FF Values Research Articles

Unveiling the impact of PC61BM concentration on perovskite solar cell performance

A detailed fabrication method is represented for perovskite solar cells, incorporating various materials and processes based on glove box-free sol-gel deposition routes. Key components include NiOx HTL, PC61BM ETL, BCP HBL, and CH3NH3PbI3 perovskite absorber. Results reveal a significant influence of PC61BM concentration on device efficiency, with champion cells exhibiting optimized VOC, JSC, and FF values at a specific concentration. Statistical analysis of 38 devices confirms the reproducibility and consistency of this concentration, yielding a PCE of 18.2 %. This study investigates a gap in the literature by clarifying the impact of PC61BM solution concentration as a sol-gel deposited electron transport layer. By identifying the optimal concentration and its role in improving device efficiency and reproducibility, investigation contributes to advancing the field of fully sol-gel-based perovskite solar cell technology.

Enhanced photodiode performance: Au/boron-dipyrromethene/n-Si/Ag structure unveiling high photosensitivity and efficiency

In this study, the classical boron-dipyrromethene (4,4- difuoro-4-borata-3a-azonia-4a-aza-s-indacene, BODIPY) unit (C1), its halogenated derivative (C2), and disytryl derivative (C3), which are known for their absorption properties in the near-infrared (NIR) region, were synthesized. Chemical and photophysical investigations were carried out to reveal the complex features of the molecules using a range of spectroscopic techniques and their energies were calculated by Density Functional Theory (DFT) with the same basis set. The BODIPY thin films were coated on n-Si substrates using a spin coater to examine the effect of interlayer on photodiode/photovoltaic properties and Au/BODIPY (C1, C2, C3)/n-Si/Ag photodiodes having rectifying behavior were fabricated. The thermionic emission theory (TET) and modified Norde’s functions were utilized to determine the rectification ratio, ideality factor, series resistance, and barrier height values of diodes. The values of barrier height, ideality factor, and rectification ratio at ± 2 V were calculated as 0.81 eV, 1.83 and 2.47x103 for the Au/C1/n-Si/Ag diode, 0.83 eV, 1.63, and 7.06 x103 for the Au/C2/n-Si/Ag diode and 0.84 eV, 1.51 and 2.14x104 for the Au/C3/n-Si/Ag diode in the dark from the TET, respectively. The values of FF (%) and efficiency were calculated as 38 and 1.51 for the Au/C1/n-Si/Ag diode, 47 and 2.03 for the Au/C2/n-Si/Ag diode, and 56 and 3.68 for the Au/C3/n-Si/Ag diode under 100 mW/cm2 illumination, respectively. With remarkable electrical properties, the Au/C3/n-Si/Ag photodiode stood out among the others, performing better in both dark and light conditions. Therefore, the produced diodes based on the BODIPY thin film can be employed as photodiodes/photovoltaics in optoelectronic applications.

Influence of post-thermal treatment on characteristics of polycrystalline hybrid halide perovskite nanoparticles thin film

A three-dimensional organic–inorganic hybrid halide perovskite (CH3NH3PbI2Br) nanoparticle film was synthesized using solution process in one step. Precursors’ stoichiometry was used to prepare methylammonium bromide and lead (II) bromide in dimethyl formamide. The synthesized CH3NH3PbI2Br solution was spin coated on cleaned ITO prepatterned glass substrate at 2000 rpm. In addition, the influence of post-thermal treatment on the deposited nanoparticles films was evaluated by studying the structural, optical and morphological properties using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectrometry, UV–visible spectrophotometry, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average crystallite sizes were calculated to be ~ 8.0, ~ 9.4, ~ 11.3 and ~ 13.1 nm of as-prepared and annealed films at 400, 500 and 600 °C, respectively. Besides, the bandgaps of 2.22 eV, 1.96 eV, 1.89 eV and 1.63 eV were extrapolated for as-prepared and annealed films at 400 °C, 500 °C and 600 °C, respectively. From J–V curves, the Jsc values of 9.4, 10.6, 11.7 and 12.8 mAcm−2, FF values of 56.99%, 57.25%, 58.94% and 59.26% and PCE values of 2.99%, 3.49%, 3.96% and 4.39% were calculated for as-prepared and annealed CH3NH3PbI2Br films at 400 °C, 500 °C and 600 °C, respectively. The percentage enhancement values of 14.32%, 24.49% and 31.89% compared to as-prepared CH3NH3PbI2Br film. Hence, post-thermal treatment of organic–inorganic halide perovskite material improved its photoconversion efficiency without sacrificing its dimensionality.

