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With the promulgation of industry guidelines, near infrared spectroscopy (NIRS) monitoring the uniformity of solid oral preparations has become one of the most reported studies. The purpose of the present study is to develop a near infrared (NIR) method for the in-line assessment of the active pharmaceutical ingredient (API) content in the fluidized bed mixing process, as well as to introduce a portable NIR sensor to monitor the fluidized bed production visually. A portable NIR sensor was used to monitor the content of the API in the fluidized bed mixing process. An experimental fluidized bed was performed and the corresponding NIR spectra were collected in-line. The spectrum selection method of cosine distance for in-line spectra was performed, and four wavelength optimization methods were compared to improve the accuracy of the model. Throughout the mixing process, the content uniformity of the API was a critical quality attribute (CQA). The partial least squares regression (PLSR) quantitative model of API content was established. The results showed that the cosine distance combined with the multi-variable selection methods (CC, VIP, RATC, and UVE) could obtain more useful information than the single method. The root mean square error of cross validation (RMSECV) and root mean square error of prediction (RMSEP) values of the optimal PLSR model were 1.8588% and 1.5296%, respectively. Based on the results obtained, this study could be used as a reference for the pilot of in-line monitoring of miniature NIR sensors and the connection of key process parameters to realize intelligent production of solid preparations.

CsPbBr3-(SH)polyHIPE composite was produced by adhering CsPbBr3 nanocrystals to a (SH)-polyHIPE substrate. This well-designed composite has an extremely high sensitivity to copper ions in organic solvents.

The application of process analysis and control is essential to enhance process understanding and ensure output material quality. The present study focuses on the stability of the feedback control system for a fluidized bed granulation process. Two strategies of dynamic moisture control (DMC) and static moisture control (SMC) were established based on the in-line moisture value obtained from the near-infrared sensor and control algorithm. The performance of these strategies on quality consistency control was examined using process moisture similarity analysis and principal component analysis. The stable moisture control performance and low batch-to-batch variability indicated that the DMC method was significantly better than other granulation methods. In addition, the investigation of robustness further showed that the implemented DMC method was able to produce predetermined target moisture values by varying process parameters. This study provides an advanced and simple control method for fluidized bed granulation quality assurance.

The rapid nucleation and growth dynamics of metal halide perovskite nanocrystals (PNCs) present major challenges in controlling their ensemble evolution and scaling using typical batch syntheses. Continuous flow approaches are an alternative scalable and high-throughput process that can address these limitations by enabling rapid mixing and more precise control of reaction profiles. In this work, we use an acoustically actuated mixer within a continuous microfluidic (MF) platform to study the effect of precursor mixing rate on the synthesis of CsPbBr3 PNCs using the ligand assisted reprecipitation (LARP) approach. It is found that near complete mixing can be achieved at

Recent developments in hybrid organic–inorganic lead halide perovskite solar cells (PSCs) have shown that use of a 2-dimensional (2D) perovskite capping layer on a 3D perovskite absorber layer (3D/...

While perovskite solar cells (PSCs) have emerged as promising low-cost solar power generators, most reported high-performance PSCs employ electron transport layers (ETLs, mainly TiO2) treated at hi...

Sequential deposition is one of the most promising approaches toward achieving scalable fabrication of metal halide perovskite thin films. However, this fabrication approach conventionally lends itself to the incomplete conversion of the lead halide, which impacts the stability, performance, and reproducibility of functional devices featuring such thin films. In this work, we have overcome this limitation by using a simple solvent and process engineering approach. We show that through the use of an optimized dimethylformamide and dimethyl sulfoxide solvent mixture in the precursor solution, and through the judicious control of this solution, the substrate, and final annealing temperatures, highly uniform and mesoporous PbI2 thin films can be deposited. The porous structure of these films is found to accelerate the interdiffusion of CH3NH3I (MAI) during the second-step process when carried out at room temperature, enabling their complete conversion into CH3NH3PbI3 perovskite. Detailed investigations using scanning electron microscopy, X-ray diffraction, grazing-incidence wide-angle X-ray scattering, thermogravimetric analysis, UV–vis absorption, photoluminescence, and time-of-flight secondary ion mass spectrometry have been used to provide mechanistic insights into the porous PbI2 film formation and the interdiffusion process. Solar cells based on planar fluorine-doped tin oxide (FTO)/TiO2/CH3NH3PbI3/spiro-OMeTAD/Au device architectures yield optimized device efficiencies of 19%, which is among the highest for this device structure and perovskite absorber material. The applicability of this enhanced sequential deposition method to other perovskite systems has been further validated through the fabrication of efficient FAxMA1–xPbIxBr3–x and CsPbIxBr3–x solar cells.

