Controllable Generation of Nitric Oxide by Near‐Infrared‐Sensitized Upconversion Nanoparticles for Tumor Therapy

NaYbF₄:Tm@NaYF₄:Yb/Er upconversion nanoparticles are synthesized and then integrated with light‐sensitive nitric oxide (NO) donors (Roussin's black salt) to construct a novel near‐infrared (NIR)‐triggered on‐demand NO delivery platform. This nanocompound can absorb 980 nm NIR photons, convert them into higher energy photons and then transfer the energy to the NO donors, resulting in an efficient release of NO. By manipulating the output power of the 980‐nm NIR light, NO‐concentration‐dependent biological effects for cancer therapy can be fine‐tuned, which is investigated and confirmed in vitro. High concentrations of NO can directly kill cancer cells and low concentrations of NO can act as a potent P‐glycoprotein (P‐gp) modulator to overcome multi‐drug resistance (MDR) if combined with chemotherapy.     

Near‐Infrared Electric Power Generation Through Sub‐Energy‐Gap Absorption in an Organic–Inorganic Composite

Exploitation of energy from the near‐infrared (NIR) region is one strategic approach for enhancing the performance of organic photovoltaic devices (OPVs). While effort has been mostly put toward developing materials with narrow energy gaps, here, a simple approach for harvesting NIR photons with wide‐energy‐gap materials by making use of their interactive charge‐transfer complex (CTC) is shown. It is shown using photoemission studies that the interface between molybdenum (VI) oxide and 5,6,11,12‐tetraphenylnaphthacene (MoO₃/rubrene) possesses an abrupt discontinuity in the vacuum level (VL), resulting in significantly overlapped electron wavefunctions and CTC formation. The CTC induces an intermediate state within the original energy gap of rubrene with energy of ≈1.3 eV, suggesting the feasibility of a charge transfer (CT) exciton generated upon NIR excitation. This is confirmed by generation of electric power OPVs with an active layer of MoO₃:rubrene composite under excitation with a NIR light source.     

Solution‐Processable Perovskite Solar Cells toward Commercialization: Progress and Challenges

In the last few years, organometal halide perovskites (OHPs) have emerged as a promising candidate for photovoltaic (PV) applications. A certified efficiency as high as 23.7% has been achieved, which is comparable with most of the well‐established PV technologies. Their good solubility due to the ionic nature enables versatile low‐temperature solution processes, including blade coating, slot‐die coating, etc., most of which are scalable and compatible with roll‐to‐roll large‐scale manufacturing processes. The low cost, high efficiency, and facile processable features make perovskite solar cells (PSCs) a very competitive PV technology. Despite the great progress, long‐term durability concerns, toxicity issues of both materials and manufacturing process, and lack of robust high‐throughput production technology for fabricating efficient large‐area modules are major obstacles toward commercialization. In this review, the recent progress of commercially available process of PSCs is surveyed, the underlying determinants for upscaling high‐quality PSCs from hydrodynamic characteristics and crystallization thermodynamic mechanism are identified, the influence of external stress factors on stability of PSCs and intrinsic instability mechanism in OHPs themselves is revealed, and the environmental impact and sustainable development of PSC technology are analyzed. Strategies and opportunities for large‐scale production of PSCs are suggested to promote the development of PSCs toward commercialization.     

Highly Sensitive Low‐Bandgap Perovskite Photodetectors with Response from Ultraviolet to the Near‐Infrared Region

It is a great challenge to obtain broadband response perovskite photodetectors (PPDs) due to the relatively large bandgaps of the most used methylammonium lead halide perovskites. The response range of the reported PPDs is limited in the ultraviolet–visible range. Here, highly sensitive PPDs are successfully fabricated with low bandgap (≈1.25 eV) (FASnI₃)_0.6(MAPbI₃)_0.4 perovskite as active layers, exhibiting a broadband response from 300 to 1000 nm. The performance of the PPDs can be optimized by adjusting the thicknesses of the perovskite and C₆₀ layers. The optimized PPDs with 1000 nm thick perovskite layer and 70 nm thick C₆₀ layer exhibit an almost flat external quantum efficiency (EQE) spectrum from 350 to 900 nm with EQE larger than 65% under ?0.2 V bias. Meanwhile, the optimized PPDs also exhibit suppressed dark current of 3.9 nA, high responsivity (R ) of over 0.4 A W^?1, high specific detectivity (D* ) of over 10¹² Jones in the near‐infrared region under ?0.2 V. Such highly sensitive broadband response PPDs, which can work well as self‐powered conditions, offer great potential applications in multicolor light detection.     

