Acid Methyl Ester Research Articles

β-carbolines that enhance GABAA receptor response expressed in oligodendrocytes promote remyelination in an in vivo rat model of focal demyelination.

Demyelination is typically followed by a remyelination process through mature oligodendrocytes (OLs) differentiated from precursor cells (OPCs) recruited into the lesioned areas, however, this event usually results in uncompleted myelination. Potentiation of the remyelination process is an important target for designing effective therapeutic strategies against white matter loss. Here, it was evaluated the remyelinating effect of different β-carbolines that present differential allosteric modulation on the GABAA receptor expressed in OLs. For this, we used a focalized demyelination model in the inferior cerebellar peduncle (i.c.p.) of rats (DRICP model), in which, demyelination by ethidium bromide (0.05%) stereotaxic injection was confirmed histologically by staining with Black-Gold II (BGII) and toluidine blue. In addition, a longitudinal analysis with diffusion-weighted magnetic resonance imaging (dMRI) was made by computing fractional anisotropy (FA), apparent diffusion coefficient (ADC) and diffusivity parameters to infer i.c.p. microstructural changes. First, dMRI analysis revealed FA decreases together with ADC and radial diffusivity (RD) increases after demyelination, which correlates with histological BGII observations. Then, we evaluated the effect produced by three allosteric GABAA receptor modulators, the N-butyl-β-carboline-3-carboxylate (β-CCB), ethyl 9H-pyrido [3,4-b]indole-3-carboxylate (β-CCE), and 4-ethyl-6,7-dimethoxy-9H-pyrido [3,4-b]indole-3-carboxylic acid methyl ester (DMCM). The results indicated that daily systemic β-CCB (1 mg/Kg) or β-CCE (1 mg/Kg) administration for 2 weeks, but not DMCM (0.35 mg/Kg), in lesioned animals increased FA and decreased ADC or RD, suggesting myelination improvement. This was supported by BGII staining analysis that showed a recovery of myelin content. Also, it was quantified by immunohistochemistry both NG2+ and CC1+ cellular population in the different experimental sceneries. Data indicated that either β-CCB or β-CCE, but not DMCM, produced an increase in the population of CC1+ cells in the lesioned area. Finally, it was also calculated the g-ratio of myelinated axons and observed a similar value in those lesioned animals treated with β-CCB or β-CCE compared to controls. Thus, using the DRICP model, it was observed that either β-CCB or β-CCE, positive modulators of the GABAA receptor in OLs, had a potent promyelinating effect.

Contribution of mono- and co-culture of Pseudomonas paralactis, Acinetobacter MN21 and Stenotrophomonas maltophilia to the spoilage of chill-stored lamb

Exploring the contribution of common microorganisms to spoilage is of great significance in inhibiting spoilage in lamb. This work investigated the extent of protein degradation and profile changes of free amino acids (FAAs), free fatty acids (FFAs) and volatile organic compounds (VOCs) in lamb caused by single- and co-culture of the common aerobic spoilage bacteria, P. paralactis, Ac. MN21 and S. maltophilia. Meanwhile, some key VOCs produced by the three bacteria during lamb spoilage were also screened by orthogonal partial least square discriminant analysis and difference value in VOCs content between inoculated groups and sterile group. Lamb inoculated with P. paralactis had the higher total viable counts, pH, total volatile base nitrogen and TCA-soluble peptides than those with the other two bacteria. Some FAAs and FFAs could be uniquely degraded by P. paralactis but not Ac. MN21 and S. maltophilia, such as Arg, Glu, C15:0, C18:0 and C18:1n9t. Co-culture of the three bacteria significantly promoted the overall spoilage, including bacterial growth, proteolysis and lipolysis. Key VOCs produced by P. paralactis were 2, 3-octanedione, those by Ac. MN21 were 1-octanol, octanal, hexanoic acid, 1-pentanol and hexanoic acid methyl ester, and that by S. maltophilia were hexanoic acid. The production of extensive key-VOCs was significantly and negatively correlated with C20:0, C23:0 and C18:ln9t degradation. This study can provide a basis for inhibiting common spoilage bacteria and promoting high-quality processing of fresh lamb.