Experimental Analysis of Effect of Machined Material on Cutting Forces during Drilling.

Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical-statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5.

Numerical interface optimization of lead-free perovskite solar cells (CH3NH3SnI3) for 30% photo-conversion efficiency using SCAPS-1D

In this study lead free methyl ammonium tin iodide MASnI3 perovskite solar cell was studied and optimized using SCAPS-1D simulator. Different potential materials were assessed to determine their suitability as HTLs and ETLs. Results revealed that among the investigated materials the combination of V2O5 as HTL and IGZO as ETL is most suitable for the performance of MASnI3 solar cell. In an attempt to find the most appropriate material for back contact for further enhancement in performance of solar cell, gold has been found to stand out as the best choice among the examined metals. The wavelength range of 400–900 nm of sun light corresponds to highest quantum efficiency which falls off rapidly beyond this range. Increase in defect density of active layer has been found to have detrimental influence on the performance of solar cell. Above the room temperature cell performance has been found to decline and optimized thickness of active layer has been found to be 0.6 µm at 300 K for which the maximum PCE (30.35%) has been observed. The optimized device Glass/ITO/IGZO/MASnI3/V2O5/Au shows Voc, Isc and FF values of 1.08 V, 33.48 mA/cm2 and 81.53% respectively.

Effect of magnetized water on alkali-activated slag mortars incorporating raw and calcined marble powder

This study investigates the impact of magnetized water (MW) on the fresh and hardened properties of alkali-activated slag (AAS) mortars incorporating raw marble powder (RMP) and calcined marble powder (CMP). In the initial stage of the study, control specimens were manufactured to ascertain the optimal parameters for molarity, curing temperature, and curing time. The optimal parameters were determined based on the highest strength results: a molarity of 10, curing time of 24 hours, and curing temperature of 110 ℃. In the second stage of the study, while maintaining these optimal parameters, RMP and CMP were substituted in place of blast furnace slag (BFS) at rates of 10%, 20%, 30%, and 40%. In this study stage, tap water (TW) and MW were employed as the mixing water. A mini-slump test was conducted to assess the fresh state properties of the prepared AAS mortars. Subsequently, ultrasonic pulse velocity (Upv), flexural strength (ff), and compressive strength (fc) tests were carried out to evaluate the hardened state properties of the specimens. Finally, scanning electron microscopy (SEM) analysis was performed to examine microstructural properties. According to the results, the ff and fc values of the mortars produced with CMP substitution using TW showed an increase of up to 20.6% compared to the mortars based on RMP and produced withTW. Additionally, utilizing MW as the mixing water enhanced the workability of AAS mortars. Consequently, incorporating CMP and MW in AAS mortars further improved fresh and hardened state properties compared to RMP and TW.

FABRIKASI SEL SURYA BERBASIS MATERIAL PEROVSKIT MAPbI3 SEBAGAI SUMBER ENERGI TERBARUKAN

The increasing for energy need encourages all parties to develop alternative energy sources with the concept of renewable energy, which utilizes resources that are always available in nature, such as sunlight energy. The device that can convert sunlight into electrical energy is a solar cell. In this research, solar cells were made based on the MAPbI3 perovskite material as an active material which functions as an absorber to absorb photons of sunlight. The solar cell device was fabricated with the FTO/c-TiO2/mp-TiO2/MAPbI3/PTAA/Au device structure using the OSPD-FDC (one step precursor deposition-fast deposition crystallization) method. The UV-Vis characterization results show that the absorption area of MAPbI3 starts from the wavelength range of 325 nm to 800 nm and shows the presence of an absorption band edge which is a special characteristic of perovskite materials. Meanwhile, characterization of photovoltaic properties produces a power conversion efficiency value of 13% with Jsc, Voc and FF values of 23 mA/cm2, 1.1 V, and 54% respectively

Acenaphthylene-Based Chromophores for Dye-Sensitized Solar Cells: Synthesis, Spectroscopic Properties, and Theoretical Calculations.