2D Perovskite Seeding Layer for Efficient Air‐Processable and Stable Planar Perovskite Solar Cells

Despite the record power conversion efficiencies, inverted perovskite solar cells (PSCs) are still looking to overcome the challenge of moisture instability. This is mitigated by introducing 2D perovskite at the base of a 3D perovskite via coating of ethylenediamine bications on top of the hole transport layer of p–i–n planar configured devices. The cations induce thin 2D perovskite growth beneath the 3D perovskite to create a 2D/3D hybrid active layer. This 2D layer in turn acts as a template for the growth of relatively large grains compared to that of pure 3D perovskite films. This stems from the merging of grain boundaries. The hydrophobicity of the 2D/3D perovskite film consequently improves, as evidenced by a large contact angle of 93.1°, compared to 68.9° for the 3D perovskite film. Because there are fewer defects sourced from grain boundaries, the air‐processed 2D/3D perovskite devices yield a high power conversion efficiency of 15.02%, compared to 13.10% from 3D perovskite devices. When stored in moderately humid environment of 55% relative humidity, the 2D/3D devices exhibit longer stabilities, with 75% of their power conversion efficiencies maintained after 150 h, compared to a total loss in efficiency for 3D device in the same time frame.     

Accurate Control of Core–Shell Upconversion Nanoparticles through Anisotropic Strain Engineering

The effect of anisotropic interfacial strain on epitaxial growth and optical emission of sodium rare‐earth fluoride core–shell nanoparticles is investigated. A variety of sodium rare‐earth fluoride shells are grown on hexagonal‐phase NaYF₄:Yb/Er core for providing anisotropic tuning of interfacial strains. Using high‐resolution transmission electron microscopy and X‐ray diffraction characterizations, the correlations between the epitaxial habits and the interfacial strains are quantitatively addressed. Furthermore, the growth affinity is tuned by controlling precursor concentration in conjunction with Ca²⁺ doping, which results in accurate regulation of the anisotropic growth. The lattice strain resulting from mismatched epitaxy is found to enhance luminescence response of the nanoparticles to temperature change.     

Neuroendocrine Tumor‐Targeted Upconversion Nanoparticle‐Based Micelles for Simultaneous NIR‐Controlled Combination Chemotherapy and Photodynamic Therapy,and Fluorescence Imaging

Although neuroendocrine tumors (NETs) are slow growing, they are frequently metastatic at the time of discovery and no longer amenable to curative surgery, emphasizing the need for the development of other treatments. In this study, multifunctional upconversion nanoparticle (UCNP)‐based theranostic micelles are developed for NET‐targeted and near‐infrared (NIR)‐controlled combination chemotherapy and photodynamic therapy (PDT), and bioimaging. The theranostic micelle is formed by individual UCNP functionalized with light‐sensitive amphiphilic block copolymers poly(4,5‐dimethoxy‐2‐nitrobenzyl methacrylate)‐polyethylene glycol (PNBMA‐PEG) and Rose Bengal (RB) photosensitizers. A hydrophobic anticancer drug, AB3, is loaded into the micelles. The NIR‐activated UCNPs emit multiple luminescence bands, including UV, 540 nm, and 650 nm. The UV peaks overlap with the absorption peak of photocleavable hydrophobic PNBMA segments, triggering a rapid drug release due to the NIR‐induced hydrophobic‐to‐hydrophilic transition of the micelle core and thus enabling NIR‐controlled chemotherapy. RB molecules are activated via luminescence resonance energy transfer to generate ¹O₂ for NIR‐induced PDT. Meanwhile, the 650 nm emission allows for efficient fluorescence imaging. KE108, a true pansomatostatin nonapeptide, as an NET‐targeting ligand, drastically increases the tumoral uptake of the micelles. Intravenously injected AB3‐loaded UCNP‐based micelles conjugated with RB and KE108—enabling NET‐targeted combination chemotherapy and PDT—induce the best antitumor efficacy.     