Deciphering Bisphenol A degradation by Coelastrella sp. M60: unravelling metabolic insights through metabolomics analysis

Microalgae, owing to their efficacy and eco-friendliness, have emerged as a promising solution for mitigating the toxicity of Bisphenol A (BPA), a hazardous environmental pollutant. This current study was focused on the degradation of BPA by Coelastrella sp. M60 at various concentrations (10-50 mg/L). Further, the metabolic profiling of Coelastrella sp. M60 was performed using GC-MS analysis, and the results were revealed that BPA exposure modulated the metabolites profile with the presence of intermediates of BPA. In addition, highest lipid (43%) and pigment content (40%) at 20 and 10 mg/L of BPA respectively exposed to Coelastrella sp. M60 was achieved and enhanced fatty acid methyl esters recovery was facilitated by Cuprous oxide nanoparticles synthesised using Spatoglossum asperum. Thus, this study persuades thepotential of Coelastrella sp. M60 for BPA degradation and suggesting new avenues to remove the emerging contaminants in polluted water bodies and targeted metabolite expression in microalgae.

Sulfonated reduced graphene oxide catalyzed fatty acid methyl ester production from macroalgae Dictyota dichotoma in supercritical conditions

Despite proposed alternative fuels in the recent past, the race for a natural substitute still exists. In this research work, we suggest biodiesel preparation from the rarely explored macroalgae D. dichotoma using a supercritical fluid system of ethanol/ THF. Reduced graphene oxide was prepared using dried jasmine powder as bio-reductant. Reduced graphene oxide was sulphonated using sulfanilic acid, and the catalysts were characterized by XRD, BET surface area, FTIR, and SEM techniques. The reaction conditions for algal oil conversion into biodiesel in supercritical ethanolysis were optimized. FTIR, and GCMS were eployed as analytical tools to analyze the produced biodiesel. The optimized reaction conditions were 265 °C, ethanol: algal oil= 15:1, Reaction time = 10 min, catalyst loading = 5% GO, and THF: ethanol −0.4 for 78% FAEE yield using GO. 10 wt% S-rGO yielded a maximum of 89% FAEE; and 22.55% C18:2. The catalyst was efficient till five cycles. The work assures the utility of abundant macroalgae for alternative fuel production.

Bimetallic PdNi catalyst on cattail Leaves-Derived nanoporous carbon support for synthesis of partially hydrogenated fatty acid methyl ester (H-FAME)

Cattail leaves (CL) have been used as a carbon source to synthesize nanoporous carbon (NPC) support with high surface area (SBET = 2002.12 m2g−1) via hydrothermal carbonization and potassium hydroxide (KOH) activation. The studied catalysts, including monometallic Pd/NPC and Ni/NPC, and bimetallic PdNi/NPC, were synthesized and characterized by using several techniques (e.g., scanning electron microscopy, transmission electron microscopy, nitrogen sorption, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction). Their catalytic activity toward partial hydrogenation of palm biodiesel to H-FAME was tested, and the liquid product composition, cloud point, and oxidation stability were determined. The studied catalysts have a high porosity with the SBET of approximately 2037.34–2187.96 m2g−1 led to excellent metal dispersion. Although Ni did not show high catalytic activity compared to Pd, Ni incorporated with Pd as PdNi/NPC catalyst significantly increased the cis-C18:1 selectivity and prevented the catalytic deactivation during the partial hydrogenation. The oxidation stability of palm biodiesel feedstock was increased from 13.69 to 17.12 h while the cloud points adversely increased by only 3 degrees from 12 to 15 °C (still lower than 16 °C of the Thai industrial recommendation) with bimetallic PdNi/NPC catalyst. The main benefit of bimetallic PdNi/NPC over monometallic Pd/NPC and Ni/NPC is shown through not only higher C18:2 conversion but also much higher cis-to-trans ratio of C18:1 resulting in higher oxidation stability with acceptable compromise on the cloud point increasing. Consequently, the produced palm H-FAME can be used at a high blend ratio.