The spontaneous zwitterionic copolymerization (SZWIP) of 2-oxazolines and acrylic acid affords biocompatible but low molecular weight linear N-acylated poly(amino ester)s (NPAEs). Here, we present a facile one-step approach to prepare functional higher molar mass cross-linked NPAEs using 2,2′-bis(2-oxazoline)s (BOx). In the absence of solvent, insoluble free-standing gels were formed from BOx with different length n-alkyl bridging units, which when butylene-bridged BOx was used possessed an inherent green fluorescence, a behavior not previously observed for 2-oxazoline-based polymeric materials. We propose that this surprising polymerization-induced emission can be classified as nontraditional intrinsic luminescence. Solution phase and oil-in-oil emulsion approaches were investigated as means to prepare solution processable fluorescent NPAEs, with both resulting in water dispersible network polymers. The emulsion-derived system was investigated further, revealing pH-responsive intensity of emission and excellent photostability. Residual vinyl groups were shown to be available for modifications without affecting the intrinsic fluorescence. Finally, these systems were shown to be cytocompatible and to function as fluorescent bioimaging agents for in vitro imaging.

The ligand assisted reprecipitation (LARP) technique is an accessible and facile method that can synthesize metal halide perovskite nanocrystals (PNCs) under ambient conditions. However, low product yields of less than 30% for LARP and its contemporary methods are indicative of highly inefficient reactions. In this work we apply the principles of green chemistry to the LARP technique for synthesizing CsPbBr3 PNCs and help address this issue. Through these efforts, high product yields of ∼70% are achieved using stochiometric Cs : Pb precursor ratios. This is realized by (i) substituting the conventional toluene (TOL) anti-solvent with ethyl acetate (EA) and (ii) replacing the conventionally used unsaturated oleylamine ligand with the shorter saturated octylamine ligand. These changes also result in a 60% molar reduction in total ligand concentration and a 62.5% reduction in solvent waste during purification. The synthesized PNCs are comparable to the TOL-LARP reference in crystal quality, morphology and phase, with their photoluminescence quantum yields being readily enhanced to over 80% through additions of RNH3Br ligands. The spectral versatility of these materials is demonstrated through post-synthetic chloride and iodide halide anion exchange, which readily yields tunable CsPbX3 derivatives across the visible spectrum. Our EA-LARP protocol is further shown to be readily upscaled to ∼0.5 L, while maintaining good nanocrystal properties and a product yield of 60%.

Near-infrared spectroscopy (NIRS) is an excellent process analytical technology (PAT) tool for active pharmaceutical ingredient (API) quantification during fluidized granulation. Therefore, a portable near-infrared spectrometer combined with a new innovative method of extended iterative optimization technique (EIOT) was used to in-line monitor the API content uniformity during fluidized bed granulation. The principal component analysis (PCA) and partial least squares regression (PLSR) were also used to characterize and predict API concentration with changes from 75% to 125% of the label claim to prove the superiority of EIOT. The API content prediction accuracy of the EIOT method was verified through offline High Performance Liquid Chromatography (HPLC) measurement. Also, the spatial distribution of API in granules was visualized by Raman imaging technology. The results showed that the established NIRS method was suitable for the prediction of API content in fluidized bed granulation, which provides a new idea for the determination of API content during granulation.