A set of acenaphthylene dyes with arylethynyl π-bridges was tested for dye-sensitized solar cells (DSSCs). Crucial steps for the extension of the conjugated system from the acenaphylene core involved Sonogashira coupling reactions. Phenyl, thiophene, benzotriazole, and thieno-[3,2-b]thiophene moieties were employed to extend the conjugation of the π-bridges. The systems were characterized by cyclic voltammetry and by UV-vis absorption and emission. The spectroscopic characterization showed that the last three bridges resulted in red-shifted absorption and emission spectra relative to the parent phenyl-bridged compound, in accordance with TD-DFT calculations. The phenylethynyl derivative 6a achieved a conversion efficiency of 2.51% with Voc, Jsc, and FF values of 0.365 V, 13.32 mA/cm2, and 0.52, respectively. The efficiency of this compound improved to 3.15% with the addition of CDCA (10 mM), representing the best efficiency result in this study. The overall conversion efficiency of the other aryl derivatives 6b-d proved to be significantly inferior (14-40%) to that of 6a due to a significant decrease of Jsc.

Nitrogen doped single layer graphene for CZTS-based thin film solar cells

CdS thin films are commonly utilized as a buffer layer in chalcopyrite thin-film solar cells. However, due to the toxic nature of Cadmium (Cd), ongoing efforts are being directed towards exploring alternative options. In this contribution, doped graphene film with remarkable optical and electrical properties has been introduced for the first time as an alternative buffer layer, replacing CdS in CZTS thin-film solar cell application. In this study, nitrogen-doped graphene (N-doped graphene) film was utilized as a substitute buffer layer in the CZTS thin-film solar cell structure, replacing the conventional CdS thin film. For comparative analysis, CZTS/N-doped graphene and CZTS/CdS traditional solar cell structures were fabricated and separately characterized. The CZTS thin films produced were examined through EDX, XRD, SEM, Raman, optical transmission and PL spectroscopy measurements. According to performed analyses, the Cu-poor and Zn-rich kesterite CZTS thin films exhibited a uniform and dense polycrystalline microstructure as observed in surface and cross-sectional SEM images. XRD spectra of the kesterite CZTS thin film displayed predominant peaks corresponding to the (112), (220/204), and (312/116) diffraction planes of the kesterite CZTS phase. Raman spectra showed a dominant peak at ∼336 cm−1 associated with the kesterite CZTS phase. PL emission spectra indicated transitions from the conduction band to defect levels. The CVD-grown doped graphene film exhibited a 3.43 I2D/IG ratio and a 25 cm−1 FWHM of the 2D peak, indicating a single-layer graphene according to Raman analysis. Permanent nitrogen doping with a 2% atomic concentration was confirmed by XPS measurement. The optical transmission measurement of the single layer doped graphene film showed a 95% transmittance value. Nitrogen doping was contributed to decrease the sheet resistance of the graphene film. The Glass/Mo/CZTS/N-doped graphene/i-ZnO/ITO/Al solar cell displayed a VOC of 0.267 V, JSC of 24.6 mA/cm2, FF of 36.46, and η of 2.37%, showing higher FF and Jsc values but lower conversion efficiency compared to the Glass/Mo/CZTS/CdS/i-ZnO/ITO/Al traditional solar cell structure. Hence, the superior working function and transparency properties position the N-doped graphene film as a competitive buffer layer for use in CZTS-based thin-film solar cells.