Improving photovoltaic characteristics of CdS-based hybrid solar cells through Mn incorporation

CdS thin films, both with and without Mn-doping, were grown via chemical bath deposition on indium tin oxide-coated glass substrates for application in hybrid solar cells. X-ray diffraction analysis revealed that Mn doping led to a deterioration in the crystal quality of CdS samples, evidenced by increased microstrain and dislocation density. Mn atoms were interstitially incorporated into the CdS structure, resulting in an expansion of the unit cell volume. Morphological analysis indicated a decrease in grain size from 390 nm to 140 nm for 0 % and 2 % Mn-doped CdS samples, respectively, while maintaining the spherical shape of the CdS thin films. Mn doping also increased the transmittance of CdS thin films, with the highest transparency of 95 % at 580 nm achieved for the 2 % Mn-doped CdS sample. In comparison to undoped CdS (2.38 eV), the band gap of CdS samples initially decreased to 1.84 eV for 1 % Mn doping but significantly increased to 3.03 eV for 2 % Mn-doped CdS. Photoluminescence (PL) data indicated that 2 % Mn-doped CdS thin films exhibited the lowest peak intensity, suggesting that a high concentration of Mn atoms caused non-radiative charge recombination. Additionally, efficient exciton dissociation was observed between CdS:Mn and P3HT:PCBM (poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM)) layers in the 2 % Mn-doped CdS-based device, as per the PL results. Photovoltaic measurements demonstrated that compared to undoped CdS, 2 % Mn doping increased the power conversion efficiency of the CdS-based device from 0.070 % to 0.202 %, indicating an almost threefold increase in hybrid solar cell efficiency. This improvement is likely attributed to the development of a better interface between the CdS:Mn and P3HT:PCBM layers.

Properties of soybean oil oleogels produced from sophorolipid‐derived hydroxy fatty acids, methyl esters and hydrogenated Lesquerella seed oil

AbstractSophorolipids (SL) are glycolipids composed of a sophorose head‐group linked to a hydroxy‐fatty acid tail which makes them a potential source of structurally unique biobased hydroxy fatty acids. Furthermore, Lesquerella is a native southwestern plant that has been commercially cultivated as a replacement for castor seed oil due to high seed oil concentrations of 14‐hydroxy‐eicosenoic acid (14‐OH‐C20:1c11). In this study, SL‐derived hydroxy fatty acids and methyl esters containing 15‐hydroxy‐palmitic acid (15‐OH‐C16), 17‐hydroxy‐stearic acid (17‐OH‐C18), 15‐hydroxy‐palmitic acid methyl ester (15‐OH‐C16ME), 17‐hydroxy‐stearic acid methyl ester (17‐OH‐C18ME), and 13‐hydroxy‐behenic acid methyl ester (13OH‐C22ME) were obtained from the SL produced by two yeast strains. In addition, hydrogenated Lesquerella oil (HLO) was made with ~62% 14‐OH‐eicosanoic (C20) acid (14‐OH‐C20). These materials, along with 12‐hydroxy‐stearic acid (12‐OH‐C18) as a standard for comparison were used to make soybean oil oleogels, and their properties determined. The minimum gelation concentration (MGC) of 12‐OH‐C18 was 1% (wt/wt), while the MGC of 15‐OH‐C16 and 17‐OH‐C18 were 5% and 10%, respectively. The MGC for 15‐OH‐C16ME was 5%, but 17‐OH‐C18ME was unable to form a stable gel at concentrations up to 10%. HLO formed a viscous solution rather than an oleogel, but its crystal morphology underwent a large transformation during storage over a 2.5‐month period, after which it was able to form a stable gel. SL‐based hydroxy fatty acids were able to form oleogels in soybean oil and have the potential to be considered as a new source of low‐molecular weight oleogelators as well as biobased hydroxy fatty acids.

Chemical Constituents from the deep-sea-derived Fungus Aureobasidium melanogenum LUO5.

Three new C10 and C12 aliphatic δ-lactones (1-3), three new fatty acid methyl esters (4-6), and eight known compounds (7-14) were isolated from the marine Aureobasidium sp. LUO5. Their structures were established by detailed analyses of the NMR, HRESIMS, optical rotation, and ECD data. All isolates were tested for their inhibitory effects on nitric oxide production in LPS-induced BV-2 cells. Notably, compound 4 displayed the strongest inhibitory effect with the IC50 value of 120.3 nM.