The extensive use of halomethanes (CH3X, X = F, Cl, Br, I) as refrigerants, propellants, and pesticides has drawn serious concern due to their adverse biological and atmospheric impact. However, there are currently no portable rapid and accurate monitoring systems for their detection. This work introduces an approach for the selective and sensitive detection of halomethanes using photoluminescence spectral shifts in cesium lead halide perovskite nanocrystals. Focusing on iodomethane (CH3I) as a model system, it is shown that cesium lead bromide (CsPbBr3) nanocrystals can undergo rapid (

Next-generation solar cells, such as dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs), are fabricated in a configuration where light absorbers are located between the electron transporting layer (ETL) and the hole transporting layer (HTM). Although the most efficient DSSCs and PSCs have been fabricated using TiO2 as the ETL, TiO2 exhibits inherently low electron mobility with difficulty controlling the energy levels (i.e., conduction and valence bands) as it possesses a single phase of two components. Here, we report the synthesis of Sr-substituted BaSnO3 (BSSO) by a low-temperature solution process as a new alternative to TiO2 for both PSCs and DSSCs. The energy-level tailoring by Sr incorporation into BaSnO3 minimizes the open-circuit voltage (VOC) loss at the interfaces of ETL/perovskite and ETL/electrolyte in the PSCs and DSSCs, thereby leading to an improved VOC from 0.65 to 0.72 V in DSSC and 1.07 to 1.13 V in PSCs. Additionally, the BSSO ETL-based PSC shows improved photostability compared to the TiO2 analog. Our results show that energy-level tuned BSSO can be applied as a universal ETL for improving efficiency in both PSCs and DSSCs.

Herein, we achieved, air-stable low-temperature processed PSC (L-PSC) using alkali-metal modified ZnO ETLs. Using a simple chemical alkali-metal modification method, the surface defects of the ZnO were effectively passivated. As a result, the interfacial decomposition reactions were suppressed, while raising the Fermi energy level and enhancing electron mobility. The improved interfacial charge transfer and internal electric field in the developed L-PSC using K modified ZnO (ZnO-K) exhibited an improved power conversion efficiency (PCE) of 19.90% with negligible hysteresis, while a pristine ZnO based L-PSC exhibited a PCE of 16.10% with significant hysteresis. The ZnO-K based L-PSC also exhibited remarkably higher long-term air-storage stability (91% retention after 800 h) than pristine ZnO based L-PSCs (36% retention after 800 h) due to the suppressed decomposition reactions. The PCE and air stability of our L-PSC with the modified ZnO are among the highest reported for PSCs processed at ≤150 °C.

Currently, the most efficient perovskite solar cells (PSCs) mainly use planar and mesoporous titanium dioxide (TiO2) as an electron-transport layer (ETL). However, because of its intrinsic photocatalytic properties, TiO2 can decompose perovskite absorber and lead to poor stability under solar illumination (ultraviolet light). Herein, a simplified architectural ETL-free PSC with enhanced efficiency and outstanding photostability is produced by the facile deposition of a bathocuproine (BCP) interlayer. Power conversion efficiency of the ETL-free PSC improves from 15.56 to 19.07% after inserting the BCP layer, which is the highest efficiency reported for PSCs involving an ETL-free architecture, versus 19.03% for the n–i–p full device using TiO2 as an ETL. The BCP interlayer has been demonstrated to have several positive effects on the photovoltaic performances of devices, such as “modulation doping” of the perovskite layer, modification of FTO surface work function, and enhancing the charge-transfer efficien...

The fluidized bed granulation and pellets coating technologies are widely used in pharmaceutical industry, because the particles made in a fluidized bed have good flowability, compressibility, and the coating thickness of pellets are homogeneous. With the popularization of process analytical technology (PAT), real-time analysis for critical quality attributes (CQA) was getting more attention. Near-infrared (NIR) spectroscopy, as a PAT tool, could realize the real-time monitoring and control during the granulating and coating processes, which could optimize the manufacturing processes. This article reviewed the application of NIR spectroscopy in CQA (moisture content, particle size and tablet/pellet thickness) monitoring during fluidized bed granulation and coating processes. Through this review, we would like to provide references for realizing automated control and intelligent production in fluidized bed granulation and pellets coating of pharmaceutical industry.

CsPbI

Improving the stability and tuning the optical properties of semiconducting perovskites are vital for their applications in advanced optoelectronic devices. We present a facile synthetic method for hybrid composites of perovskites and metal-organic frameworks (MOFs). A simple two-step solution-based method without organic surfactants was employed to make all-inorganic lead-halide perovskites (CsPbX3; X = Cl, Br, I, or mixed halide compositions) form directly in the pores of MIL-101 MOF. That is, a polar organic solution of lead halide (PbX2) was impregnated into the MOF pores to give PbX2@MIL-101, which was then subjected to a perovskite-formation reaction with cesium halide (CsX) dissolved in methanol. The compositions of the halogen anions in the perovskites can be modulated with various halide precursors, leading to CsPbX3@MIL-101 composites with X3 = Cl3, Cl2Br, Br2Cl, Br3, Br2I, I2Br, and I3 that exhibit gradual variation of band gap energies and tuned emission wavelengths from 417 to 698 nm.

