Wavelength-Tunable and Water-Stable Cesium-Lead-Based All-Bromide Nanocrystal-Polymer Composite Films Using Ultraviolet-Curable Prepolymer as an Anti-Solvent.

All-inorganic metal halide perovskite nanocrystals (IPeNCs) have become one of the most promising luminescent materials for next-generation display and lighting technology owing to their excellent color expression ability. However, research on IPeNCs with stable blue emission is limited. In this paper, we report stable blue emissive all-bromide IPeNCs obtained through a modified ligand-assisted reprecipitation method using an ultraviolet (UV)-curable prepolymer as the anti-solvent at a low temperature. We found that the blue emission originates from quantum-confined CsPbBr3 nanoparticles formed together with the colorless wide-bandgap Cs4PbBr6 nanocrystals. When the temperature of the prepolymer was increased from 0 to 50 °C, CsPbBr3 nanoparticles became larger and more crystalline, thereby altering their emission color from blue to green. The synthesized all-bromide blue-emitting IPeNC solution remained stable for over 1 h. It also remained stable when it was mixed with the green-emitting IPeNC solution. By simply exposing the as-synthesized IPeNC-prepolymer solutions to UV light, we formed water-stable composite films that emitted red, green, blue, and white colors. We believe that this synthetic method can be used to develop color-emitting composite materials that are highly suitable for application as the color conversion films of full-color liquid crystal display backlight systems and lighting applications.

Enhanced Light Absorption by Facile Patterning of Nano-Grating on Mesoporous TiO2 Photoelectrode for Cesium Lead Halide Perovskite Solar Cells.

CsPbIBr2, a cesium-based all-inorganic halide perovskite (CsPe), is a very promising alternative material to mainstream organic-inorganic hybrid halide perovskite (HPe) materials owing to its exceptional moisture stability, thermal stability, and light stability. However, because of the wide band gap (2.05 eV) of CsPbIBr2, it has a low power conversion efficiency (PCE), which hinders its application in highly efficient solar cells. In this study, a facile nanoimprinted one-dimensional grating nanopattern (1D GNP) formation on mesoporous TiO2 (mp-TiO2) photoelectrodes was introduced to improve the effective light utilization and enhance the performance of CsPbIBr2 perovskite solar cells (PSCs). The 1D GNP structure on the mp-TiO2 layer increases the light absorption efficiency by diffracting the unabsorbed light into the active mp-TiO2 and CsPbIBr2 layers as well as increasing the charge separation and collection due to the extended interfacial contact area between the mp-TiO2 and CsPbIBr2 layers. Consequently, both the current density (JSC) and the fill factor (FF) of the fabricated cells improved, leading to over a 20% enhancement in the solar cell's PCE. Thus, this periodic grating structure, fabricated by simple nanoimprinting, could play an important role in the large-scale production of highly efficient and cost-effective Cs-based PSCs.

Efficient TiO2 Surface Treatment Using Cs2CO3 for Solution-Processed Planar-Type Sb2S3 Solar Cells.

We report a highly effective surface treatment method for planar-type Sb2S3 solar cells by employing a Cs2CO3-modified compact TiO2 (c-TiO2) electron transport layer. It is found that surface treatment using a Cs2CO3 solution can shift the work function of c-TiO2 upward and reduce its surface roughness. As a result, compared with the power conversion efficiency of untreated solar cells, that of the treated solar cells with a glass/FTO/c-TiO2(/Cs2CO3)/Sb2S3/P3HT/Au structure significantly improved from 2.83 to 3.97%. This study demonstrates that the introduction of Cs2CO3 on a c-TiO2 layer is a simple and efficient way to adjust the work function of the electron transport layer and fabricate high-performance planar-type Sb2S3 solar cells.

Fabrication of Sb2S3 Hybrid Solar Cells Based on Embedded Photoelectrodes of Ag Nanowires-Au Nanoparticles Composite.