Removing the Obstacle of Dye‐Sensitized Upconversion Luminescence in Aqueous Phase to Achieve High‐Contrast Deep Imaging In Vivo

Although upconversion nanoparticles (UCNPs) have drawn increasing attention for their unique photophysical characteristics, they suffer from a bottleneck of low luminescence efficiency due to the poor absorption coefficient of Ln³⁺. Dye sensitization has provided thousands‐fold enhancement of upconversion luminescence (UCL) in organic solvents because of the remarkably improved light absorption ability, but the sensitization of UCL in aqueous phase is only less than 20 folds by far, with unknown restrictive factors. Herein, the aggregation‐caused quenching (ACQ) of dyes is revealed as the most important reason limiting dye sensitization in aqueous phase, and the problem is circumvented through delicately modulating the physical properties of dyes and their assembly manner with UCNPs. By further alleviating energy back transfer (EBT) from Ln³⁺ to dyes, more than 600‐fold enhancement of UCL is achieved in aqueous phase. The as‐obtained dyes modified UCNPs show good biocompatibility and high signal contrast when applied for deep in vivo imaging.     

Intraband Cooling in All‐Inorganic and Hybrid Organic–Inorganic Perovskite Nanocrystals

Intraband relaxation in all‐inorganic cesium lead tribromide (CsPbBr₃) and hybrid organic–inorganic formamidinium lead tribromide (FAPbBr₃) nanocrystals is experimentally investigated for a range of particle sizes, excitation energies, sample temperatures, and excitation fluences. Hot carriers in CsPbBr₃ nanocrystals consistently exhibit slower cooling than FAPbBr₃ nanocrystals in the single electron–hole pair per nanocrystal regime. In both compositions, long‐lived hot carriers (>3 ps) are only observed at excitation densities corresponding to production of multiple electron–hole pairs per nanocrystal—and concomitant Auger recombination. These presented results are distinct from previous reports in bulk hybrid perovskite materials that convey persistent hot carriers at low excitation fluences. Time‐resolved photoluminescence confirms the rapid cooling of carriers in the low‐fluence (single electron–hole pair per nanocrystal) regime. Intraband relaxation processes, as a function of excitation energy, size, and temperature are broadly consistent with other nanocrystalline semiconductor materials.     

A Visible‐ and NIR‐Light Responsive Photothermal Therapy Agent by Chirality‐Dependent MoO3−x Nanoparticles

Chirality‐based semiconducting nanocrystals, as an emerging area, are envisioned to have great potential in chiral sensing, biomedicine, and chiroptical devices. Herein, chiral substoichiometric molybdenum oxide (l /d ‐Cys‐MoO_3?x) nanoparticles are synthesized via step‐by‐step reduction treatment with chiral cysteine molecules. The obtained nanoparticles are used as visible‐ and near‐infrared‐light dual responsive photothermal therapy agent for tumor cell ablation. Notably, the chiral nanoparticles show chiral selectivity for incident light, i.e., when irradiated by left‐circularly polarized light, l ‐Cys‐MoO_3?x is the most sensitive agent giving the highest mortality for HeLa cell ablation in vitro, and vice versa for right‐circularly polarized light with d ‐Cys‐MoO_3?x. In comparison to traditional photothermal therapy with near‐field light source, the investigations with chiral visible light at 532 nm indicate the possibility of chiral Cys‐MoO_3?x nanoparticles for visible light‐based phototherapy via metal–ligand charge transfer chirality, which provides insights for new methods in nanotechnology supported photothermal treatments.     

