have been systematically assessed in vitro and in vivo, respectively. The results revealed that MoO2 nanospheres exhibit low toxicity and high therapeutic efficiency, making it an promising and effective photothermal agent in photothermal therapy

A nonfullerene acceptor incorporating a dithienopyran fused backbone for organic solar cells with efficiency over 14%

Abstract An acceptor-donor-acceptor (A-D-A) type small molecule acceptor ITOT-4Cl incorporating a dithienopyran (DTP) fused backbone, has been designed and synthesized. With the strong electron-donating capability of the backbone D unit, ITOT-4Cl shows a narrow band gap of 1.28 eV, and has an efficient absorption in near-infrared region up to 968 nm. The photovoltaic devices based on PBDB-T:ITOT-4Cl give a power conversion efficiency (PCE) of 12.50%, with a high short circuit current density (Jsc) of 22.89 mA cm−2. With F–Br as the third component, the ternary organic solar cells device shows an enhanced PCE of 14.29% with an improved Jsc of 24.40 mA cm−2, which is among the best results for oxygen heterocycle fused nonfullerene acceptor based devices.

Sensing and switching capabilities of a tunable GST-based perfect absorber in near-infrared region

In this paper a GST-based perfect absorber is investigated for sensing applications. The simulation results show the high sensitivity and figure of merit of 900 nm per refractive index unit (RIU) and 15 RIU−1, respectively. The sensing parameters are also studied for different biomedical applications such as detection of glucose in water, malaria infection, bacillus bacteria, and cancer cells. The phase change material GST makes the structure tunable and switchable by changing the phase through different annealing temperatures. By changing temperature, the optical characteristics of GST are altered and so the perfect absorption can be tuned at different near-infrared wavelengths. Moreover, the sweep between the amorphous and crystalline states of GST results in switching capability with the high extinction ratio of 13.97 dB at λ = 1724 nm. Therefore, the perfect tunable absorber supports our new idea of multi-application plasmonic devices with two capabilities of sensing and switching, simultaneously. Also, the E-field distributions and analytical method of equivalent circuit model are utilized to verify the simulation results and demonstrate a better insight of the proposed structure performance. The polarization independency of the proposed structure, tunability, good sensing and switching performances are some other benefits of our proposed structure, which can pave the way for development of new investigations about the phase change material applications in plasmonic studies.

Near-infrared absorption enhancement for perovskite solar cells via the rear grating design

Optical management and design is one of the most effective methods to unlock the full potential of photocurrent density and power conversion efficiency for perovskite solar cells (PSCs). However, the common-used optical designs are still limited by the near-infrared response. Here, we proposed an effective optical structure in PSCs by texturing the rear-side perovskite layer with a rectangular grating to promote the optical response in the near-infrared region. Through the comprehensive numerical simulations, the new design under the optimized structural configuration shows an improved photocurrent density, i.e., from 22.75 (flat structure) to 23.72 mA/cm2. We confirm that the optical absorption enhancement occurs at the near-infrared region by the wavelength-dependent absorption and reflection spectra. Besides, the light-trapping mechanism was clarified by the comprehensive analysis of the electric field distributions. Moreover, PSCs having the rear-grating design demonstrate the superior optical performance compared to that of flat design in the varied incident angles. Our simulation results displayed in this study provide an easy scheme to promote the optical absorption in near-infrared region.

Iridium(III) Complex-Derived Polymeric Micelles with Low Dark Toxicity and Strong NIR Excitation for Phototherapy and Chemotherapy.

Iridium(III) complexes are potent candidates for photodynamic therapy. However, their clinical usage is impeded by their poor water solubility, high dark toxicity, and negligible absorption in near-infrared region (NIR region). Here, it is proposed to solve these challenges by developing an iridium(III) complexe-based polymeric micelle system. This system is self-assembled using an iridium(III) complex-containing amphiphilic block polymer. The upconversion nanoparticles are included in the polymeric micelles to permit NIR excitation. Compared with the nonformulated iridium(III) complexes, under NIR stimulation, this polymeric micelle system exhibits higher 1 O2 generation efficiency, negligible dark toxicity, excellent tumor-targeting ability, and synergistic phototherapy-chemotherapy effect both in vitro and in vivo.

A novel NIR-controlled NO release of sodium nitroprusside-doped Prussian blue nanoparticle for synergistic tumor treatment

Nitric oxide (NO) has shown positive effects in tumor treatment. However, controlling NO release in specific targets is still a crucial challenge for antitumor therapy. Considering that sodium nitroprusside (SNP) and potassium ferricyanide have similar chemical structures, a near infrared (NIR) laser-controlled NO release nanoplatform has been fabricated by allowing SNP to participate in mesoporous Prussian blue (m-PB) nanoparticle formation. The resulting SNP-doped m-PB (m-PB-NO) exhibited a good NIR-controlled NO release behavior, and the amount of NO released can be controlled by adjusting the laser intensity and irradiation time. Given that m-PB-NO still has strong absorption in NIR region, it exhibited an excellent photothermal effect in vitro and in vivo. After carrying antitumor drug, docetaxel (DTX)-loaded m-PB-NO (DTX@m-PB-NO) can simultaneously achieve NIR-controlled NO release, good photothermotherapy, and chemotherapy. The combination therapy of DTX@m-PB-NO showed a significant synergistic effect compared with each monotherapy and can significantly improve the therapeutic effect. Combination therapy also significantly inhibited the lung metastasis of 4T1 breast cancer cells in tumor-bearing mice by ablating primary tumors.

Self-Assembled Porphyrin-Based Nanoparticles with Enhanced Near-Infrared Absorbance for Fluorescence Imaging and Cancer Photodynamic Therapy.

Two novel meso-A2B2-porphyrins (P1 and P2) with symmetrical phenylethynyl groups were synthesized by introducing amphiphilic triethylene glycol moieties onto the parent structure, which improved the near-infrared (NIR) absorbance and resulted in efficient singlet oxygen (1O2) generation. Through solvent-exchange based self-assembly approach, the corresponding hydrophilic nanoparticles (NPs) were fabricated. Thereby, as-prepared NP1 and NP2 presented obvious red-shifted absorbance in NIR region with homogeneous size, superb biocompatibility, higher 1O2 generation, and good phototoxicity as well as low dark cytotoxicity. Furthermore, cellular uptake behavior of the NPs was evaluated by confocal microscopy, which demonstrated that the NPs could easily go through the cell membrane and distribute in cytoplasm with desired fluorescence imaging performance. All results suggest the potential application of the two porphyrin-based NPs in fluorescence imaging guided cancer photodynamic therapy.