The Ag nanowire (NW) + Au nanoparticle (NP)-embedded TiO2 photoelectrodes were adopted for conventional planar TiO2-based Sb2S3 hybrid solar cells to improve the cell efficiency. Compared to conventional planar TiO2-based Sb2S3 hybrid solar cells, the Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells exhibited an improvement of approximately 40% in the cell efficiency due to the significant increase in both Jsc and Voc. These enhanced Jsc and Voc were attributed to the increased surface area, charge-collection efficiency, and light absorption by embedding the Ag NWs + Au NPs composite. The Ag NW + Au NP/TiO2-based Sb2S3 hybrid solar cells showed the highest efficiency of 2.17%, demonstrating that the Ag NW + Au NP-embedded TiO2 photoelectrode was a suitable photoelectrode structure to improve the power conversion efficiency in the Sb2S3 hybrid solar cells.

Effect of Perovskite Overlayers on TiO2 Electrodes in Perovskite-Sensitized Solar Cells.

In this paper, we have studied the effect of the thickness of a CH3NH3PbI3 perovskite overlayer on mesoporous TiO2 electrodes in perovskite solar cells. The overlayers were prepared by spin coating PbI2 films on the electrodes, which were subsequently exposed to a CH3NH3I/2-propanol solution. We controlled the thickness of the perovskite overlayer by changing the PbI2 solution concentration. The thicknesses of the overlayers spin-coated from 0.5, 0.75, 0.9, and 1 M PbI2 solutions were approximately 179, 262, 316, and 341 nm, respectively. Perovskite solar cells with an approximately 316-nm-thick overlayer showed the highest efficiency of 9.11%. We conclude that optimization of the perovskite overlayer thickness in the solar cell structure is necessary to improve the cell efficiency.

Electrospun ZnO Nanofibers as a Photoelectrode in Dye-Sensitized Solar Cells.

A nanoparticle-based DSSC shows limited efficiency levels due to its disordered geometrical structure and interfacial interference during electron transport, whereas the use of nanofibers in a DSSC can increase the electron mobility at the interfacial area of the materials due to the reduced recombination of electrons before reaching the collecting electrode. In this study, we describe the fabrication and characteristics of a ZnO nanofiber electrode for DSSC. From the results of a thermogravimetric analysis, a stepped heat treatment was developed for the calcinations of the ZnO electrodes. The ZnO electrode morphology and crystalline structure were confirmed by scanning electron microscopy and the X-ray diffraction patterns, respectively. The DSSC with the ZnO nanofiber photoelectrode (wire shaped) created by electrospinning showed an enhanced short-circuit current density (37% enhancement) compared to that of a ZnO sphere particle-shaped photoelectrode under irradiation of AM 1.5 simulated sunlight (100 mW/cm2). Moreover, we have investigated the origin of the improved performance through electrochemical impedance spectroscopic (EIS) and open-circuit voltage-decay (OCVD) measurements.

Fabrication of High Efficiency Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Embedded in Ti Substrate.

We have embedded a TiO2 nanoparticle (NP) photoelectrode in a Ti substrate to improve the cell efficiency of conventional TiO2 NP based dye-sensitized solar cells (DSSCs) using Ti substrate. Compared to the conventional standing-type (TiO2 NPs on Ti substrate) DSSCs, the embedded-type (TiO2 NPs embedded in Ti substrate) DSSCs have shown an approximately 35% improvement in power conversion efficiency due to the improvement of J(sc). The embedded-type DSSCs have more charge transport paths than do standing-type DSSCs due to the increase of contact area between the TiO2 NP sidewall and the Ti substrate. This increased contact area decreases the electrical resistance and increases the charge collection efficiency, which leads to the improvement of J(sc). The embedded-type NP-DSSCs are very effective DSSC structures for enhancing the power conversion efficiency of Ti substrate based DSSCs.

Effect of TiCl4 Post-Treatment on the Embedded-Type TiO2 Nanotubes Dye-Sensitized Solar Cells.