We fabricated green–red (GR) and blue–red (BR) bilayer stacked quantum dots (QDs) using electrospray deposition. Along with steady state and time-resolved photoluminescence (PL), subnanosecond donor PL decay and corresponding acceptor PL rise signals were observed, which are ascribed to the energy transfer between different visible QDs (heterotransfer). The heterotransfer rates were estimated as (0.57 ± 0.01 ns)−1 and (0.65 ± 0.02 ns)−1 for GR and BR systems, respectively, which agree well with theoretical calculations. Owing to their geometrical proximity, mixed QD layers with GR and BR showed qualitatively higher heterotransfer efficiencies of 64% and 81%, compared to stacked QD layers, which have efficiencies of 23% and 64%, respectively.

We synthesized single-crystalline Sn-based oxides for use as electron-transporting layers (ETLs) in perovskite solar cells (PSCs). The control of the Zn-to-Sn cation ratio (Zn/Sn = 0–2) in a fixed concentration of hydrazine solution leads to the formation of various types of Sn-based oxides, i.e., spherical SnO2 and Zn2SnO4 nanoparticles (NPs), SnO2 nanorods, and Zn2SnO4 nanocubes. In particular, a ratio of Zn/Sn = 1 results in nanocomposites of single-crystalline SnO2 nanorods and Zn2SnO4 nanocubes. This is related to the concentration of free hydrazine unreacted with Zn and Sn ions in the reaction solution, because the resulting OH− concentration affects the growth rate of intermediate phases such as ZnSn(OH)6, Zn(OH)42− and Sn(OH)62−. Additionally, we propose plausible pathways for the formation of Sn-based oxides in hydrazine solution. The Sn-based oxides are applied as ETLs and annealed at a low temperature below 150 °C in PSCs. The PSCs fabricated by using the nanocomposite ETLs consisting of single-crystalline SnO2 nanorods and Zn2SnO4 nanocubes exhibit superior device performance to TiO2-based PSCs due to their excellent charge collection ability and optical properties, achieving a power conversion efficiency of ≥17%.

Significant progresses made in the performance of quantum dot (QD) light-emitting diodes have often been associated with basic changes in QD synthesis, particularly with respect to composition and structure. Here we show that the absolute photoluminescence (PL) quantum yield (QY) of QD can reach 88% with a full width of 21 nm at half-maximum (FWHM) when an optimal thickness is chosen for the outer shell of alloyed, graded core/shell QDs. Thicker shell QD-LEDs with a maximum current efficiency of 56.6 cd A−1, an external quantum efficiency of 14.8%, and a brightness of 62 000 cd m−2 are demonstrated. Green emitting QDs of CdSe@ZnS/ZnS with this optimal thickness is also most resistant to photo-stimulated degradation by UV exposure. Only a 7% loss in PL intensity results even after more than 400 hours of exposure to harsh conditions of 85 °C and 85% relative humidity.

Organic–inorganic hybrid perovskite solar cells have emerged as a promising candidate for next generation solar cells. The most extensively used perovskite absorber is methylammonium lead iodide (MAPbI3). Defect types and quantities, particularly for the defects involving A-site cation (MA+), appear to have significant influence on material properties and on the solar cell performance. In this report, by introducing a smaller sized potassium cation (K+) into the lattice structure of MAPbI3, the photovoltaic performance of mixed-cation perovskite solar cells was enhanced. X-ray diffraction data indicate that the K+ mainly occupied the interstitial position in the perovskite crystal lattice. Systematic study has demonstrated that there are several benefits of introducing the proper amount of K+ to MAPbI3. The increased crystallinity, red shifted photoluminescence (PL) spectra and decreased surface potential result in eminent carrier separation properties and thus reduce the charge recombination in solar cell devices. The optimized mixing range has been investigated; when 0 ≤ K+ content of x (x is the ratio of K+ : Pb2+) ≤ 0.2, the modified mixed perovskite solar cell exhibited better photoelectric conversion efficiencies than that of pristine MAPbI3. Particularly, the perovskite solar cell presents balanced injection capacity for both holes and electrons when x = 0.2, and a conversion efficiency of 19.3% is obtained.