Magnetic induction heating-assisted synthesis of biodiesel using an alumina/iron oxide nanocatalyst

While generating biodiesel from vegetable oils presents various advantages over fossil fuels, ongoing actions aim to improve the efficiency of this production process. Emphasis is placed on optimizing experimental conditions, including the catalyst selection, reaction media and the energy source for heating and mixing, thereby revealing existing research gaps in biodiesel production. In this sense, we have designed a magnetic nanocatalyst based on iron oxide nanoparticles (IONPs) of 18 nm in diameter incorporated within an alumina matrix of around 500 nm infused with potassium hydroxide that provides the catalyst's mesoporosity and basicity. Magnetization analyses confirmed the superparamagnetic behaviour of the nanocatalyst at room temperature and a saturation magnetisation high enough to ease magnetic recovery for reuse. Additionally, magnetic nanoparticles can serve as nanoheaters when subjected to an alternating magnetic field. The heating efficiency of the isolated IONPs was assessed under various frequency and field conditions, yielding specific absorption rate values of up to 80 W/g. Such heating capacity has allowed the synthesis of fatty acid methyl ester (FAMEs), which constitute the biodiesel at 65 °C under optimal field conditions (100 kHz and 48 kA/m) and ideal reaction parameters: 5 % catalyst, methanol/oil ratio 12:1 and 6 h of reaction, with a conversion of up to 98.6 % determined through NMR characterization of the FAMEs and a 95.6 % yield. FAMEs presence was confirmed by optimizing a swift and efficient FTIR method and their purity by TLC. Overall, the designed nanocatalyst presented for FAME synthesis, which incorporates magnetic separability and effective heating capabilities, holds great promise for cost reduction and process efficiency.

Bulk Heterojunction Solar Cell using Ru Dye Attached PCBM

Ru dye (Z-907) is a crucial photosensitizing material in dye-sensitized solar cells (DSSCs). To enhance the utilization of Ru dye’s photosensitizing properties in bulk heterojunction solar cells, a method was developed to synthesize phenyl-C61- butyric acid methyl ester (PCBM) nanoparticles that are chemically linked to Ru dye. PCBM contains a methoxy (−OCH3) group, whereas Ru dye incorporates a carboxyl group (−COOH) within its molecular structure. By exploiting these complementary functional groups, a successful bond between Ru dye and PCBM was established through an anhydride functional group. The coupling of PCBM with Ru dye results in a modification of the energy levels, yielding lower LUMO (3.8 eV) and HOMO (6.1 eV) levels, compared with the LUMO (3.0 eV) and HOMO (5.2 eV) levels of Ru dye alone. This configuration potentially facilitates efficient electron transfer from Ru dye to PCBM, alongside promoting hole transfer from Ru dye to the conducting polymer. Consequently, the bulk heterojunction solar cells incorporating this Ru dye-PCBM configuration demonstrate superior performance, with an open circuit voltage (Voc) of 0.62 V, short circuit current (Jsc) of 0.63 mA cm−2, fill factor (FF) of 65.6%, and a photovoltaic conversion efficiency (η) of 0.25%.

Bardoxolone methyl prevents metabolic dysfunction-associated steatohepatitis by inhibiting macrophage infiltration.

Bardoxolone methyl (2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid methyl ester, CDDO-Me) is a potent activator of nuclear factor erythroid 2-related factor 2(Nrf2), which induces the expression of antioxidative-associated genes. CDDO-Me exerts protective effects against chronic inflammatory diseases in the kidneys and lungs. However, its pharmacological effects on metabolic dysfunction-associated steatohepatitis (MASH) caused by fat accumulation remain unknown. In this study, we examined the hepatoprotective effects of CDDO-Me in a diet-induced MASH mouse model and elucidated its pharmacological mechanisms using RNA-seq analysis. CDDO-Me was orally administered to mice fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD), and histological, biochemical, and transcriptomic analyses were performed on livers of mice that developed MASH. CDDO-Me administration induced the expression of antioxidant genes and cholesterol transporters downstream of Nrf2 and significantly prevented the symptoms of MASH. Whole-transcriptome analysis revealed that CDDO-Me inhibited the inflammatory pathway that led to phagocyte recruitment, in addition to activating the Nrf2-dependent pathway. Among inflammatory pathways, CC chemokine ligands (CCL)3 and CCL4, which are downstream of NF-κB and are associated with the recruitment of macrophages expressing CC chemokine receptors (CCR)1 and CCR5, were released into the blood in MASH mice. However, CDDO-Me directly inhibited the expression of CCL3-CCR1 and CCL4-CCR5 in macrophages. Overall, we revealed the potent hepatoprotective effect of CDDO-Me in a MASH mouse model and demonstrated that its pharmacological effects were closely associated with a reduction of macrophage infiltration, through CCL3-CCR1 and CCL4-CCR5 inhibition, in addition to Nrf2-mediated hepatoprotective effects.