Simultaneously Excited Downshifting/Upconversion Luminescence from Lanthanide‐Doped Core/Shell Fluoride Nanoparticles for Multimode Anticounterfeiting

This work presents a novel anticounterfeiting strategy based on a material changing its emission color in response to a change in the excitation sources—where a single ultraviolet (UV) or near‐infrared (NIR) light source are employed or simultaneously using two excitation sources (xenon lamp and NIR laser). Following this approach, various combinations of lanthanide (Ln³⁺)‐doped LiLuF₄/LiYF₄ core/shell nanoparticles are prepared, providing a promising route to design flexible nanomaterials, as well as already a small library of luminescent materials, which change color when varying the excitation source (UV, NIR or both UV and NIR). Aside from excitation source‐dependent color change, these materials additionally show excitation‐source power‐dependent color change. This work exploits the possibility of developing a new class of multimode anticounterfeit nanomaterials, with excellent performance, which would be almost impossible to mimic or replicate, providing a very high level of security.     

Intraperitoneal Administration of Biointerface‐Camouflaged Upconversion Nanoparticles for Contrast Enhanced Imaging of Pancreatic Cancer

Pancreatic cancer has one of the highest fatality rates of all diseases, but poor drug availability after intravenous (IV) administration has hindered the diagnosis and treatment of patients. Herein, the authors report a novel strategy, combining intraperitoneal administration and phosphatidylcholine‐camouflaged NaLuF₄:Yb,Tm/NaLuF₄/NaDyF₄ upconversion nanoparticles (UCNP@PC) to gain the enhanced dual‐modal imaging (upconversion luminescence/magnetic resonance imaging) of orthotopic pancreatic cancer. Remarkably, the authors observe a 16‐fold improvement in the efficacy of utilization promoted intraperitoneally administered UCNP@PC in monitoring orthotopic pancreatic cancer compared with IV approach. Benefiting from modification with phosphatidylcholine, a major component of cell membranes, the optimized nanostructures show excellent biocompatibility and are rapidly excreted via the bile pathway after their intraperitoneal administration. The integration of the advanced design of UCNP@PC and the optimal drug administration route also give a general strategy for the advanced diagnosis and treatment of a series of intraperitoneal cancers.     

A Hybrid Material Approach Toward Solution‐Processable Dielectrics Exhibiting Enhanced Breakdown Strength and High Energy Density

The ever‐increasing demand for compact electronics and electrical power systems cannot be met with conventional dielectric materials with limited energy densities. Numerous efforts have been made to improve the energy densities of dielectrics by incorporating ceramic additives into polymer matrix. In spite of increased permittivities, thus‐fabricated polymer nanocomposites typically suffer from significantly decreased breakdown strengths, which preclude a substantial gain in energy density. Herein, organic–inorganic hybrids as a new class of dielectric materials are described, which are prepared from the covalent incorporation of tantalum species into ferroelectric polymers via in situ sol‐gel condensation. The solution‐processed hybrid with the optimal composition exhibits a Weibull breakdown strength of 505 MV m^?1 and a discharged energy density of 18 J cm^?3, which are more than 40% and 180%, respectively, greater than the pristine ferroelectric polymer. The superior performance is mainly ascribed to the deep traps created in the hybrids at the molecular level, which results in reduced electric conduction and lower remnant polarization. Simultaneously, the formation of the cross‐linked networks enhances the mechanical strengths of the hybrid films and thus hinders the occurrence of the electromechanical breakdown. This work opens up new opportunities to solution‐processed organic materials with high energy densities for capacitive electrical energy storage.     