We have studied the effect of TiCl4 post-treatment on the embedded-type TiO2 nanotubes (NT)-dye-sensitized solar cells (DSSCs). The TiO2 nanoparticles layer formed on TiO2 NTs surface by TiCl4 post-treatment showed different morphologies depending on TiCl4 treatment temperature. These different morphologies influenced the cell efficiency of TiO2 NT-DSSCs. The TiO2 NT treated with TiCl4 at 50 °C exhibited a rougher surface than that treated at 70 °C. The rough surface of the TiO2 NT improved the charge exchange between the dye and electrolyte. The TiO2 NT treated with TiCl4 at 50 °C showed better fill factor and cell efficiency than that treated at 70 °C. The TiCl4 post-treatment of TiO2 NT was effective at conditions of low temperature and long times. The TiO2 NT-DSSCs with TiCl4 post-treatment at 50 °C for 1.5 h showed an efficiency of 6.52%.

Effect of anodic aluminum oxide template imprinting on TiO2 blocking layer of flexible dye-sensitized solar cell.

In this paper, we have proposed a new flexible dye-sensitized solar cell (DSSC) structure that employs an Anodic Aluminum Oxide (AAO) template imprinted TiO2 blocking layer, in which the AAO template creates TiO2 nano-particle aggregated islands on the TiO2 blocking layer. The TiO2 blocking layer prevents charge recombination between the metal foil and the liquid electrolyte. TiO2 nano-particle aggregated islands improve the scattering of incident light during back illumination and provide the wider surface area, yielding enhanced power conversion efficiency (PCE). All the flexible DSSC structure with TiO2 nano-particle aggregated islands on the TiO2 blocking layer exhibited higher photocurrent than did conventional DSSC because light that passed through the photoanode was scattered, thereby giving it improved PCE that was as much as 23% higher than that of a conventional DSSC. This proposed method is an effective manufacturing process for flexible DSSC.

Characterization of the transport, metabolism, and pharmacokinetics of the dopamine D3 receptor-selective fluorenyl- and 2-pyridylphenyl amides developed for treatment of psychostimulant abuse.

The recent discovery of novel high-affinity and selective dopamine D3 receptor (DA D3R) antagonists and partial agonists has provided tools with which to further elucidate the role DA D3R plays in substance abuse. The present study was conducted to evaluate the transport, metabolism, pharmacokinetics, and brain uptake of the DA D3R-selective fluorenyl amides, NGB 2904 [N-(4-(4-(2,3-dichlorophenyl)piperazin-1-yl)butyl)-9H-fluorene-2-carboxamide] fumarate) and JJC 4-077 [N-(4-(4-(2,3-dichlorophenyl)piperazin-1-yl)-3-hydroxybutyl)-9H-fluorene-2-carboxamide hydrochloride], and the 2-pyridylphenyl amides, CJB 090 [N-(4-(4-(2,3-dichlorophenyl)piperazin-1-yl)butyl)-4-(pyridine-2-yl)benzamide hydrochloride] and PG 01037 [N-(4-(4-(2,3-dichlorophenyl)piperazin-1-yl)-trans-but-2-enyl)-4-(pyridine-2-yl)benzamide hydrochloride], all of which have been studied in animal models of psychostimulant abuse. Additional screening with a panel of human and rat Supersomes was performed for NGB 2904 and PG 01037. Drug-stimulated ATPase activation assays and bidirectional transport and efflux assays were used to test for substrate specificity of NGB 2904 and PG 01037 for human and rat efflux transporters. All compounds exhibited moderate elimination half-lives, ranging from 1.49 to 3.27 h, and large volumes of distribution (5.95-14.19 l/kg). The brain-to-plasma ratios ranged from 2.93 to 11.81 and were higher than those previously reported for cocaine. Brain exposure levels of NGB 2904 and PG 01037 were significantly reduced after intraperitoneal administration compared with intravenous administration. The metabolism of these compounds was mediated primarily by CYP3A subfamilies. PG 01037 was a P-glycoprotein-transported substrate. Higher doses of these compounds are often required for in vivo action, suggesting decreased bioavailability via extravascular administration that may be attributed to high drug efflux and hepatic metabolism. These studies provide important preclinical information for optimization of next-generation D3R selective agents for the treatment of drug addiction.