Morphological complexity and azimuthal disorder of evolving pore space in low-maturity oil shale during in-situ thermal upgrading and impacts on permeability

In-situ thermal upgrading is used to tune the pore system in low-maturity oil shales. We introduce fractal dimension (D), form factor (ff) and stochastic entropy (H) to quantify the heating-induced evolution of pore morphological complexity and azimuthal disorder and develop a model to estimate the impact on seepage capacity via permeability. Experiments are conducted under recreated in-situ temperatures and consider anisotropic properties—both parallel and perpendicular to bedding. Results indicate that azimuthal distribution of pores in the bedding-parallel direction are dispersed, while those in the bedding-perpendicular direction are concentrated. D values indicate that higher temperatures reduce the uniformity of the pore size distribution (PSD) in the bedding-parallel direction but narrow the PSD in the bedding-perpendicular direction. The greater ff (> 0.7) values in the bedding-parallel direction account for a large proportion, while the dominated in the bedding-perpendicular direction locates within 0.2–0.7, for all temperatures. The H value of the bedding-parallel sample remains stable at ∼0.925 during heating, but gradually increases from 0.808 at 25 °C to 0.879 at 500 °C for the bedding-perpendicular sample. Congruent with a mechanistic model, the permeability at 500 °C is elevated ∼1.83 times (bedding-parallel) and ∼6.08 times (bedding-perpendicular) relative to that at 25 °C—confirming the effectiveness of thermal treatment in potentially enhancing production from low-maturity oil shales.

Spatial distributions, behaviors, and sources of PCDD/Fs in surface water and sediment from the Yangtze River Delta

The Yangtze River Delta (YRD), one of the most economically developed and industrialized regions in China, is confronted with challenges arising from rapid urbanization, particularly environmental pollution. The collection of surface water and sediment samples from forty-nine sites in the YRD was conducted to analyze 2378-substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) congeners. The detected concentrations of PCDD/Fs were 0–5.3 pg TEQ/L in water and 0.12–1493 pg TEQ/g dw in sediment. The PCDD/Fs contamination in the sediment was widespread in the YRD. There were variations in the congener characteristics of PCDD/Fs in surface water and sediment. The proportion of OCDD was significantly lower in surface water samples compared to sediment, while the less chlorine-substituted homologs were found in larger proportions. To understand the partitioning and behavior of dioxins within the water-sediment system, we calculated the organic carbon normalized partition coefficients and fugacity fraction (ff) of PCDD/F congeners. The results revealed that the PCDD/Fs had not attained a state of distributional equilibrium, and the non-specific hydrophobic effect seemed minimally influential on their partitioning between sediment and water. The average ff values, which varied between 0.06 and 0.63, indicated differing migration directions for the PCDD/F congeners. Source identification analysis provided evidence that the dioxins in the river water were primarily attributed to industrial thermal processes. Iron and steel smelting, along with pesticide production and use, were likely responsible for the sediment contamination. This comprehensive analysis underscores the complex nature of PCDD/Fs pollution in the YRD and highlights the necessity for targeted environmental management strategies.

Photovoltaic limitations of FAPbI3 nanocrystal solar cells associated with ligand washing processes

The processing of perovskite nanocrystals (PNCs) solar cells (SCs) usually incorporates ligand washing (LW) procedures. We show that a LW step of FAI in EtAc assists in the removal of the oleic acid/oleylamine ligands and improves the JSC and FF values of FAPbI3 based SCs. Although by increasing the exposure time of EtAc the removal of oleic acid/oleylamine ligands is more effective, sintering/necking of the FAPbI3 results to NC agglomerations and formation of defects/traps are observed within the active layer by the reported photoluminescence studies. Despite identifying the balanced in LW procedure exposure time, limitations on the performance of FAPbI3 PNCs SCs are reported. To identify the photovoltaic limitations impedance spectroscopy studies are presented and show that in the case of FAPbI3 PNC SCs an intermediate frequency response manifests. The observed impedance spectroscopy intermediate frequency response correlates with a parasitic resistance effect, indicating charge transport limitations and charge recombination losses even after the applied LW processing procedure.