Near‐Infrared and Short‐Wavelength Infrared Photodiodes Based on Dye–Perovskite Composites

Organohalide perovskites have emerged as promising light‐sensing materials because of their superior optoelectronic properties and low‐cost processing methods. Recently, perovskite‐based photodetectors have successfully been demonstrated as both broadband and narrowband varieties. However, the photodetection bandwidth in perovskite‐based photodetectors has so far been limited to the near‐infrared regime owing to the relatively wide band gap of hybrid organohalide perovskites. In particular, short‐wavelength infrared photodiodes operating beyond 1 µm have not yet been realized with organohalide perovskites. In this study, narrow band gap organic dyes are combined with hybrid perovskites to form composite films as active photoresponsive layers. Tuning the dye loading allows for optimization of the spectral response characteristics and excellent charge‐carrier mobilities near 11 cm² V^?1 s^?1, suggesting that these composites combine the light‐absorbing properties or IR dyes with the outstanding charge‐extraction characteristics of the perovskite. This study demonstrates the first perovskite photodiodes with deep near‐infrared and short‐wavelength infrared response that extends as far as 1.6 µm. All devices are solution‐processed and exhibit relatively high responsivity, low dark current, and fast response at room temperature, making this approach highly attractive for next‐generation light‐detection techniques.     

Yb3+/Ho3+共掺碲酸盐玻璃的能量传递和上转换发光

制备了75TeO2-20ZnO-(3-x)La2O3-2Yb2O3-xHo2O3(TZLH x,x=0,0.2,0.4,1,2 mol %),75TeO2-20ZnO-(4.6)La2O3-0.4Ho2O3系列玻璃样品,研究了975nm泵浦下,在Yb3 离子浓度确定的情况下,Ho3 离子浓度的变化对Ho3 上转换发光的影响并分析了上转换发光机制.结果表明,随着Ho3 离子含量的增大,549nm绿光强度先增大而后减小.在TZLH-0.4玻璃中,即含有0.4mol%Ho2O3时,绿光强度达到最大值.而当Ho2O3含量超过0.4mol%时,绿光强度明显降低.基于Yb3 和Ho3 的能级图及上转换机制建立了速率方程,通过数值求解速率方程拟合实验测量寿命曲线,得出了Yb3 与Ho3 之间的能量转移系数CDi(i=2,3,4).     

Self‐Crystallized Multifunctional 2D Perovskite for Efficient and Stable Perovskite Solar Cells

Recently, perovskite solar cells (PSC) with high power‐conversion efficiency (PCE) and long‐term stability have been achieved by employing 2D perovskite layers on 3D perovskite light absorbers. However, in‐depth studies on the material and the interface between the two perovskite layers are still required to understand the role of the 2D perovskite in PSCs. Self‐crystallization of 2D perovskite is successfully induced by deposition of benzyl ammonium iodide (BnAI) on top of a 3D perovskite light absorber. The self‐crystallized 2D perovskite can perform a multifunctional role in facilitating hole transfer, owing to its random crystalline orientation and passivating traps in the 3D perovskite. The use of the multifunctional 2D perovskite (M2P) leads to improvement in PCE and long‐term stability of PSCs both with and without organic hole transporting material (HTM), 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) compared to the devices without the M2P.     

Plasmonic Dual‐Enhancement and Precise Color Tuning of Gold Nanorod@SiO2 Coupled Core–Shell–Shell Upconversion Nanocrystals

The last decade has witnessed the remarkable research progress of lanthanide‐doped upconversion nanocrystals (UCNCs) at the forefront of promising applications. However, the future development and application of UCNCs are constrained greatly by their underlying shortcomings such as significant nonradiative processes, low quantum efficiency, and single emission colors. Here a hybrid plasmonic upconversion nanostructure consisting of a GNR@SiO₂ coupled with NaGdF₄:Yb³⁺,Nd³⁺@NaGdF₄:Yb³⁺,Er³⁺@NaGdF₄ core–shell–shell UCNCs is rationally designed and fabricated, which exhibits strongly enhanced UC fluorescence (up to 20 folds) and flexibly tunable UC colors. The experimental findings show that controlling the SiO₂ spacer thickness enables readily manipulating the intensity ratio of the Er³⁺ red, green, and blue emissions, thereby allowing us to achieve the emission color tuning from pale yellow to green upon excitation at 808 nm. Electrodynamic simulations reveal that the tunable UC colors are due to the interplay of plasmon‐mediated simultaneous excitation and emission enhancements in the Er³⁺ green emission yet only excitation enhancement in the blue and red emissions. The results not only provide an upfront experimental design for constructing hybrid plasmonic UC nanostructures with high efficiency and color tunability, but also deepen the understanding of the interaction mechanism between the Er³⁺ emissions and plasmon resonances in such complex hybrid nanostructure.     