Versatile Polyoxometalates of Different Structural Dimensionalities for Liquid Phase Catalytic Oxidation

Ionic polymolybdate compounds (IPOM) possessing the anions [Mo8O26]4− and [Mo3O10]2−, and cyclohexylammonium (Cy6N) or anilinium (Anil) as organic cations, namely cyclohexylammonium β-octamolybdate dihydrate (1), cyclohexylammonium trimolybdate hydrate (2), anilinium β-octamolybdate dihydrate (3), anilinium trimolybdate tetrahydrate (4) and anilinium trimolybdate dihydrate (5), were synthesized via simple, eco-friendly one-pot routes. New crystal structures of 1, 2 and 5 were discovered. IPOM compounds with different structural dimensionality, density and ratio of the number of terminal oxo groups/molybdenum atoms (n(oxo)/Mo) were developed. The IPOM compounds promoted the epoxidation of biobased olefins such as the fatty acid methyl esters methyl oleate and methyl linoleate with tert-butylhydroperoxide as oxidant, leading to conversions of at least 81% at 4 h, 70 °C and the corresponding epoxides. The reaction scope of applications for the IPOM catalysts covered cyclooctane oxidation.

Structural elucidation, binding sites exploration and biological activities of bound phenolics from Radix Puerariae Thomsonii

Radix puerariae thomsonii (RPT) contains many phenolics and exhibits various health benefits. Although the free phenolics in RPT have been identified, the composition and content of bound phenolics, which account for approximately 20% of the total phenolic content, remain unknown. In this study, 12 compounds were isolated and identified from RPT-bound phenolic extracts, of which 2 were novel and 6 were reported first in RPT. ORAC and PSC antioxidant activities of 12 compounds, as well as their effects on alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), α-glucosidase, and α-amylase were evaluated. Genistein exhibited the highest ORAC activity, while daidzin demonstrated superior PSC activity. Five compounds, including two new compounds, exhibited the ability to activate both ADH and ALDH. All the compounds except 4-hydroxyphenylacetic acid methyl ester and 2,4,4′-trihydroxydeoxybenzoin demonstrated inhibitory effects on α-glucosidase and α-amylase. Alkaline hydrolysis and stepwise enzymatic hydrolysis revealed that bound phenolics in RPT mainly exist within starch.

Microwave-assisted transesterification of sour cherry kernel oil for biodiesel production: comparison with ultrasonic bath-, ultrasonic probe-, and ohmic-assisted transesterification methods

In this study, sour cherry kernel oil was converted to biodiesel by microwave-assisted transesterification. Evaluations were made of several variables, namely, reaction time (1, 2, 3, 4, and 5 min), microwave power (100, 200, 300, 400, and 500 W), methanol/oil mole ratio (3, 6, 9, 12, and 15), and catalyst (KOH) concentration (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The efficiency of fatty acid methyl esters increased in response to lengthier reaction times, greater microwave power, higher methanol/oil mole ratio, and higher catalyst concentrations up to the optimal level. The optimal reaction conditions for microwave-assisted transesterification were 300 W microwave power, 1.2% catalyst concentration, a methanol/oil mole ratio of 1:2, and a reaction time of 4 min. Microwave-assisted transesterification was more effective than ohmic-, magnetic stirrer-, ultrasonic probe-, and ultrasonic bath-assisted transesterification methods. In conclusion, microwave-assisted transesterification can be suggested as a fast, efficient, and economical method compared to other transesterification methods.

Enhanced Scenedesmus obliquus Cultivation in Plastic-Type Flat Panel Photobioreactor for Biodiesel Production

A plastic-type flat panel photobioreactor (PTFPP) prototype was designed for microalgae cultivation as biodiesel feedstock. The growth, biomass, and lipid production of the oleaginous microalga Scenedesmus obliquus were optimized through the enhanced design and cultivation conditions in the PTFPP. The optimization conditions include cultivation of the microalga in a flat panel photobioreactor manufactured from a 10 µm-thick plastic sheet with dimensions of 40 cm in width and 60 cm in height. The width of the designed plastic bags was adjusted by “4 ports” of circular adhesion points which make the volumetric cultural capacity 5 L. Cultivation of the microalga was optimized through the replacement of the sodium nitrate of the BBM medium with urea as a nitrogen source. Cultivation bags were subjected to continuous illumination with 3000 lux white, fluorescent lamps and aerated with 1.5 L air/min (equal to 0.3 VVM). Biomass production from the designed PTFPP reached 3 g/L with around 40% lipid content (on a dry weight basis). Based on a GC-MS analysis of the produced fatty acid methyl ester (biodiesel) from S. obliquus, the percentage of C16 and C18 fatty acids reached more than 90% of the defined fatty acids. Out of this percentage, 66.6% were unsaturated fatty acids. The produced fatty acid profile of the S. obliquus biomass cultivated in the designed PTFPP prototype could be considered a suitable feedstock for biodiesel production.