Numerical investigation of Aloe Vera-mediated green synthesized CuAlO2 as HTL in Pb-free perovskite solar cells

This study explores green-synthesized delafossite CuAlO2 as a hole transport layer (HTL) in a CH3NH3SnI3-based perovskite solar cells (PSCs) with an FTO/CuAlO2/CH3NH3SnI3/WO3/Au structure. The performances of the cell have been theoretically investigated using SCAPS-1D. Interface defects significantly impact cell efficiency, as defect density increases from 1014 cm−3 to 1020 cm−3 efficiency reducing from 25.3% to 24.45% in the HTL/perovskite junction and from 25.2% to 17.8% in the perovskite/electron transport layer (ETL) interface. PCBM as buffer layer at perovskite/ETL interface compensates for power conversion efficiency (PCE) losses. Optimizing parameters reveals the delafossite CuAlO2-based, lead-free perovskite solar cell achieving peak efficiency at 26.74%, with VOC, JSC, and FF values of 0.99 V, 33.43 mA cm−2, and 81.05%, respectively. This research underscores delafossite CuAlO2 as a promising HTL for eco-friendly, stable CH3NH3SnI3-based perovskite solar cells, emphasizing its potential in enhancing device performance.

Comparative study on perovskite solar cells using P_ZnO, Al_ZnO and In_ZnO as ETMs by SCAPS-1D

This study uses the SCAPS 1D software to analyze solar cells with lead iodide perovskite (CH3NH3PbI3) as the active material and three different types of ZnO doping: undoped (P_ZnO), aluminum-doped (Al_ZnO), and indium-doped (In_ZnO) as the electron transport layer (ETL). This study aims to investigate the effects of charge carrier density on the J-V characteristics and electrical properties (Jsc, Voc, FF, Eff) of a solar cell structure made up of FTO/ETL/CH3NH3PbI3/CuInSe2/Au. Gold makes up the back contact, and tin oxide doped with fluorine (FTO) makes up the front contact. These two compounds have work roles are 5.47 eV and 4.4 eV respectively. Zinc oxide, both undoped and doped, makes up the electron transport layer, whereas methyl ammonium lead iodide makes up the absorber layer. Thin sheets, indium diselenide, and copper make up the hole transport layer. An optimal perovskite layer was obtained by decreasing the electron transportation layer's thickness (ETL) from 500 to 100 nm. For the In_ZnO ETL, this optimization was accomplished at 300K working temperature. Reduced ETL thickness was shown to result in higher efficiency (above 27%), as well as higher fill factor (above 87%). With a Voc value of 1.180V, a FF value of 87.55%, and a Jsc value of 26.276mA/cm2, the greatest efficiency performance of 27.15% was found. Using an absorber layer made of CH3NH3PbI3 with a thickness of 800 nm and indium-doped oxide of zinc (In_ZnO) is the layer that transports electrons, this performance was achieved. The results are obtained at a constant irradiance level of 1000 W/m2, under the AM1.5G spectrum.

Optimal TiO2 Nanoparticles Electron Transporting Layer for Highly Efficient Ambient-atmosphere Fabricated Carbon-based Perovskite Solar Cells

T he electron transporting layer (ETL) is a critical component for carbon-based planar Cs0.17FA0.83Pb(I0.83Br0.17)3 perovskite solar cells (C-PSCs), as it facilitates efficient charge transport between the perovskite material and the cathode. The low temperature processed TiO2 nanoparticles (TiO2 NPs) ETL (150°C) are widely employed in C-PSCs. However, the dispersion of commercial TiO2 NPs in colloid solution is often unstable, leading to particle agglomeration and sedimentation, which negatively affects the performance of C-PSCs. Therefore, it is crucial to achieve stable dispersion of TiO2 NPs in colloid solution before their application as ETL in C-PSCs. Furthermore, the surface properties of the TiO2 ETL such as the uniformity of film significantly impact the overall performance of C-PSCs. The objective of this study was to optimize the TiO2 ETL by investigating the dispersion of TiO2 NPs and varying their concentration in the solution for applying in ambient-atmosphere fabricated C-PSCs. The TiO2 NPs were dispersed in different solvents, including isopropanol, ethanol, and water. As a result, ethanol was the most effective solvent for dispersing TiO2 NPs, demonstrating the best dispersion stability. The concentration of TiO2 NPs in ethanol was then varied between 10-70 mg/ml. The results showed that the optimal concentration was 50 mg/ml, as it produced a high-quality ETL with a more uniform TiO2 film. This optimized TiO2 ETL in C-PSCs resulted in the highest power conversion efficiency (PCE) of 13.10% with FF, VOC, and JSC values of 65.50%, 1.02 V, and 19.52 mA/cm2, respectively.