Color-conversion films (CCFs) were fabricated with CuInS2/ZnS quantum dot (QD)-embedded polymer nanofibers and applied for white color emission with blue light-emitting diodes (LEDs). Red-orange color emitting CuInS2/ZnS QDs were synthesized and a photoluminescence quantum yield (PL QY) of 75% was achieved by controlling the Cu : In ratio in the QDs as well as the ZnS shell thickness. QD-embedded polystyrene nanofibers were electrospun on conducting aluminium substrates. The QD-embedded nanofiber (QDEN) structure is believed to reduce the aggregation of the QDs compared to that in a thin-film polymer. Time-resolved photoluminescence (TRPL) analysis showed a longer PL lifetime (138 ns) with the QDEN film than with a mould-cast thin film (45 ns). The longer PL lifetime with the QDEN structure is attributed to decreased quenching due to reduced aggregation. For the white lighting device, the QDEN films were applied as CCFs on a light guide plate (4.3 inch) with a GaN blue LED source. The resulting device demonstrated increased efficiency (from 11.5 to 32.3 lm W−1) and color rendering index values (from 71 to 91) compared to commercial white LEDs. These Cd-free QD-embedded nanofiber films are expected to provide efficient and safe solutions for large-area processing of lighting devices.

A great current density–voltage ( J – V ) hysteresis with respect to the scan direction is important issue in perovskite hybrid solar cells because the power conversion efficiency is sometimes incorrect. Here, we demonstrated >17% mesoscopic CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite hybride solar cells without significant J – V hysteresis with respective to the scan direction and rated by using Li-treated mesoscopic TiO 2 electrode. The Li-treated mesoscopic TiO 2 electrode improved charge separation/injection from MAPbI 3 into mesoscopic TiO 2 , charge transport in mesoscopic TiO 2 , and surface traps because the conduction band edge of mesoscopic TiO 2 was lowered by ~0.1 eV, the mobility of charge carriers was increased from ~1.1×10 −6 cm 2 /V s to ~2.5×10 −6 cm 2 /V s, the conductivity of mesoscopic TiO 2 was increased from ~5.6×10 −7 S/cm to ~1.6×10 −6 S/cm, and the trap density was reduced from ~1.2×10 16 cm −3 to ~9.3×10 15 cm −3 through Li-treatment. Therefore, the average power conversion efficiency was significantly enhanced from 14.84% to 17.26% at 1 sun condition by the Li-treatment of mesoscopic TiO 2 .

Scientific Reports 6: Article number: 35994; published online: 27 October 2016; updated: 16 March 2017. Ujwal Thakur was omitted from the author list in the original version of this Article. This has been corrected in the PDF and HTML versions of the Article, as well as the Supplementary Informationfile.

We report on the fabrication of PbS/CH3NH3PbI3 (=MAP) core/shell quantum dot (QD)-sensitized inorganic-organic heterojunction solar cells on top of mesoporous (mp) TiO2 electrodes with hole transporting polymers (P3HT andPSS). The PbS/MAP core/shell QDs were in situ-deposited by a modified successive ionic layer adsorption and reaction (SILAR) process using PbI2 and Na2S solutions with repeated spin-coating and subsequent dipping into CH3NH3I (=MAI) solution in the final stage. The resulting device showed much higher efficiency as compared to PbS QD-sensitized solar cells without a MAP shell layer, reaching an overall efficiency of 3.2% under simulated solar illumination (AM1.5, 100 mW·cm(-2)). From the measurement of the impedance spectroscopy and the time-resolved photoluminescence (PL) decay, the significantly enhanced performance is mainly attributed to both reduced charge recombination and better charge extraction by MAP shell layer. In addition, we demonstrate that the MAP shell effectively prevented the photocorrosion of PbS, resulting in highly improved stability in the cell efficiency with time. Therefore, our approach provides method for developing high performance QD-sensitized solar cells.