Application of a sample pooling method for the accelerated assessment of the rate of uptake of drugs by the brain in rats.

The purpose of this study was to examine the feasibility of applying a sample pooling method to the accelerated estimation of the uptake clearance of drugs to the brain in rats. Brain uptake clearances (CL(uptake)) were estimated for five model compounds using the sample pooling method and an integration plot analysis. CL(uptake) was also evaluated for caffeine and theophylline by brain microdialysis. The parameters and throughput of the pooling method were compared with those of typically used standard methods. The correlation for CL(uptake) was statistically significant (P<0.005) between the integration plot and the current method; the throughput of evaluation was 15-fold higher for the sample pooling method. A comparison of CL(uptake) values indicated that the three methods showed comparable results for caffeine while the CL(uptake) of theophylline using the proposed method was significantly different from those of the other methods. A kinetic analysis indicated that a compound with a slower CL(uptake) and longer half-life (e.g., theophylline) is more prone to error and that the lower limit of the CL(uptake) of 0.17 mL min(-1) (g brain)(-1) may be set so as to have an error less than 20% of the estimation. These results suggest that the sample pooling method is applicable for use in the accelerated estimation of the uptake clearance of compounds in the brain for which the value is greater than 0.17 mL min(-1) (g brain)(-1).

Comparison of pharmacokinetics of loxoprofen and its active metabolites after an intravenous, intramuscular, and oral administration of loxoprofen in rats: evidence for extrahepatic metabolism.

The objective of this study was to characterize the extent of the formation of the active (trans-alcohol form) and inactive (cis-alcohol) metabolites of loxoprofen and to compare the kinetics after its intragastric, intravenous, and intramuscular administrations in rats. After intravenous administration of the drug at doses of 5-20 mg/kg, the clearance and the volume of distribution for loxoprofen, and the ratios of the AUC for the metabolites to the parent drug were not statistically different with the dosage; the formation clearances were 1.08 and 0.87 mL/min/kg for the active and its isomeric metabolite, respectively. After the intragastric, intravenous, or intramuscular administration, AUC for loxoprofen and the metabolites at a dose of 10 mg/kg were not statistically different for the different routes of administration. The formation of the metabolites with the concomitant loss of loxoprofen was found in incubations with liver homogenates and blood but not with a muscle homogenate or plasma, indicating that the conversion of loxoprofen to the metabolites may occur both in the liver and extraheptic tissue(s). Thus, approximately 22% of the loxoprofen may have been converted to the active metabolite in the liver and the extraheptic tissue(s) and the pharmacokinetics of the active metabolite was independent of the route of administration.

Analysis of structure-activity relationships for the 'B-region' of N-(3-acyloxy-2-benzylpropyl)-N(')-[4-(methylsulfonylamino)benzyl]thiourea analogues as vanilloid receptor antagonists: discovery of an N-hydroxythiourea analogue with potent analgesic activity.

The structural modifications on the B-region of the potent and high affinity vanilloid receptor (VR1) lead ligand N-(3-acyloxy-2-benzylpropyl)-N(')-[4-(methylsulfonylamino)benzyl]thiourea were investigated by the replacement of the thiourea with diverse isosteric functional groups. Structure-activity analysis indicated that the A-region in this series was the primary factor in determining the agonistic/antagonistic activities regardless of the B-region. The N(C)-hydroxy thiourea analogues (12, 13) showed excellent analgesic activities in the acetic acid writhing assay compared to the parent thiourea analogues.

Phenolic modification as an approach to improve the pharmacology of the 3-acyloxy-2-benzylpropyl homovanillic amides and thioureas, a promising class of vanilloid receptor agonists and analgesics.

In order to improve the analgesic activity and pharmacokinetics of thioureas 2 and 3, which we previously developed as potent vanilloid receptor (VR) agonists, we prepared and characterized phenolic modifications of them and of their amide surrogates (7, 8). The aminoethyl analogue of the amide template 13 was a potent analgesic with an EC50=0.96 microg/kg in the AA-induced writhing test and with better in vivo stability than the parent phenol.