Machine Learning‐Assisted Fabrication of PCBM‐Perovskite Solar Cells with Nanopatterned TiO2 Layer

To unlock the full potential of PSCs, machine learning (ML) was implemented in this research to predict the optimal combination of mesoporous‐titanium dioxide (mp‐TiO2) and weight percentage (wt%) of phenyl‐C61‐butyric acid methyl ester (PCBM), along with the current density (Jsc), open‐circuit voltage (Voc), fill factor (ff), and energy conversion efficiency (ECE). Then, the combination that yielded the highest predicted ECE was selected as a reference to fabricate PCBM‐PSCs with nanopatterned TiO2 layer. Subsequently, the PCBM‐PSCs with nanopatterned TiO2 layers were fabricated and characterized to further understand the effects of nanopatterning depth and wt% of PCBM on PSCs. Experimentally, the highest ECE of 17.338% is achieved at 127 nm nanopatterning depth and 0.10 wt% of PCBM, where the Jsc, Voc, and ff are 22.877 mA cm−2, 0.963 V, and 0.787, respectively. The measured Jsc, Voc, ff, and ECE values show consistencies with the ML prediction. Hence, these findings not only revealed the potential of ML to be used as a preliminary investigation to navigate the research of PSCs but also highlighted that nanopatterning depth has a significant impact on Jsc, and the incorporation of PCBM on perovskite layer influenced the Voc and ff, which further boosted the performance of PSCs.

Metaheuristic based single and multiobjective optimization of thermoelectric generator

Analytical optimization methods are not applicable for some complex practical problems that lead to explore the numerical/metaheuristic optimization methods. Thermoelectric devices are also complex systems and need metaheuristic methods for their performance optimization. This paper analyses various metaheuristic techniques for performance optimization of thermoelectric generator (TEG). Single and multiobjective optimizations of TEG have been performed to optimize its power output and efficiency. The hot and cold side temperatures, load resistance, length of semiconductor legs, and fill factor of the TEG are used as performance parameters. Single-objective optimization is performed using 13-metaheuristic algorithms and their results are compared in terms of solution optimality and computational time acceptability. It has been observed that the cuckoo search (CS) algorithm is the most suitable in terms of accuracy and speed. CS produced the optimum power output and efficiency of 19.20837 W and 2.4427 % respectively in minimum time. The multiobjective optimization is also performed for simultaneous optimization of the power output and efficiency. Shannon entropy approach is found to be the best technique to determine optimal point on the Pareto front for multiobjective optimization. The optimal values of decision variables, Th Tc, RL, L and FF for multiobjective optimization are found to be 321.195 K, 281.195 K, 0.14250 Ω, 0.5 mm and 0.9 respectively and it produced optimum power output and efficiency of 19.20837 W and 2.25932 % respectively. The statistical and box plot analysis have also been carried out for all the algorithms. The determination of the most suitable algorithm for the faster performance optimization of the TEG, hereby provides the pathways to ascertain the most accurate solution for the power output and efficiency obtainable from the TEG system and hence, delivering the ability to decide the right parameters for the construction of the TEG system with the best performance.

A-A Strategy Enables Desirable Performance of All-Polymer Solar Cells Fabricated with Nonhalogenated Solvents.