Chitosan-based delivery of fish codon-optimised Caenorhabditis elegans FAT-1 and FAT-2 boosts EPA and DHA biosynthesis in Sparus aurata

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential fatty acids required in healthy balanced diets for humans. To induce sustained production of n-3 LC-PUFA in gilthead seabream (Sparus aurata), chitosan-tripolyphosphate (TPP) nanoparticles encapsulating plasmids expressing fish codon-optimised Caenorhabditis elegans FAT-1 and FAT-2 were intraperitoneally administered every 4 weeks (3 doses in total, each of 10 μg plasmid per g of body weight). Growth performance and metabolic effects of chitosan-TPP complexed with pSG5 (empty plasmid), pSG5-FAT-1, pSG5-FAT-2 and pSG5-FAT-1 + pSG5-FAT-2 were assessed 70 days post-treatment. Tissue distribution analysis showed high expression levels of fish codon-optimised FAT-1 and FAT-2 in the liver (> 200-fold). Expression of fat-1 and fat-1 + fat-2 increased weight gain. Fatty acid methyl esters assay revealed that co-expression of fat-1 and fat-2 increased liver production and muscle accumulation of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 LC-PUFA, while decreased the n-6/n-3 ratio. Co-expression of fat-1 and fat-2 downregulated srebf1 and genes encoding rate-limiting enzymes for de novo lipogenesis in the liver, leading to decreased circulating triglycerides and cholesterol. In contrast, FAT-2 and FAT-1 + FAT-2 upregulated hepatic hnf4a, nr1h3 and key enzymes in glycolysis and the pentose phosphate pathway. Our findings demonstrate for the first time efficient and sustained production of EPA and DHA in animals after long-term treatment with chitosan-TPP-DNA nanoparticles expressing FAT-1 and FAT-2, which enabled the production of functional fish rich in n-3 LC-PUFA for human consumption.

Spiro-Bifluorene-Cored Dopant-Free Conjugated Polymeric Hole-Transporting Materials Containing Passivation Parts for Inverted Perovskite Solar Cells.

Two spiro-bifluorene-based dopant-free HTMs (X22 and X23) have been synthesized by facilely condensing spiro-bifluorene diamine with 3,4-ethylenedioxythiophene (EDOT)-5,7-dicarbonyl dichloride and 2,3,5,6-tetrafluoro-terephthaloyl dichloride, respectively. In the X22 molecule, lone pairs of electrons on the sulfur (S) and oxygen (O) functional groups interact with the perovskite materials. The hole mobility (μh) of X22 (3.9 × 10-4 cm2 V-1 S1-) is more than twice that of X23 (1.4 × 10-4 cm2 V-1 S1-). The conductivity (σ0) of X22 is 2.73 × 10-4 S cm-1, which is also higher than that of X23 (2.39 × 10-4 S cm-1). The EDOT moiety benefits the contact angle of CH3NH3PbI3 precursor solutions on HTMs as low as 24°. The X22-based device with an indium-doped tin oxide/hole transport material (HTM)/CH3NH3PbI3/phenyl-C61-butyric acid methyl ester (PC61BM)/bathocuproine/Ag structure achieves a power conversion efficiency (PCE) of 19.18%. The PCE of the device based on X23 containing fluorine is 18.70%, and the contact angle between HTM and the perovskite precursor solution is 32°. The X22- and X23-based devices at ambient temperature (≈25 °C) in N2 retain 86% and 79% of the initial PCE after 150 days. The effect of S, O, and F heteroatoms plays an important role in the side chain modification of HTMs, improving defect passivation in HTM/CH3NH3PbI3 interfaces by multiple functional groups.