Single Ho3+‐Doped Upconversion Nanoparticles for High‐Performance T2‐Weighted Brain Tumor Diagnosis and MR/UCL/CT Multimodal Imaging

Multimodal bio‐imaging has attracted great attention for early and accurate diagnosis of tumors, which, however, suffers from the intractable issues such as complicated multi‐step syntheses for composite nanostructures and interferences among different modalities like fluorescence quenching by MRI contrast agents (e.g., magnetic iron oxide NPs). Herein, the first example of T₂‐weighted MR imaging of Ho³⁺‐doped upconversion nanoparticles (UCNPs) is presented, which, very attractively, could also be simultaneously used for upconversion luminesence (UCL) and CT imaging, thus enabling high performance multi‐modal MRI/UCL/CT imagings in single UCNPs. The new finding of T₂‐MRI contrast enhancement by integrated sensitizer (Yb³⁺) and activator (Ho³⁺) in UCNPs favors accurate MR diagnosis of brain tumor and provides a new strategy for acquiring T₂‐MRI/optical imaging without fluorescence quenching. Unlike other multi‐phased composite nanostructures for multimodality imaging, this Ho³⁺‐doped UCNPs are featured with simplicity of synthesis and highly efficient multimodal MRI/UCL/CT imaging without fluorescence quenching, thus simplify nanostructure and probe preparation and enable win–win multimodality imaging.     

Controlled Fabrication of PbS Quantum‐Dot/Carbon‐Nanotube Nanoarchitecture and its Significant Contribution to Near‐Infrared Photon‐to‐Current Conversion

A solution‐processed nanoarchitecture based on PbS quantum dots (QDs) and multi‐walled carbon nanotubes (MWCNTs) is synthesized by simply mixing the pre‐synthesized high‐quality PbS QDs and oleylamine (OLA) pre‐functionalized MWCNTs. Pre‐functionalization of MWCNTs with OLA is crucial for the attachment of PbS QDs and the coverage of QDs on the surface of MWCNTs can be tuned by varying the ratio of PbS QDs to MWCNTs. The apparent photoluminescence (steady‐state emission and fluorescence lifetime) “quenching” effect indicates efficient charge transfer from photo‐excited PbS QDs to MWCNTs. The as‐synthesized PbS‐QD/MWCNT nanoarchitecture is further incorporated into a hole‐conducting polymer poly(3‐hexylthiophene)‐(P3HT), forming the P3HT:PbS‐QD/MWCNT nanohybrid, in which the PbS QDs act as a light harvester for absorbing irradiation over a wide wavelength range of the solar spectrum up to near infrared (NIR, ≈1430 nm) range; whereas, the one‐dimensional MWCNTs and P3HT are used to collect and transport photoexcited electrons and holes to the cathode and anode, respectively. Even without performing the often required “ligand exchange” to remove the long‐chained OLA ligands, the built nanohybrid photovoltaic (PV) device exhibits a largely enhanced power conversion efficiency (PCE) of 3.03% as compared to 2.57% for the standard bulk hetero‐junction PV cell made with P3HT and [6,6]‐Phenyl‐C₆₁‐Butyric Acid Methyl Ester (PCBM) mixtures. The improved performance of P3HT:PbS‐QD/MWCNT nanohybrid PV device is attributed to the significantly extended absorption up to NIR by PbS QDs as well as the effectively enhanced charge separation and transportation due to the integrated MWCNTs and P3HT. Our research results suggest that properly integrating QDs, MWCNTs, and polymers into nanohybrid structures is a promising approach for the development of highly efficient PV devices.