Most polymer acceptors have been designed by applying a D (electron-rich unit)-A (electron-deficient unit) strategy, which are principally processed with halogenated solvents to fabricate all-polymer solar cells (all-PSCs). Two novel polymer acceptors, containing an A-A type backbone, were designed and synthesized, which can be readily dissolved in o-xylene. The polymer PY-FBTA, comprising a Y6 derivative as the first A unit and a benzotriazole derivative as the second A unit, shows smaller dihedral angles in the backbone, stronger molecular interactions, higher LUMO level, more complementary absorption spectrum, and better morphology with PM6 than the polymer PY-DPP comprising a diketopyrrolopyrrole derivative as the second A unit. Accordingly, the PM6:PY-FBTA all-PSC achieves a higher PCE of 13.95% than the all-PSC based on PM6:PY-DPP (9.51%) for thoroughly improved Jsc (22.34 mA cm-2), Voc (0.963 V), and FF (64.84%) values, which are fabricated with o-xylene as the solvent. This work demonstrates that the A-A structure is a desirable strategy for designing polymer acceptors for efficient all-PSCs prepared with nonhalogenated solvents.

Effect of fuel-feeding excitation on the isothermal turbulent swirling flow structure in a lean gas turbine model combustor

Fuel-feeding excitation (ff) is an important factor in lean combustors because it controls the combustion process and maintains a stable mixing process. In this work, the structure of turbulent swirling flow is analyzed via large eddy simulation (LES) for a lean partially premixed gas turbine model combustor. The fuel injection is artificially excited at various frequencies of 0 Hz, 15 Hz, 50 Hz, 100 Hz, and 200 Hz. The LES findings show that all fuel-feeding excitation cases have a bubble vortex breakdown as the predominant flow topology. The size of the corner recirculation zone (CRZ) is constant at ff values of 50 Hz, 100 Hz, and 200 Hz, stabilizing the swirling flow in the upstream direction. The fuel-feeding excitation increases the swirl intensity by a rate of 35% and the instantaneous counterrotating vortices spiral further, creating a modulation for the shear layers that increases the rolling-up of small vortices. A mushroom-shaped vortex is formed near the fuel jet, where its position is fixed when ff = 0 Hz and oscillates periodically toward the downstream direction when fuel-feeding excitation is applied. The mushroom-shaped vortex shrinks to a balloon-shaped vortex and merges with the fuel jet when ff = 200 Hz. For all fuel-feeding excitation cases, the precessing vortex core (PVC) considerably increases the velocity fluctuations in the axial directions by 20%. The fuel feeding excitation improves the production of turbulence near the shear layers and the fuel jet exit by rates of 30% and 20%, respectively. In addition, the fuel-feeding excitation enhances the vorticity generation by small structures with a characteristic size that highly depends on the PVC. According to the proper orthogonal decomposition (POD), the first mode has the most energy compared to the other modes due to the prevalence of the PVC and Kelvin-Helmholtz instability in the shear layer region.

Quantitative analysis of vertebral fat fraction and R2* in osteoporosis using IDEAL-IQ sequence

ObjectiveTo investigate the correlation between FF, R2* value of IDEAL-IQ sequence and bone mineral density, and to explore their application value in the osteoporosis.MethodsWe recruited 105 women and 69 men aged over 30 years who voluntarily underwent DXA and MRI examination of lumbar spine at the same day. Participants were divided into normal, osteopenia and osteoporosis group based on T-score and BMD value of DXA examination. One-way ANOVA was adopted to compare the quantitative parameters among the three groups. Independent samples t-test was utilized to compare FF and R2* value between men and women.Pearson correlation analysis was used to research the correlation between FF, R2* value and BMD.ResultsAge, height, weight, BMD and FF value were significantly different among three groups (p < 0.05). No significant difference was found in FF value between male and female group, while R2* value were significantly different. Vertebral FF was moderately negatively correlated with aBMD, especially in women (r = -0.638, p < 0.001). R2* was mildly to moderately positively correlated with aBMD in men (r = 0.350, p = 0.003), but not in women. Moreover, FF was positively correlated with age, R2* was negatively correlated with age in men, and BMD was negatively correlated with age.ConclusionsThe vertebral FF value of IDEAL-IQ sequence has the potential to be a new biological marker for the assessment of osteoporosis. Vertebral FF is moderately negatively correlated with aBMD, especially in women, allowing accuratly quantify the bone marrow fat. R2* value is mildly to moderately correlated with BMD in men and can be served as a complementary tool in the assessment of osteoporosis.