Interface passivation using diketopyrrolopyrrole‐oligothiophene copolymer to improve the performance of perovskite solar cells

AbstractThe unprecedented increase in power conversion efficiency (PCE) of low‐cost organo‐inorganic halide perovskite solar cells (OIHPSCs) toward its Shockley‐Queisser limit intriguingly has prompted researchers to investigate the disadvantages of these devices. The issue of operational stability is the main hurdle challenging the way forward for commercialization. To address this, various engineering processes like composition, additives, anti‐solvents, bulk and interface passivation, and deposition techniques have been widely applied to manage both extrinsic and intrinsic factors that induce degradation of the OIHPSCs. In this work, we employed interface passivation, which is an efficient approach to reduce nonradiative recombination. An ultrathin layer of electron donor diketopyrrolopyrrole‐oligothiophene copolymer (DPP860) was applied as an interface passivator between the photoactive layer and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM). The role of the interface passivation on optoelectronic properties of the OIHPSCs was assessed using current density versus voltage (J‐V) characteristics, photoluminescence spectroscopy and time‐resolved photoluminescence spectroscopy. The findings show devices treated with DPP860 exhibit enhanced current density (Jsc) and fill factor, attributing for suppressed nonradiative recombination. Moreover, it shows relative improvement in the stability of the device. The results of this finding reveal that using oligothiophene copolymer can enhance the photovoltaic performance and the stability of inverted OIHPSCs in the ambient environment.

Interface defect formation for atomic layer deposition of SnO2 on metal halide perovskites

With the rapidly advancing perovskite solar cell (PSC) technology, dedicated interface engineering is critical for improving device stability. Atomic layer deposition (ALD) grown metal oxide films have drawn immense attention for the fabrication of stable PSC. Despite the advantages of ALD, the deposition of metal oxides directly on bare perovskite has so far not been achieved without damaging the perovskite layer underneath. In addition, the changes to the physicochemical and electronic properties at the perovskite interface upon exposure to the ALD precursors can alter the material and hence device functionality. Herein, we report on a synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES) investigation of the interface between metal halide perovskite (MHP) absorber and ALD-SnO2 electron transport layer. We find clear evidence for the formation of new chemical species (nitrogen compound, lead dihalides) and an upward band bending in the MHP and downward band bending in the SnO2 towards the MHP/ALD-SnO2 interface. The upward bending at the interface forms an electron barrier layer of ∼400 meV, which is detrimental to the PSC performance. In addition, we assess the effectiveness of introducing a thin interlayer of the organic electron transport material Phenyl-C61-butyric acid methyl ester (PCBM) between MHP and ALD-SnO2 to mitigate the effects of ALD deposition.

Coumarin based glyoxylate photoinitiators for free radical and cationic Photopolymerizations with UV-Visible LED irradiation

High-performance photoinitiators (PIs) play a crucial role in ultraviolet–visible (UV–Vis) photopolymerization. In this study, three coumarin-3-oxoacetic acid methyl esters (COAEs) which demonstrate significant UV–Vis absorption within the 300–500 nm range were synthesized and studied. Real-time fourier transform infrared (RT-FTIR) and photo-differential scanning calorimetry (photo-DSC) experiments demonstrated that these PIs can function as Type I and Type II PIs for initiating free radical polymerization (FRP) of acrylate monomers. Additionally, they can serve as photosensitizers for iodonium salts and sulfonium salts, enabling cationic photopolymerization (CP) of epoxy and oxetane monomers. Remarkably, even at low concentrations of 0.01 wt%, they can effectively initiate the deep curing of Tri-(propylene glycol) diacrylate (TPGDA) to a depth of approximately 9 cm after 5 min of irradiation with a 415 nm or 450 nm LED light source. Furthermore, the COAEs exhibit satisfactory photobleaching properties, making them suitable for colorless applications in photopolymerization. The photochemical and photophysical properties of the COAEs were thoroughly investigated using absorption spectroscopy, electron spin resonance, cyclic voltammetry experiments, and photoinduced decarboxylation experiments to elucidate the photoinitiation mechanism. Cytotoxicity experiments revealed that COAE-N exhibited good cytocompatibility. Therefore, the exceptional polymerization properties of COAEs offer promising prospects for FRP and CP applications. Additionally, their efficient photobleaching characteristics make them highly suitable for deep photopolymerization applications. Moreover, the low cytotoxicity of COAEs suggests significant potential for biomedical applications such as dental restoration.