CsPbI3 perovskite nanocrystals are a promising optoelectronic material when stabilized in their cubic phase. While ongoing efforts have addressed this structural challenge through a variety of meta-stabilization approaches, the postsynthesis purification of these nanocrystal dispersions has remained a challenge. In this article, we undertake a detailed investigation into the chemical, optical, and structural changes that arise during purification of CsPbI3 nanocrystals. It is found that nanocrystal degradation can only be avoided through the judicious control of additives within each purification cycle. Under optimized additive-to-nanocrystal ratios, multiple purification cycles can be readily achieved, while retaining the quality and phase stability of the CsPbI3. This facile purification protocol ensures the preparation of high purity and high quality CsPbI3 nanocrystal inks that are suitable for better characterization or integration in optoelectronic devices. The approach has been generalized for CsPbX3 (X = Cl-, Br-, and I-).

High photoluminescence (PL) quantum yield (QY), photostability CdSe@ZnS/ZnS core/multishell quantum dots (CM-QDs) were first applied for bioimaging. The solubility, stability and biocompatible of the fluorescence imaging probes were constructed by self-assembly of CM-QDs and pH-responsive methoxy poly(ethylene glycol)-poly(β-amino ester/amidoamine)-dodecylamine (mPEG-PAEA-DDA) multiblock copolymers. The resulting CM-QDs-loaded mPEG-PAEA-DDA micelles (CM-QDs-PEG-PAEA-DDA) exhibited lower cell cytotoxicity and higher fluorescence intensity than the core/shell CdSe@ZnS QDs-encapsulated mPEG-PAEA-DDA micelles (CS-QDs-PEG-PAEA-DDA). Moreover, the in vivo fluorescence imaging ability confirmed that the CM-QDs-PEG-PAEA-DDA can be employed as a pH-triggerable targeting imaging probe for detection of a rat bearing cerebral ischemia disease. Therefore, we believed that the CM-QDs-PEG-PAEA-DDA may be the next generation of fluorescence imaging probes for targeted diagnosis acidic pathological areas, using pH as a stimulus.

High-quality and millimeter-sized perovskite single crystals of CsPbBr

In CH3NH3PbI3-based high efficiency perovskite solar cells (PSCs), tiny amount of PbI2 impurity was often found with the perovskite crystal. However, for two-step solution process-based perovskite films, most of findings have been based on the films having different morphologies between with and without PbI2. This was mainly due to the inferior morphology of pure perovskite film without PbI2, inevitably produced when the remaining PbI2 forced to be converted to perovskite, so advantages of pure perovskite photoactive layer without PbI2 impurity have been overlooked. In this work, we designed a printing-based two-step process, which could not only generate pure perovskite crystal without PbI2, but also provide uniform and full surface coverage perovskite film, of which nanoscale morphology was comparable to that prepared by conventional two-step solution process having residual PbI2. Our results showed that, in two-step solution process-based PSC, pure perovskite had better photon absorption and longer carrier lifetime, leading to superior photocurrent generation with higher power conversion efficiency. Furthermore, this process was further applicable to prepare mixed phase pure perovskite crystal without PbI2 impurity, and we showed that the additional merits such as extended absorption to longer wavelength, increased carrier lifetime and reduced carrier recombination could be secured.

The ethylene glycol and 2-propanol electrooxidation reaction was studied on carbon dispersed ordered intermetallic PtPb nanocatalysts in KOH solution. X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize ordered intermetallic PtPb/C catalysts. The electrochemical behaviors for the ethylene glycol and 2-propanol electrooxidation reaction were measured in a thin film electrode by cyclic voltammetry, Tafel curves and electrochemical impedance spectroscopy. The results showed that in contrast with PtRu/C and Pt/C catalyst, ordered intermetallic PtPb/C had better electroactivity, and kinetic mechanism of PtPb/C is complex. Although the activity of electrocatalysts depends on many factors, such as modification of geometric and electronic structure by Pt–Pb interaction, crystalline size and so on. But the key factor for each electrooxidation reaction was different. For ethylene glycol electrooxidation, the effect of formation and desorption of poisonous species on activity of catalyst was very significant. For 2-propanol electrooxidation, the modification of geometric and electronic structures may be play a decisive role in the enhance activity of electrocatalyst.